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DESCRIPTION
DATA PROCESSING DEVICE AND DATA PROCESSING METHOD
Technical Field
[0001] The present technology relates to a data
processing device and a data processing method. In
particular, the present technology relates to a data
processing device and a data processing method that make
it possible to ensure good communication quality in a
data transmission using LDPC codes.
Background Art
[0002] Some of the information to be published in this
specification and drawings, Samsung Electronics Co. to
conduct joint development with Sony Corporation, Ltd.
(hereinafter, referred to as Samsung) is one that has
received the offer from the (explicitly in the drawings).
[0003] LDPC (Low Density Parity Check) code has high
error correction capabilities, and is widely used in
recent years in a transmission system including a digital
broadcasting such as DVB (Digital Video Broadcasting)-
S.2, DVB-T.2, DVB-C.2 in Europe, and ATSC (Advanced
Television Systems Committee)3.0 in the United States
(for example, refer to Non-Patent Document 1).
[0004] Recent studies has revealed that as the code
length of the LDPC code is prolonged, the LDPC code
achieves the performance as close as the Shannon limit
similar to the turbo code or the like. Also, the LDPC
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code has a property that the minimum distance is
proportional to the code length. As the advantageous
features of the LDPC code, the block error probability
characteristic is good, and a so-called error floor
phenomenon that is observed in the decoding
characteristic of the turbo code or the like is less
likely to occur.
[0005] Non-Patent Document 1: DVB-S.2 : ETSI EN 302
307 V1.2.1 (2009-08)
Summary of Invention
Problem to be solved by the Invention
[0006] Data transmission using an LDPC code, for
example, LDPC codes, is a symbol of QPSK (Quadrature
Phase Shift Keying) orthogonal modulation such as
(digital modulation) (is symbolized), the symbol, the
signal points of orthogonal modulation it is mapped to be
transmitted.
[0007] The data transmission using the LDPC code as
described above, it is becoming spread worldwide and is
requested to ensure a satisfactory communication quality.
[0008] The present technology has been made in view of
such circumstances, and, in the data transmission using
the LDPC code, is to ensure good communication quality.
Means for solving the Problem
[0009] The first data processing device/data
processing method of the present technology includes a
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group-wise interleave unit/step of performing group-wise
interleave of interleaving in a 360-bit group unit an
LDPC code whose code length is 64800 bits and code rate
is 10/15, 11/15, 12/15 or 13/15, the (i + 1)th bit group
from the beginning of the LDPC code of the 64800 bits
being as a bit group i, and in the group-wise interleave,
a sequence of bit group 0 to 179 of the 64800 bits of the
LDPC code being interleaved into the following sequence
of the bit group:
178, 140, 44, 100, 107, 89, 169, 166, 36, 52, 33, 160, 14,
165, 109, 35, 74, 136, 99, 97, 28, 59, 7, 29, 164, 119,
41, 55, 17, 115, 138, 93, 96, 24, 31, 179, 120, 91, 98,
43, 6, 56, 148, 68, 45, 103, 5, 4, 10, 58, 1, 76, 112,
124, 110, 66, 0, 85, 64, 163, 75, 105, 117, 87, 159, 146,
34, 57, 145, 143, 101, 53, 123, 48, 79, 13, 134, 71, 135,
81, 125, 30, 131, 139, 46, 12, 157, 23, 127, 61, 82, 84,
32, 22, 94, 170, 167, 126, 176, 51, 102, 171, 18, 104, 73,
152, 72, 25, 83, 80, 149, 142, 77, 137, 177, 19, 20, 173,
153, 54, 69, 49, 11, 156, 133, 162, 63, 122, 106, 42, 174,
88, 62, 78, 86, 116, 155, 129, 3, 9, 47, 50, 144, 114,
154, 121, 161, 92, 37, 38, 39, 108, 95, 70, 113, 141, 15,
147, 151, 111, 2, 118, 158, 60, 132, 168, 150, 21, 16,
175, 27, 90, 128, 130, 67, 172, 65, 26, 40, 8.
[0010] The first data processing device/data
processing method of the present technology performs
group-wise interleave of interleaving in a 360-bit group
unit the LDPC code whose code length is 64800 bits and
code rate is 10/15, 11/15, 12/15 or 13/15. In the group-
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wise interleave, the sequence of the 64800 bits of the
LDPC code bit group 0 to 179 is interleaved into the
following sequence of the bit group:
178, 140, 44, 100, 107, 89, 169, 166, 36, 52, 33, 160, 14,
165, 109, 35, 74, 136, 99, 97, 28, 59, 7, 29, 164, 119,
41, 55, 17, 115, 138, 93, 96, 24, 31, 179, 120, 91, 98,
43, 6, 56, 148, 68, 45, 103, 5, 4, 10, 58, 1, 76, 112,
124, 110, 66, 0, 85, 64, 163, 75, 105, 117, 87, 159, 146,
34, 57, 145, 143, 101, 53, 123, 48, 79, 13, 134, 71, 135,
81, 125, 30, 131, 139, 46, 12, 157, 23, 127, 61, 82, 84,
32, 22, 94, 170, 167, 126, 176, 51, 102, 171, 18, 104, 73,
152, 72, 25, 83, 80, 149, 142, 77, 137, 177, 19, 20, 173,
153, 54, 69, 49, 11, 156, 133, 162, 63, 122, 106, 42, 174,
88, 62, 78, 86, 116, 155, 129, 3, 9, 47, 50, 144, 114,
154, 121, 161, 92, 37, 38, 39, 108, 95, 70, 113, 141, 15,
147, 151, 111, 2, 118, 158, 60, 132, 168, 150, 21, 16,
175, 27, 90, 128, 130, 67, 172, 65, 26, 40, 8.
[0011] The second data processing device/data
processing method of the present technology includes a
group-wise interleave unit of performing group-wise
interleave of interleaving in a 360-bit group unit an
LDPC code whose code length is 64800 bits and code rate
is 10/15, 11/15, 12/15 or 13/15, and a group-wise
deinterleave unit/step of returning a sequence of the
LDPC code after the group-wise interleave obtained from
data transmitted from a transmitting device to the
original sequence, the (i + 1)th bit group from the
beginning of the LDPC code of the 64800 bits being as a
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bit group i, and in the group-wise interleave, a sequence
of bit group 0 to 179 of the 64800 bits of the LDPC code
being interleaved into the following sequence of the bit
group:
5 178, 140, 44, 100, 107, 89, 169, 166, 36, 52, 33, 160, 14,
165, 109, 35, 74, 136, 99, 97, 28, 59, 7, 29, 164, 119,
41, 55, 17, 115, 138, 93, 96, 24, 31, 179, 120, 91, 98,
43, 6, 56, 148, 68, 45, 103, 5, 4, 10, 58, 1, 76, 112,
124, 110, 66, 0, 85, 64, 163, 75, 105, 117, 87, 159, 146,
34, 57, 145, 143, 101, 53, 123, 48, 79, 13, 134, 71, 135,
81, 125, 30, 131, 139, 46, 12, 157, 23, 127, 61, 82, 84,
32, 22, 94, 170, 167, 126, 176, 51, 102, 171, 18, 104, 73,
152, 72, 25, 83, 80, 149, 142, 77, 137, 177, 19, 20, 173,
153, 54, 69, 49, 11, 156, 133, 162, 63, 122, 106, 42, 174,
88, 62, 78, 86, 116, 155, 129, 3, 9, 47, 50, 144, 114,
154, 121, 161, 92, 37, 38, 39, 108, 95, 70, 113, 141, 15,
147, 151, 111, 2, 118, 158, 60, 132, 168, 150, 21, 16,
175, 27, 90, 128, 130, 67, 172, 65, 26, 40, 8.
[0012] The second data processing device/data
processing method of the present technology includes a
group-wise interleave unit of performing group-wise
interleave of interleaving in a 360-bit group unit an
LDPC code whose code length is 64800 bits and code rate
is 10/15, 11/15, 12/15 or 13/15, and of returning the
sequence of the LDPC code after the group-wise interleave
obtained from data transmitted from a transmitting device
to the original sequence, the (i + 1)th bit group from
the beginning of the LDPC code of the 64800 bits being as
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a bit group i, and in the group-wise interleave, a
sequence of bit group 0 to 179 of the 64800 bits of the
LDPC code being interleaved into the following sequence
of the bit group:
178, 140, 44, 100, 107, 89, 169, 166, 36, 52, 33, 160, 14,
165, 109, 35, 74, 136, 99, 97, 28, 59, 7, 29, 164, 119,
41, 55, 17, 115, 138, 93, 96, 24, 31, 179, 120, 91, 98,
43, 6, 56, 148, 68, 45, 103, 5, 4, 10, 58, 1, 76, 112,
124, 110, 66, 0, 85, 64, 163, 75, 105, 117, 87, 159, 146,
34, 57, 145, 143, 101, 53, 123, 48, 79, 13, 134, 71, 135,
81, 125, 30, 131, 139, 46, 12, 157, 23, 127, 61, 82, 84,
32, 22, 94, 170, 167, 126, 176, 51, 102, 171, 18, 104, 73,
152, 72, 25, 83, 80, 149, 142, 77, 137, 177, 19, 20, 173,
153, 54, 69, 49, 11, 156, 133, 162, 63, 122, 106, 42, 174,
88, 62, 78, 86, 116, 155, 129, 3, 9, 47, 50, 144, 114,
154, 121, 161, 92, 37, 38, 39, 108, 95, 70, 113, 141, 15,
147, 151, 111, 2, 118, 158, 60, 132, 168, 150, 21, 16,
175, 27, 90, 128, 130, 67, 172, 65, 26, 40, 8.
[0013] The data processing apparatus may be an
independent apparatus or may be an internal block making
up one device.
Effects of the Invention
[0014] According to the present technology, in the
data transmission using the LDPC code, it is possible to
ensure good communication quality.
[0015] Here, the effects described in are not
necessarily limited, it may be any of the effects
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described in the present disclosure.
Brief Description of Drawings
[0016]
[Fig. 1] A diagram illustrating a parity check matrix H
of an LDPC code.
[Fig. 2] A flowchart illustrating a decoding procedure
of an LDPC code.
[Fig. 3] A diagram illustrating an example of an LDPC
code of the parity check matrix.
[Fig. 4] A diagram illustrating a Tanner graph of the
parity check matrix.
[Fig. 5] A diagram showing a variable node.
[Fig. 6] A diagram showing a check node.
[Fig. 7] A diagram illustrating an example configuration
of an embodiment of a transmission system to which the
present technology is applied.
[Fig. 8] A block diagram showing a configuration example
of the transmitting apparatus 11.
[Fig. 9] A block diagram showing a configuration example
of the bit interleaver 116.
[Fig. 10] A diagram illustrating a parity check matrix
[Fig. 11] A diagram illustrating a parity matrix.
[Fig. 12] A diagram illustrating a parity check matrix of
an LDPC code prescribed in the standard of the DVB-T.2.
[Fig. 13] A diagram illustrating a parity check matrix of
an LDPC code prescribed in the standard of the DVB-T.2.
[Fig. 14] A diagram illustrating a Tanner graph for
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decoding of LDPC codes.
[Fig. 15] A diagram showing a parity matrix HT having a
staircase structure and a diagram illustrating a Tanner
graph corresponding to the parity matrix HT.
[Fig. 16] A diagram illustrating a parity matrix HT of the
parity check matrix H corresponding to the LDPC code
after the parity interleave.
[Fig. 17] A flowchart for explaining the processing
performed by a bit interleaver 116 and a mapper 117.
[Fig. 18] A block diagram showing a configuration example
of an LDPC encoder 115.
[Fig. 19] A flowchart illustrating a process of the LDPC
encoder 115.
[Fig. 20] A diagram illustrating an example of a parity
check matrix initial value table of a code rate of 1/4
and a code length of 16200.
[Fig. 21] A diagram for explaining a method of
determining a parity check matrix H from the parity check
matrix initial value table.
[Fig. 22] A diagram showing a parity check matrix initial
value table of a first new LDPC code whose code length N
is 64k bits and code rate r is 7/15.
[Fig. 23] A diagram showing a parity check matrix initial
value table of a first new LDPC code whose code length N
is 64k bits and code rate r is 7/15.
[Fig. 24] A diagram showing a parity check matrix initial
value table of a first new LDPC code whose code length N
is 64k bits and code rate r is 7/15.
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[Fig. 25] A diagram showing a parity check matrix initial
value table of a first new LDPC code whose code length N
is 64k bits and code rate r is 9/15.
[Fig. 26] A diagram showing a parity check matrix initial
value table of a first new LDPC code whose code length N
is 64k bits and code rate r is 9/15.
[Fig. 27] A diagram showing a parity check matrix initial
value table of a first new LDPC code whose code length N
is 64k bits and code rate r is 9/15.
[Fig. 28] A diagram showing a parity check matrix initial
value table of a first new LDPC code whose code length N
is 64k bits and code rate r is 11/15.
[Fig. 29] A diagram showing a parity check matrix initial
value table of a first new LDPC code whose code length N
is 64k bits and code rate r is 11/15.
[Fig. 30] A diagram showing a parity check matrix initial
value table of a first new LDPC code whose code length N
is 64k bits and code rate r is 11/15.
[Fig. 31] A diagram showing a parity check matrix initial
value table of a first new LDPC code whose code length N
is 64k bits and code rate r is 13/15.
[Fig. 32] A diagram showing a parity check matrix initial
value table of a first new LDPC code whose code length N
is 64k bits and code rate r is 13/15.
[Fig. 33] A diagram showing a parity check matrix initial
value table of a first new LDPC code whose code length N
is 64k bits and code rate r is 13/15.
[Fig. 34] A diagram showing a parity check matrix initial
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value table of a first new LDPC code whose code length N
is 16k bits and code rate r is 6/15.
[Fig. 35] A diagram showing a parity check matrix initial
value table of a first new LDPC code whose code length N
5 is 16k bits and code rate r is 8/15.
[Fig. 36] A diagram showing a parity check matrix initial
value table of a first new LDPC code whose code length N
is 16k bits and code rate r is 10/15.
[Fig. 37] A diagram showing a parity check matrix initial
10 value table of a first new LDPC code whose code length N
is 16k bits and code rate r is 12/15.
[Fig. 38] A diagram showing a parity check matrix initial
value table of a first other new LDPC code whose code
length N is 16k bits and code rate r is 10/15.
[Fig. 39] A diagram showing a parity check matrix initial
value table of a first other new LDPC code whose code
length N is 16k bits and code rate r is 12/15.
[Fig. 40] A diagram showing a parity check matrix initial
value table of a second new LDPC code whose code length N
is 64k bits and code rate r is 6/15.
[Fig. 41] A diagram showing a parity check matrix initial
value table of a second new LDPC code whose code length N
is 64k bits and code rate r is 6/15.
[Fig. 42] A diagram showing a parity check matrix initial
value table of a second new LDPC code whose code length N
is 64k bits and code rate r is 8/15.
[Fig. 43] A diagram showing a parity check matrix initial
value table of a second new LDPC code whose code length N
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is 64k bits and code rate r is 8/15.
[Fig. 44] A diagram showing a parity check matrix initial
value table of a second new LDPC code whose code length N
is 64k bits and code rate r is 8/15.
[Fig. 45] A diagram showing a parity check matrix initial
value table of a second new LDPC code whose code length N
is 64k bits and code rate r is 10/15.
[Fig. 46] A diagram showing a parity check matrix initial
value table of a second new LDPC code whose code length N
is 64k bits and code rate r is 10/15.
[Fig. 47] A diagram showing a parity check matrix initial
value table of a second new LDPC code whose code length N
is 64k bits and code rate r is 10/15.
[Fig. 48] A diagram showing a parity check matrix initial
value table of a second new LDPC code whose code length N
is 64k bits and code rate r is 12/15.
[Fig. 49] A diagram showing a parity check matrix initial
value table of a second new LDPC code whose code length N
is 64k bits and code rate r is 12/15.
[Fig. 50] A diagram showing a parity check matrix initial
value table of a second new LDPC code whose code length N
is 64k bits and code rate r is 12/15.
[Fig. 51] A diagram showing a parity check matrix initial
value table of a second new LDPC code whose code length N
is 16k bits and code rate r is 7/15.
[Fig. 52] A diagram showing a parity check matrix initial
value table of a second new LDPC code whose code length N
is 16k bits and code rate r is 9/15.
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[Fig. 53] A diagram showing a parity check matrix initial
value table of a second new LDPC code whose code length N
is 16k bits and code rate r is 11/15.
[Fig. 54] A diagram showing a parity check matrix initial
value table of a second new LDPC code whose code length N
is 16k bits and code rate r is 13/15.
[Fig. 55] A diagram illustrating an example of a Tanner
graph of an ensemble of a degree sequence in which a
column weight is 3 and a row weight is 6.
[Fig. 56] A diagram showing an example of the Tanner
graph of a multi-edge type ensemble.
[Fig. 57] A diagram showing a minimum cycle length and a
performance threshold of the parity check matrix of the
first new LDPC code whose code length N is 64k bits and
code rate r is 7/15, 9/15, 11/15 or 13/15.
[Fig. 58] A diagram showing a minimum cycle length and a
performance threshold of the parity check matrix of the
first new LDPC code whose code length N is 64k bits and
code rate r is 7/15, 9/15, 11/15 or 13/15.
[Fig. 59] A diagram showing a minimum cycle length and a
performance threshold of the parity check matrix of the
first new LDPC code whose code length N is 64k and code
rate r is 7/15, 9/15, 11/15 or 13/15.
[Fig. 60] A diagram showing a simulation result of
measurement of BER/FER about the first new LDPC code
whose code length N is 64k bits and code rate r is 7/15.
[Fig. 61] A diagram showing a simulation result of
measurement of BER/FER about the first new LDPC code
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whose code length N is 64k bits and code rate r is 9/15.
[Fig. 62] A diagram showing a simulation result of
measurement of BER/FER about the first new LDPC code
whose code length N is 64k bits and code rate r is 11/15.
[Fig. 63] A diagram showing a simulation result of
measurement of BER/FER about the first new LDPC code
whose code length N is 64k bits and code rate r is 13/15.
[Fig. 64] A diagram showing a minimum cycle length and a
performance threshold of the parity check matrix of the
first new LDPC code whose code length N is 16k bits and
code rate r is 6/15, 8/15, 10/15 or 12/15.
[Fig. 65] A diagram illustrating the parity check matrix
of the first new LDPC code whose code length N is 16k
bits and code rate r is 6/15, 8/15, 10/15 or 12/15.
[Fig. 66] A diagram illustrating the parity check matrix
of the first new LDPC code whose code length N is 16k
bits and code rate r is 6/15, 8/15, 10/15 or 12/15.
[Fig. 67] A diagram showing a simulation result of
measurement of BER/FER about the first new LDPC code
whose code length N is 64k bits and code rate r is 6/15.
[Fig. 68] A diagram showing a simulation result of
measurement of BER/FER about the first new LDPC code
whose code length N is 64k bits and code rate r is 8/15.
[Fig. 69] A diagram showing a simulation result of
measurement of BER/FER about the first new LDPC code
whose code length N is 64k bits and code rate r is 10/15.
[Fig. 70] A diagram showing a simulation result of
measurement of BER/FER about the first new LDPC code
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whose code length N is 64k bits and code rate r is 12/15.
[Fig. 71] A diagram showing a minimum cycle length and a
performance threshold of the parity check matrix of the
first other new LDPC code whose code length N is 16k bits
and code rate r is 10/15.
[Fig. 72] A diagram showing a minimum cycle length and a
performance threshold of the parity check matrix of the
first other new LDPC code whose code length.N is 16k bits
and code rate r is 10/15.
[Fig. 73] A diagram showing a minimum cycle length and a
performance threshold of the parity check matrix of the
first other new LDPC code whose code length N is 16k bits
and code rate r is 10/15.
[Fig. 74] A diagram showing a simulation result of
measurement of BER/FER about the first other new LDPC
code whose code length N is 16k bits and code rate r is
10/15.
[Fig. 75] A diagram showing a simulation result of
measurement of BER/FER about the first other new LDPC
code whose code length N is 16k bits and code rate r is
12/15.
[Fig. 76] A diagram illustrating the parity check matrix
of the first other new LDPC code whose code length N is
16k bits and code rate r is 12/15.
[Fig. 77] A diagram illustrating the parity check matrix
of the first other new LDPC code whose code length N is
16k bits and code rate r is 12/15.
[Fig. 78] A diagram showing a simulation result of
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measurement of BER/FER about the first other new LDPC
code whose code length N is 16k bits and code rate r is
12/15.
[Fig. 79] A diagram illustrating the parity check matrix
5 of the second new LDPC code whose code length N is 64k
bits and code rate r is 6/15, 8/15, 10/15, 12/15.
[Fig. 80] A diagram illustrating the parity check matrix
of the second new LDPC code whose code length N is 64k
bits and code rate r is 6/15, 8/15, 10/15, 12/15.
10 [Fig. 81] A diagram showing a simulation result of
measurement of BER/FER about the second new LDPC code
whose code length N is 64k bits and code rate r is 6/15.
[Fig. 82] A diagram showing a simulation result of
measurement of BER/FER about the second new LDPC code
15 whose code length N is 64k bits and code rate r is 8/15.
[Fig. 83] A diagram showing a simulation result of
measurement of BER/FER about the second new LDPC code
whose code length N is 64k bits and code rate r is 10/15.
[Fig. 84] A diagram showing a simulation result of
measurement of BER/FER about the second new LDPC code
whose code length N is 64k bits and code rate r is 12/15.
[Fig. 85] A diagram illustrating the parity check matrix
of the second new LDPC code whose code length N is 16k
bits and code rate r is 7/15, 9/15, 11/15, 13/15.
[Fig. 86] A diagram illustrating the parity check matrix
of the second new LDPC code whose code length N is 16k
bits and code rate r is 7/15, 9/15, 11/15, 13/15.
[Fig. 87] A diagram showing a simulation result of
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measurement of BER/FER about the second new LDPC code
whose code length N is 16k bits and code rate r is 7/15.
[Fig. 88] A diagram showing a simulation result of
measurement of BER/FER about the second new LDPC code
whose code length N is 16k bits and code rate r is 9/15.
[Fig. 89] A diagram showing a simulation result of
measurement of BER/FER about the second new LDPC code
whose code length N is 16k bits and code rate r is 11/15.
[Fig. 90] A diagram showing a simulation result of
measurement of BER/FER about the second new LDPC code
whose code length N is 16k bits and code rate r is 13/15.
[Fig. 91] A diagram showing illustrative types of the
constellation.
[Fig. 92] A diagram showing an example of a constellation
for eight code rates r of the LDPC code when the
modulation scheme is 16QAM.
[Fig. 93] A diagram showing an example of a constellation
for eight code rates r of the LDPC code when the
modulation scheme is 64QAM.
[Fig. 94] A diagram showing an example of a constellation
for eight code rates r of the LDPC code when the
modulation scheme is 256QAM.
[Fig. 95] A diagram showing an example of a constellation
for eight code rates r of the LDPC code when the
modulation scheme is 1024QAM.
[Fig. 96] A diagram showing a simulation result of
measurement of BER where UC, 1D NUC or 2D NUC is used as
constellation when the modulation scheme is 16QAM.
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[Fig. 97] A diagram showing a simulation result of
measurement of BER where UC, 1D NUC or 2D NUC is used as
constellation when the modulation scheme is 64QAM.
[Fig. 98] A diagram showing a simulation result of
measurement of BER where UC, 1D NUC or 2D NUC is used as
constellation when the modulation scheme is 256QAM.
[Fig. 99] A diagram showing a simulation result of
measurement of BER where UC, 1D NUC or 2D NUC is used as
constellation when the modulation scheme is 1024QAM.
[Fig. 100] A diagram showing coordinates of the
signal points of UC commonly used for eight code rates r
of the LDPC code when the modulation scheme is QPSK.
[Fig. 101] A diagram showing coordinates of the
signal points of 2D NUC commonly used for eight code
rates r of the LDPC code when the modulation scheme is
16QAM.
[Fig. 102] A diagram showing coordinates of the
signal points of 2D NUC commonly used for eight code
rates r of the LDPC code when the modulation scheme is
64QAM.
[Fig. 103] A diagram showing coordinates of the
signal points of 2D NUC commonly used for eight code
rates r of the LDPC code when the modulation scheme is
256QAM.
[Fig. 104] A diagram showing coordinates of the
signal points of 1D NUC commonly used for eight code
rates r of the LDPC code when the modulation scheme is
1024QAM.
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[Fig. 105] A diagram showing a relationship between a
real part Re(zq) and an imaginary part Im(zq) of a
complex number as a coordinate of a symbol y and a signal
point zq of 1D NUC corresponding to the symbol y.
[Fig. 106] A block diagram showing a configuration
example of a block interleaver 25.
[Fig. 107] A diagram showing a column number C of
parts 1 and 2 for a combination of a code length N and a
modulation scheme and part column lengths R1 and R2.
[Fig. 108] A diagram for illustrating a block
interleave performed in the block interleaver 25.
[Fig. 109] A diagram for illustrating group-wise
interleave performed in a group-wise interleaver 24.
[Fig. 110] A diagram showing a first example of a GW
pattern for the LDPC code whose code length N is 64k bits.
[Fig. 111] A diagram showing a second example of the
GW pattern for the LDPC code whose code length N is 64k
bits.
[Fig. 112] A diagram showing a third example of the
GW pattern for the LDPC code whose code length N is 64k
bits.
[Fig. 113] A diagram showing a fourth example of the
GW pattern for the LDPC code whose code length N is 64k
bits.
[Fig. 114] A diagram showing a first example of a GW
pattern for the LDPC code whose code length N is 16k bits.
[Fig. 115] A diagram showing a second example of the
GW pattern for the LDPC code whose code length N is 16k
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bits.
[Fig. 116] A diagram showing a third example of the GW
pattern for the LDPC code whose code length N is 16k bits.
[Fig. 117] A diagram showing a fourth example of the
GW pattern for the LDPC code whose code length N is 16k bits.
[Fig. 118] A block diagram showing a configuration
example of the receiving device 12.
[Fig. 119] A block diagram showing a configuration
example of a bit deinterleaver 165.
[Fig. 120] A flowchart illustrating processes
performed by a demapper 164, the bit deinterleaver 165,
and an LDPC decoder 166.
[Fig. 121] A diagram showing an example of the parity
check matrix of the LDPC code.
[Fig. 122] A diagram illustrating a matrix
(conversion parity check matrix) obtained by applying row
permutation and column permutation to the parity check
matrix.
[Fig. 123] A diagram illustrating the conversion
parity check matrix divided into 5 x 5 units.
[Fig. 124] A block diagram showing a configuration
example of a decoding device, which collectively performs
P node operations.
[Fig. 125] A block diagram showing a configuration
example of the LDPC decoder 166.
[Fig. 126] A block diagram showing a configuration
example of a block deinterleaver 54.
[Fig. 127] A block diagram showing other
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configuration example of the bit deinterleaver 165.
[Fig. 128] A block diagram showing a first
configuration example of a receiving system to which the
receiving device 12 may be applied.
5 [Fig. 129] A block diagram showing a second
configuration example of the receiving system to which
the receiving device 12 may be applied.
[Fig. 130] A block diagram showing a third
configuration example of the receiving system to which
10 the receiving device 12 may be applied.
[Fig. 131] A block diagram showing a configuration
example of one embodiment of a computer to which the
present technology is applied.
Modes for Carrying Out the Invention
15 [0017] Hereinafter, embodiments of the present
technology will be described. Before that, an LDPC code
will be described.
[0018]
<LDPC code>
20 [0019] The LDPC code is a linear code and is not
necessarily required to be a binary code; however, it is
herein described supposing that this is the binary code.
[0020] The greatest characteristic of the LDPC code is
that a parity check matrix defining the LDPC code is
sparse. Herein, the sparse matrix is the matrix in which
the number of elements "1" of the matrix is very small
(most of elements are 0).
[0021] Fig. 1 is a view showing an example of a parity
CA 02924874 2016-03-18
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check matrix H of the LDPC code.
[0022] In the parity check matrix H in Fig. 1, a
weight of each column (column weight) (the number of "1")
is "3" and the weight of each row (row weight) is "6".
[0023] In encoding by the LDPC code (LDPC encoding), a
code word (LDPC code) is generated by generation of a
generator matrix G based on the parity check matrix H and
multiplication of the generator matrix G by a binary
information bit, for example.
[0024] Specifically, an encoding device, which
performs the LDPC encoding, first calculates the
generator matrix G satisfying an equation GHT = 0 between
the same and a transposed matrix HT ofthe parity check
matrix H. Herein, when the generator matrixGisaKxN
matrix, the encoding device multiplies a bit column
(vector u) of K bits by the generator matrix G to
generate a code word c (= uG) configured of N bits. The
code word (LDPC code) generated by the encoding device is
received on a receiving side through a predetermined
communication channel.
[0025] Decoding of the LDPC code may be performed by
an algorithm suggested by Gallager as probabilistic
decoding being a message passing algorithm by belief
propagation on a so-called Tanner graph configured of a
variable node (also referred to as a message node) and a
check node. Hereinafter, the variable node and the check
node are appropriately and simply referred to as a node.
[0026] Fig. 2 is a flowchart showing a procedure of
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the decoding of the LDPC code.
[0027] A real value (received LLR) representing
likelihood of a value to be "0" of an i-th code bit of
the LDPC code (one cord word) received on the receiving
side by a log likelihood ratio is hereinafter
appropriately referred to as a received value un. A
message output from the check node is set to ujand the
message output from the variable node is set to vi.
[0028] First, in the decoding of the LDPC code, as
shown in Fig. 2, the LDPC code is received, the message
(check node message) ujis initialized to "0", and a
variable k being an integer as a counter of a repetitive
process is initialized to "0" at step Sll and the
procedure shifts to step S12. At step S12, the message
(variable node message) vi is obtained by an operation
(variable node operation) represented in equation (1)
based on the received value un obtained by receiving the
LDPC code and the message uj is obtained by an operation
(check node operation) represented in equation (2) based
on the message vi.
[0029]
[Equation 1]
Vi=Uoi Uj
j=1 (1)
[0030]
[Equation 2]
dc-1
i Vi
tanh(---U -2¨)= tanh( __ 2 )
i=1 (2)
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[0031] Herein, d, and dc in equations (1) and (2) are
parameters indicating the numbers of "1" in a vertical
direction (column) and a horizontal direction (row) of
the parity check matrix H, which may be optionally
selected. For example, it is set that dv = 3 and dc = 6
in the case of the LDPC code ((3, 6) LDPC code) for the
parity check matrix H in which the column weight is 3 and
the row weight is 6 as shown in Fig. 1.
[0032] In the variable node operation in equation (1)
and the check node operation in equation (2), the message
input from an edge (line connecting the variable node and
the check node to each other) from which the message is
to be output is not a target of the operation, so that a
range of the operation is 1 to dv-1 or 1 to dc-1. Also, a
table of a function R(vi, v2) represented in equation (3)
defined by one output with respect to two inputs viand v2
is created in advance and this is continuously
(recursively) used as represented in equation (4) for
actually performing the check node operation in equation
(2).
[0033]
[Equation 3]
x=2tanh-1 (tanh (v1/2) tanh (v2/2) } =R (vi , v2) (3)
[0034]
Ui =R (vi, R (v2, R (v3, " .13 (Vdc-2, Vdc-i) )) )
(4)
[0035] At step S12, the variable k is incremented by 1
CA 02924874 2016-03-18
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and the procedure shifts to step S13. At step S13, it is
judged whether the variable k is larger than a
predetermined number of times of repetitive decoding C.
When it is judged that the variable k is not larger than
C at step S13, the procedure returns to step S12 and a
similar process is hereinafter repeatedly performed.
[0036] Also, when it is judged that the variable k is
larger than C at step S13, the procedure shifts to step
S14 to perform an operation represented in equation (5),
so that the message vi as a decoding result to be finally
output is obtained to be output and a decoding process of
the LDPC code is finished.
[0037]
[Equation 5]
Uj
j=1 (5)
[0038] Herein, different from the variable node
operation in equation (1), the operation in equation (5)
is performed using the messages uj from all the edges
connected to the variable node.
[0039] Fig. 3 is a view showing an example of the
parity check matrix H of the (3, 6) LDPC code (code rate
1/2 and code length 12).
[0040] In the parity check matrix H in Fig. 3, the
weight of the column is 3 and the weight of the row is 6
as in Fig. 1.
[0041] Fig. 4 is a view showing the Tanner graph of
the parity check matrix H in Fig. 3.
CA 02924874 2016-03-18
[0042] Herein, in Fig. 4, the check node is
represented by plus "+" and the variable node is
represented by equal "=". The check node and the variable
node correspond to the row and the column of the parity
5 check matrix H, respectively. A connection between the
check node and the variable node is the edge, which
corresponds to the element "1" of the parity check matrix.
[0043] That is to say, when a j-th row i-th column
element of the parity check matrix is 1, in Fig. 4, an i-
10 th variable node (node of "=") from the top and a j-th
check node (node of "+") from the top are connected to
each other by the edge. The edge indicates that the code
bit corresponding to the variable node has a constraint
condition corresponding to the check node.
15 [0044] In a sum product algorithm being the decoding
method of the LDPC code, the variable node operation and
the check node operation are repeatedly performed.
[0045] Fig. 5 is a view showing the variable node
operation performed in the variable node.
20 [0046] In the variable node, the message vi
corresponding to the edge to be calculated is obtained by
the variable node operation in equation (1) using the
messages uland U2 from other edges connected to the
variable node and the received value un. The message
25 corresponding to another edge is similarly obtained.
[0047] Fig. 6 illustrates the check node operation
performed in the check node.
[0048] Herein, the check node operation in equation
CA 02924874 2016-03-18
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(2) may be rewritten as equation (6) using relationship
of an equation a x b = expfln(la1)+1n(lb1)1 x sign(a) x
sign(b). Sign(x) is 1 when x => 0 is satisfied and -1
when x < 0 is satisfied.
[0049]
[Equation 6]
(dc-1
uj =2tanh-1 fl tanh
2 I
dc-1 d
=2tanh-1 exp I n ( tanhE-1-v ) xc-1 s gn (tanh
=1 2 i =1
dc-1
=2tanh-1 exp {¨ ( ¨ I n (tanh Ivi 2 )\ \I c10-1
X TT sign(vi)
i =1 jj i=1
(6)
[0050] When a function (p) (x) is defined by an
equation (1)(x) = ln(tan h(x/2)) when x => 0 is satisfied,
an equation (1)-1(x) = 2 tan h(e) is satisfied, so that
equation (6) may be deformed to equation (7).
[0051]
[Equation 7]
(dc-1 dc-1
L11=0-1 (IVi I) X 7 sign(vi)
i=1 i=1
(7)
[0052] In the check node, the check node operation in
equation (2) is performed according to equation (7).
[0053] That is to say, in the check node, the message
u3 corresponding to the edge to be calculated is obtained
by the check node operation in equation (7) using
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messages vu v2, v3, v4, and V5 from other edges connected
to the check node as illustrated in Fig. 6. The message
corresponding to another edge is similarly obtained.
[0054] The function p(x) in equation (7) may be
represented by an equation p(x) = ln((ex+1)/(ex-1)) and
p(x) = p-1(x) when x > 0 is satisfied. When the functions
p(x) and p-1(x) are implemented in hardware, there is a
case in which they are implemented using LUT (look up
table), and the same LUT is used for both of them.
[0055]
<Configuration example of transmission system to which
the present technology is applied>
[0056] Fig. 7 illustrates a configuration example of
one embodiment of a transmission system (the term
"system" is intended to mean a logical assembly of a
plurality of devices and it does not matter whether the
devices of each configuration are in the same housing) to
which the present technology is applied.
[0057] In Fig. 7, the transmission system is
configured of a transmitting device 11 and a receiving
device 12.
[0058] The transmitting device 11 transmits
(broadcasts) (transmits) a program of television
broadcasting. That is to say, the transmitting device 11
encodes target data to be transmitted such as image data
and audio data as the program, for example, into an LDPC
code and transmits the same through a communication
channel 13 such as a satellite circuit, a terrestrial
CA 02924874 2016-03-18
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wave, and a cable (wire circuit).
[0059] The receiving device 12 receives the LDPC code
transmitted from the transmitting device 11 through the
communication channel 13 and decodes the same to the
target data to output.
[0060] Herein, it is known that the LDPC code used in
the transmission system in Fig. 7 exhibits an extremely
high ability in an AWGN (additive white Gaussian noise)
communication channel.
[0061] However, a burst error and erasure might occur
in the communication channel 13 such as the terrestrial
wave. For example, especially when the communication
channel 13 is a terrestrial wave, in an OFDM (orthogonal
frequency division multiplexing) system, there is a case
in which power of a specific symbol reaches 0 (erasure)
according to delay of an echo (a path other than a main
path) in a multipath environment in which a D/U (desired
to undesired ratio) is 0 dB (power of undesired (= echo)
is equal to power of desired (= main path)).
[0062] There is a case in which the power of all the
symbols of the OFDM at a specific time reaches 0
(erasure) by a Doppler frequency when the D/U is 0 dB
also in a flutter (communication channel in which a
Doppler frequency-shifted echo whose delay is 0 is added).
[0063] Further, the burst error might occur due to a
wiring status from a receiver (not shown) such as an
antenna, which receives a signal from the transmitting
device 11, to the receiving device 12 and instability of
CA 02924874 2016-03-18
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a power supply of the receiving device 12 on a side of
the receiving device 12.
[0064] On the other hand, in decoding of the LDPC code,
a variable node operation in equation (1) including
addition of (a received value uoi of) a code bit of the
LDPC code is performed as illustrated above in Fig. 5 in
a variable node corresponding to a column of a parity
check matrix H and eventually the code bit of the LDPC
code, so that, when the error occurs in the code bit used
in the variable node operation, accuracy of an obtained
message is deteriorated.
[0065] In the decoding of the LDPC code, a check node
operation in equation (7) is performed in the check node
using the message obtained in the variable node connected
to the check node, so that decoding performance is
deteriorated when the number of check nodes, in which
(the code bits of the LDPC code corresponding to) a
plurality of variable nodes connected thereto have the
error (including the erasure) at the same time, increases.
[0066] That is to say, when the erasure occurs in two
or more of the variable nodes connected to the check node
at the same time, the check node returns the message
indicating that probability that the value is 0 and the
probability that the value is 1 are equal to all the
variable nodes, for example. In this case, the check node,
which returns the message of the equal probability, does
not contribute to a single decoding process (one set of
the variable node operation and the check node operation),
CA 02924874 2016-03-18
and as a result, this requires a large number of
repetitions of the decoding process, so that the decoding
performance is deteriorated and further, power
consumption of the receiving device 12, which decodes the
5 LDPC code, increases.
[0067] Therefore, the transmission system in Fig. 7 is
configured to improve resistance to burst error and
erasure while maintaining performance in the AWGN
communication channel (AWGN channel).
10 [0068]
[Configuration example of transmitting device 11]
[0069] Fig. 8 is a block diagram showing a
configuration example of the transmitting device 11 in
Fig. 7.
15 [0070] In the transmitting device 11, one or more
input streams as the target data are supplied to a mode
adaptation/multiplexer 111.
[0071] The mode adaptation/multiplexer 111 selects a
mode, multiplexes the one or more input streams supplied
20 thereto, and supplies the data obtained as a result to a
padder 112.
[0072] The padder 112 performs necessary zero padding
(null insertion) to the data from the mode
adaptation/multiplexer 111 and supplies the data obtained
25 as a result to a BB scrambler 113.
[0073] The BB scrambler 113 applies BB scramble (Base-
Band Scrambling) to the data from the padder 112 and
supplies the data obtained as a result to a BCH encoder
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114.
[0074] The BCH encoder 114 performs BCH encoding of
the data from the BB scrambler 113 and supplies the data
obtained as a result to an LDPC encoder 115 as LDPC
target data being a target of LDPC encoding.
[0075] The LDPC encoder 115 performs the LDPC encoding
of the LDPC target data from the BCH encoder 114
according to a parity check matrix in which a parity
matrix being a part corresponding to a parity bit of the
LDPC code has a stepwise structure and outputs the LDPC
code in which an information bit is the LDPC target data.
[0076] That is to say, the LDPC encoder 115 performs
the LDPC encoding to encode the LDPC target data into the
LDPC code (corresponding to the parity check matrix) such
as the LDPC code specified in a predetermined standard
such as a DVB-S.2 standard, a DVB-T.2 standard and a DVB-
C.2 standard or the LDPC code expected to be specified by
ATSC3.0 (corresponding to the parity check matrix), for
example, and outputs the LDPC code obtained as a result.
[0077] In the LDPC code specified in the DVB-T.2
standard or the LDPC code expected to be specified by
ATSC3.0 is an IRA (irregular repeat-accumulate) code and
the parity matrix in the parity check matrix of the LDPC
code has the stepwise structure. The parity matrix and
the stepwise structure are described later. The IRA code
is described in "Irregular Repeat-Accumulate Codes, " H.
Jin, A. Khandekar, and R. J. McEliece, in Proceedings of
2nd International Symposium on Turbo Codes and Related
CA 02924874 2016-03-18
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Topics, pp. 1-8, Sept. 2000, for example.
[0078] The LDPC code output by the LDPC encoder 115 is
supplied to a bit interleaver 116.
[0079] The bit interleaver 116 performs bit interleave
to be described later of the LDPC code from the LDPC
encoder 115 and supplies the LDPC code after the bit
interleave to a mapper 117.
[0080] The mapper 117 maps the LDPC code from the bit
interleaver 116 onto a signal point indicating one symbol
of orthogonal modulation in units of one or more code
bits of the LDPC code (symbol unit) to perform the
orthogonal modulation (multilevel modulation).
[0081] That is to say, the mapper 117 maps the LDPC
code from the bit interleaver 116 onto the signal point
defined by a modulation scheme for performing the
orthogonal modulation of the LDPC code on an IQ plane (IQ
constellation) defined by an I axis representing an I
component in phase with a carrier wave and a Q axis
representing a Q component orthogonal to the carrier wave
and performs the orthogonal modulation.
[0082] If the number of signal points prescribed by
orthogonal modulation of a modulation scheme which is
performed by the mapper 117 is 2m, the mapper 117 maps the
LDPC code from the bit interleaver 116 in a symbol unit
onto the signal point indicating the symbol of the 2m
signal points as the m code bit of the LDPC code for a
symbol (1 symbol).
[0083] Herein, the modulation scheme of the orthogonal
CA 02924874 2016-03-18
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modulation performed by the mapper 117 includes the
modulation scheme including the modulation scheme
specified in the DVB-T.2 standard, for example, the
modulation scheme expected to be specified by ATSC3.0,
and other modulation schemes, that is to say, BPSK
(Binary Phase Shift Keying), QPSK (quadrature phase shift
keying), 8PSK (Phase-Shift Keying), 16APSK (Amplitude
Phase-Shift Keying), 32APSK, 16QAM (quadrature amplitude
modulation), 16QAM, 64QAM, 256QAM, 1024QAM, 4096QAM, 4PAM
(Pulse Amplitude Modulation) and the like, for example.
The modulation scheme with which the orthogonal
modulation is performed by the mapper 117 is set in
advance according to operation of an operator of the
transmitting device 11, for example.
[0084] The data (symbol mapped onto the signal point)
obtained by the process by the mapper 117 is supplied to
a time interleaver 118.
[0085] The time interleaver 118 performs time
interleave (interleave in a time direction) in a symbol
unit of the data from the mapper 117 and supplies the
data obtained as a result to a SISO/MISO (Single Input
Single Output/Multiple Input Single Output) encoder 119.
[0086] The SISO/MISO encoder 119 applies time-space
encoding to the data from the time interleaver 118 to
supply to a frequency interleaver 120.
[0087] The frequency interleaver 120 performs
frequency interleave (interleave in a frequency
direction) for the unit of the data from the SISO/MISO
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encoder 119 in a symbol unit, and supplies it to a frame
builder & resource allocation 131.
[0088] On the other hand, control data for
transmission control (signaling) such as Base Band
Signaling, BB Header and the like is supplied to the BCH
encoder 121, for example.
[0089] The BCH encoder 121 performs the BCH encoding
of the control data supplied thereto in the same manner
as the BCH encoder 114 and supplies the data obtained as
a result to an LDPC encoder 122.
[0090] The LDPC encoder 122 performs the LDPC encoding
of the data from the BCH encoder 121 as the LDPC target
data in the same manner as the LDPC encoder 115 and
supplies the LDPC code obtained as a result to a mapper
123.
[0091] The mapper 123 maps the LDPC code from the LDPC
encoder 122 onto the signal point indicating one symbol
of the orthogonal modulation in units of one or more code
bits of the LDPC code (symbol unit) to perform the
orthogonal modulation and supplies the data obtained as a
result to a frequency interleaver 124 in the same manner
as the mapper 117.
[0092] The frequency interleaver 124 performs the
frequency interleave of the data from the mapper 123 in a
symbol unit to supply to the frame builder & resource
allocation 131 in the same manner as the frequency
interleaver 120.
[0093] The frame builder & resource allocation 131
CA 02924874 2016-03-18
inserts a pilot symbol into a required position of the
data (symbol) from the frequency interleavers 120 and 124
and constitutes a frame configured of a predetermined
number of symbols (for example, a PL (Physical Layer)
5 frame, a T2 frame, a C2 frame and the like) from the data
(symbol) obtained as a result to supply to an OFDM
generation 132.
[0094] The OFDM generation 132 generates an OFDM
signal corresponding to the frame from the frame from the
10 frame builder & resource allocation 131 and transmits the
same through the communication channel 13 (Fig. 7).
[0095] The transmitting device 11 may be configured
without including some of the blocks shown in Fig. 8,
e.g., the time interleaver 118, the SISO/MISO encoder 119,
15 the frequency interleaver 120, and frequency interleaver
124.
[0096]
<Configuration example of bit interleaver 116>
[0097] Fig. 9 is block diagram showing a configuration
20 example of the bit interleaver 116 in Fig. 8.
[0098] The bit interleaver 116 has a function to
interleave the data, and is configured of a parity
interleaver 23, a group-wise interleaver 24, and a block
interleaver 25.
25 [0099] The parity interleaver 23 performs parity
interleave to interleave the parity bit of the LDPC code
from the LDPC encoder 115 to a position of another parity
bit and supplies the LDPC code after the parity
CA 02924874 2016-03-18
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interleave to the group-wise interleaver 24.
[0100] The group-wise interleaver 24 performs group-
wise interleave of the LDPC code from the parity
interleaver 23 and supplies the LDPC code after the
group-wise interleave to the block interleaver 25.
[0101] Here, in the group-wise interleave, the LDPC
code for one code is divided into a 360-bit unit equal to
the number of columns P being the unit of the cyclic
structure as described later from the beginning. One
division, i.e., 360-bit, is considered as a bit group.
The LDPC code from the parity interleaver 23 is
interleaved in a bit group unit.
[0102] When the group-wise interleave is performed,
the bit error rate can be improved as compared with the
case that no group-wise interleave is performed. As a
result, in the data transmission, it is possible to
ensure good communication quality.
[0103] The block interleaver 25 performs the block
interleave for demultiplexing the LDPC code from the
group-wise interleaver 24, symbolizes the LDPC code for
one code into the m bit symbol in a mapping unit, and
supplies it to the mapper 117 (Fig. 8).
[0104] Here, there is a storage region where columns
for storing a predetermined number of bits in a column
(vertical) direction are arranged in equal numbers to the
bit numbers m of the symbol in a row (horizontal)
direction. In the block interleave, the LDPC code from
the group-wise interlever 24 is written in the column
CA 02924874 2016-03-18
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direction and read in the row direction, thereby
symbolizing the LDPC code for one code into the m bit
symbol.
[0105]
<Parity check matrix of LDPC code>
[0106] Fig. 10 shows the parity check matrix H used by
the LDPC encoder 115 in Fig. 8.
[0107] The parity check matrix H has an LDGM (low-
density generation matrix) structure and this may be
represented by an equation H = [HAIHT] (a matrix in which
a left element is an element of an information matrix HA
and a right element is an element of a parity matrix HT)
by the information matrix HA of a part corresponding to
the information bit and the parity matrix HT corresponding
to the parity bit out of the code bits of the LDPC code.
[0108] Herein, the number of information bits and the
number of parity bits out of the code bits of one LDPC
code (one code word) are referred to as an information
length K and a parity length M, respectively, and the
number of code bits of one LDPC code is referred to as a
code length N (= K + M).
[0109] The information length K and the parity length
M of the LDPC code of a certain code length N are
determined according to the code rate. The parity check
matrix H is an M x N (row x column) matrix. The
information matrix HA is an M x K matrix and the parity
matrix HT is an M x M matrix.
[0110] Fig. 11 is a drawing showing an example of the
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parity matrix HT of the parity check matrix H used for the
LDPC encoding by the LDPC encoder 115 in Fig. 8.
[0111] The parity matrix HT of the parity check matrix
H used for the LDPC encoding by the LDPC encoder 115 is
similar to the parity matrix HT of the parity check matrix
H of the LDPC code specified in the DVB-T.2 standard.
[0112] The parity matrix HT of the parity check matrix
H of the LDPC code specified in the DVB-T.2 standard has
a lower bidiagonal matrix in which elements of 1 are
arranged in a so-called stepwise manner as shown in Fig.
11. A row weight of the parity matrix HT is 1 for a first
row and 2 for all other rows. A column weight is 1 for a
last column and 2 for all other columns.
[0113] As described above, the LDPC code of the parity
check matrix H in which the parity matrix HT has the
stepwise structure may be easily generated using the
parity check matrix H.
[0114] That is to say, the LDPC code (one code word)
is represented by a row vector c and a column vector
obtained by transposing the row vector is represented as
cT. A part of the information bit of the row vector c,
which is the LDPC code, is represented by a row vector A
and a part of the parity bit is represented by a row
vector T.
[0115] In this case, the row vector c may be
represented by an equation c = [AIT] (row vector in which
a left element is an element of the row vector A and a
right element is an element of the row vector T) by the
CA 02924874 2016-03-18
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row vector A as the information bit and the row vector T
as the parity bit.
[0116] The parity check matrix H and the row vector c
= [AIT] as the LDPC code are required to satisfy an
equation HcT = 0 and it is possible to sequentially obtain
(in order) the row vector T as the parity bit configuring
the row vector c = [AIT] satisfying such equation HcT = 0
by setting the element of each row to 0 in order from the
element of a first row of the column vector HcT in the
equation HcT = 0 when the parity matrix HT of the parity
check matrix H = [HAIHT] has the stepwise structure
illustrated in Fig. 11.
[0117] Fig. 12 is a view illustrating the parity check
matrix H of the LDPC code specified in the DVB-T.2
standard.
[0118] The column weight is X for first to KX-th
columns, the column weight is 3 for next K3 columns, the
column weight is 2 for next M-1 columns, and the column
weight is 1 for a last column in the parity check matrix
H of the LDPC code specified in the DVB-T.2 standard.
[0119] Herein, KX + K3 + M - 1 + 1 equals to the code
length N.
[0120] Fig. 13 is a view showing the numbers of
columns KX, K3, and M and the column weight X for each
code rate r of the LDPC code specified in the DVB-T.2
standard.
[0121] The LDPC codes whose code lengths N are 64800
bits and 16200 bits are specified in the DVB-T.2 standard.
CA 02924874 2016-03-18
[0122] For the LDPC code whose code length N is 64800
bits, 11 code rates (nominal rates) 1/4, 1/3, 2/5, 1/2,
3/5, 2/3, 3/4, 4/5, 5/6, 8/9, and 9/10 are specified, and
for the LDPC code whose code length N is 16200 bits, 10
5 code rates 1/4, 1/3, 2/5, 1/2, 3/5, 2/3, 3/4, 4/5, 5/6,
and 8/9 are specified.
[0123] The code length N of 64800 bits is hereinafter
also referred to as 64k bits and the code length of 16200
bits is also referred to as 16k bits.
10 [0124] As for the LDPC code, it is known that a bit
error rate of the code bit corresponding to the column
whose column weight is larger of the parity check matrix
H is lower.
[0125] In the parity check matrix H specified in the
15 DVB-T.2 standard illustrated in Figs. 12 and 13, the
column weight of the column closer to a top (leftmost)
column tends to be larger, therefore, as for the LDPC
code corresponding to the parity check matrix H, the code
bit closer to a top code bit closer to a top code bit
20 tends to be more tolerant to error (resistant to error)
and the code bit closer to a last code bit tends to be
less tolerant to error.
[0126]
<Parity interleave>
25 [0127] Referring to Fig. 14 to Fig. 16, the parity
interleave by the parity interleaver 23 in Fig. 9 is
described.
[0128] Fig. 14 shows (a part of) a Tanner graph of the
CA 02924874 2016-03-18
41
parity check matrix of the LDPC code.
[0129] The check node returns the message indicating
that the probability that the value is 0 and the
probability that the value is 1 are equal to all the
variable nodes connected to the check node when the error
such as the erasure occurs in a plurality (for example,
two) of (code bits corresponding to the) variable nodes
connected to the check node at the same time as
illustrated in Fig. 14. Therefore, when the erasure and
the like occur at the same time in a plurality of
variable nodes connected to the same check node, the
decoding performance is deteriorated.
[0130] The LDPC code specified in the DVB-S.2 standard
output by the LDPC encoder 115 in Fig. 8 is the IRA code
and the parity matrix HT of the parity check matrix H has
the stepwise structure as illustrated in Fig. 11.
[0131] Fig. 15 shows the parity matrix HT having the
stepwise structure and the Tanner graph corresponding to
the parity matrix HT, as shown in Fig. 11.
[0132] Fig. 15A shows the parity matrix HT having the
stepwise structure and Fig. 15B shows the Tanner graph
corresponding to the parity matrix HT in Fig. 15A.
[0133] In the parity matrix HT having the stepwise
structure, the elements of 1 are adjacent to each other
in each row (except the first row). Therefore, in the
Tanner graph of the parity matrix HT, two adjacent
variable nodes corresponding to the columns of the two
adjacent elements whose value is 1 of the parity matrix HT
CA 02924874 2016-03-18
42
are connected to the same check node.
[0134] Therefore, when the error occurs in the parity
bits corresponding to the above-described adjacent two
variable nodes at the same time due to the burst error,
the erasure and the like, the check node connected to the
two variable nodes (the variable nodes, which obtain the
message using the parity bits) corresponding to the two
parity bits in which the error occurs returns the message
indicating that the probability that the value is 0 and
the probability that the value is 1 are equal to the
variable nodes connected to the check node, whereby the
decoding performance is deteriorated. When a burst length
(the number of parity bits in which the error is
successively occurs) increases, the number of check nodes,
which return the message of the equal probability,
increases and the decoding performance is further
deteriorated.
[0135] Then, the parity interleaver 23 (Fig. 9)
performs the parity interleave to interleave the parity
bit of the LDPC code from the LDPC encoder 115 to the
position of another parity bit in order to prevent the
above-described deterioration in decoding performance.
[0136] Fig. 16 shows the parity matrix HT of the parity
check matrix H corresponding to the LDPC code after the
parity interleave performed by the parity interleaver 23
in Fig. 9.
[0137] Herein, the information matrix HA of the parity
check matrix H corresponding to the LDPC code output by
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the LDPC encoder 115 has a cyclic structure, similar to
the information matrix of the parity check matrix H
corresponding to the LDPC code specified in the DVB-T.2
standard.
[0138] The term "cyclic structure" is intended to mean
a structure in which a certain column is identical to a
column obtained by a cyclic shift of another column and
includes a structure in which a position of 1 in each row
of P columns is set to a position obtained by the cyclic
shift of a first column of the P columns in the column
direction by a value proportional to a value q obtained
by dividing the parity length M for each P columns, for
example. Hereinafter, P in the cyclic structure is
appropriately referred to as the number of columns being
a unit of the cyclic structure.
[0139] There are two types of LDPC codes whose code
lengths N are 64800 bits and 16200 bits as the LDPC code
specified in the DVB-T.2 standard as illustrated in Figs.
12 and 13, and the number of columns P being the unit of
the cyclic structure is set to 360, which is one of
submultiples other than 1 and M out of the submultiples
of the parity length M for both of the two LDPC codes.
[0140] The parity length M is set to a value other
thanaprime number represented by an equationM=qxP
= q x 360 using the value q different according to the
code rate. Therefore, as the number of columns P being
the unit of the cyclic structure, the value q also is
another submultiple other than 1 and M out of the
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submultiples of the parity length M and this may be
obtained by dividing the parity length M by the number of
columns P being the unit of the cyclic structure (a
product of P and q being the submultiples of the parity
length M is the parity length M).
[0141] When the information length is K, an integer
not smaller than 0 and smaller than P is x, and an
integer not smaller than 0 and smaller than q is y, the
parity interleaver 23 interleaves a K + qx + y + 1-th
code bit out of the code bits of the N-bit LDPC code to a
position of a K + Py + x + 1-th code bit as the parity
interleave as described above.
[0142] Both the K + qx + y + 1-th code bit and the K +
Py + x + 1-th code bit are the code bits after a K + 1-th
code bit, so that they are the parity bits, therefore,
the position of the parity bit of the LDPC code is moved
by the parity interleave.
[0143] According to such parity interleave, (the
parity bits corresponding to) the variable nodes
connected to the same check node are apart from each
other by the number of columns P being the unit of the
cyclic structure, that is to say, herein 360 bits, so
that a situation in which the error occurs in a plurality
of variable nodes connected to the same check node at the
same time may be avoided in a case in which the burst
length is shorter than 360 bits, and as a result, the
resistance to burst error may be improved.
[0144] The LDPC code after the parity interleave to
CA 02924874 2016-03-18
interleave the K + qx + y + 1-th code bit to the position
of the K + Py + x + 1-th code bit is identical to the
LDPC code of the parity check matrix obtained by
performing column permutation to change the K + qx + y +
5 1-th column of the original parity check matrix H to the
K + qx + x + 1-th column (hereinafter, also referred to
as a conversion parity check matrix).
[0145] Also, a quasi-cyclic structure in units of P
columns (360 columns in Fig. 16) appears in the parity
10 matrix of the conversion parity check matrix as
illustrated in Fig. 16.
[0146] Herein, the term "quasi-cyclic structure" is
intended to mean a structure in which a portion except a
part has the cyclic structure.
15 [0147] In the conversion parity check matrix obtained
by applying the column permutation corresponding to the
parity interleave to the parity check matrix of the LDPC
code specified in the DVB-T.2 standard, one element 1 is
lacking (there is an element 0) in a portion of 360 rows
20 x 360 columns in a right corner of the conversion parity
check matrix (a shift matrix to be described later), so
that this does not have the (complete) cyclic structure
and has the so-called quasi-cyclic structure in this
point.
25 [0148] The conversion parity check matrix of the
parity check matrix of the LDPC code output by the LDPC
encoder 115 has a quasi-cyclic structure, similar to the
conversion parity check matrix of the parity check matrix
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H of the LDPC code specified in the DVB-T.2 standard.
[0149] The conversion parity check matrix in Fig. 16
is the matrix obtained by applying permutation of the row
(row permutation) for allowing the conversion parity
check matrix to be configured of a constitutive matrix to
be described later to the original parity check matrix H
in addition to the column permutation corresponding to
the parity interleave.
[0150] Fig. 17 is a flowchart for explaining the
processing performed by the LDPC encoder 115, the bit
interleaver 116 and the mapper 117 in Fig. 8.
[0151] The LDPC encoder 115 encodes the LDPC target
data into the LDPC code at step S101 after waiting for
supply of the LDPC target data from the BCH encoder 114
and supplies the LDPC code to the bit interleaver 116,
then the process shifts to step S102.
[0152] The bit interleaver 116 performs the bit
interleave of the LDPC code from the LDPC encoder 115 and
supplies the symbol obtained by the bit interleave to the
mapper 117 at step S102, then the process shifts to step
S103.
[0153] That is to say, at step S102, in the bit
interleaver 116 (Fig. 9), the parity interleaver 23
performs the parity interleave of the LDPC code from the
LDPC encoder 115 and supplies the LDPC code after the
parity interleave to the group-wise interleaver 24.
[0154] The group-wise interleaver 24 performs the
group-wise interleave of the LDPC code from the parity
CA 02924874 2016-03-18
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interleaver 23 to supply to the block interleaver 25.
[0155] The block interleaver 25 performs the block
interleave of the LDPC code after the group-wise
interleave by the group-wise interleaver 24 and supplies
the m bit symbol obtained as a result to the mapper 117.
[0156] The mapper 117 maps the symbol from the block
interleaver 25 onto any of the 2m signal points defined
by the modulation scheme of the orthogonal modulation
performed by the mapper 117 to perform the orthogonal
modulation and supplies the data obtained as a result to
the time interleaver 118 at step S103.
[0157] As described above, it is possible to improve
the error rate in a case in which a plurality of code
bits of the LDPC code is transmitted as one symbol by
performing the parity interleave and the group-wise
interleave.
[0158] Herein, the parity interleaver 23, which is a
block to perform the parity interleave, and the group-
wise interleaver 24, which is a block to perform the
group-wise interleave, are separately formed in Fig. 9
for convenience of description; however, the parity
interleaver 23 and the group-wise interleaver 24 may be
integrally formed.
[0159] That is to say, the parity interleave and the
group-wise interleave may be performed by the writing and
the reading of the code bit to and from the memory and
may be represented by a matrix to convert the address at
which the code bit is written (write address) to the
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address at which the code bit is read (read address).
[0160] Therefore, by obtaining the matrix obtained by
multiplying the matrix representing the parity interleave
by the matrix representing the group-wise interleave, it
is possible to obtain a result of performing the parity
interleave and performing the group-wise interleave of
the LDPC code after the parity interleave by converting
the code bit by the matrix.
[0161] It is also possible to integrally form the
block interleaver 25 in addition to the parity
interleaver 23 and the group-wise interleaver 24.
[0162] That is to say, the block interleave performed
by the block interleaver 25 may also be represented by
the matrix to convert the write address of the memory,
which stores the LDPC code, to the read address.
[0163] Therefore, by obtaining the matrix obtained by
multiplying the matrix representing the parity interleave,
the matrix representing the group-wise interleave, and
the matrix representing the block interleave together, it
is possible to collectively perform the parity interleave,
the group-wise interleave, and the block interleave by
the matrix.
[0164]
<Configuration example of LDPC encoder 115>
[0165] Fig. 18 is a block diagram illustrating a
configuration example of the LDPC encoder 115 in Fig. 8.
[0166] The LDPC encoder 122 in Fig. 8 also is
configured in the same manner.
CA 02924874 2016-03-18
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[0167] As illustrated in Figs. 12 and 13, the LDPC
codes of the two code lengths N of 64800 bits and 16200
bits are specified in the DVB-S.2 standard.
[0168] As for the LDPC code whose code length N is
64800 bits, 11 code rates 1/4, 1/3, 2/5, 1/2, 3/5, 2/3,
3/4, 4/5, 5/6, 8/9, and 9/10 are specified, and as for
the LDPC code whose code length N is 16200 bits, 10 code
rates 1/4, 1/3, 2/5, 1/2, 3/5, 2/3, 3/4, 4/5, 5/6 and 8/9
are specified (refer to Figs. 12 and 13).
[0169] The LDPC encoder 115 may perform the encoding
(error correction encoding) by such LDPC code of each
code rate whose code lengths N are 64800 bits or 16200
bits according to the parity check matrix H prepared for
each code length N and each code rate, for example.
[0170] The LDPC encoder 115 is configured of an
encoding processor 601 and a storage unit 602.
[0171] The encoding processor 601 is configured of a
code rate set unit 611, an initial value table read unit
612, a parity check matrix generation unit 613, an
information bit read unit 614, an encoding parity
operation unit 615, and a controller 616, and this
performs the LDPC encoding of the LDPC target data
supplied to the LDPC encoder 115 and supplies the LDPC
code obtained as a result to the bit interleaver 116 (Fig.
8).
[0172] That is to say, the code rate set unit 611 sets
the code length N and the code rate of the LDPC code
according to the operation of the operator and the like,
CA 02924874 2016-03-18
for example.
[0173] The initial value table read unit 612 reads a
parity check matrix initial value table to be described
later corresponding to the code length N and the code
5 rate set by the code rate set unit 611 from the storage
unit 602.
[0174] The parity check matrix generation unit 613
generates the parity check matrix H by arranging the
element 1 of the information matrix HA corresponding to
10 the information length K (= code length N - parity length
M) according to the code length N and the code rate set
by the code rate set unit 611 with a period of 360
columns (the number of columns P being the unit of the
cyclic structure) in the column direction based on the
15 parity check matrix initial value table read by the
initial value table read unit 612 and stores the same in
the storage unit 602.
[0175] The information bit read unit 614 reads
(extracts) the information bits as many as the
20 information length K from the LDPC target data supplied
to the LDPC encoder 115.
[0176] The encoding parity operation unit 615 reads
the parity check matrix H generated by the parity check
matrix generation unit 613 from the storage unit 602 and
25 calculates the parity bit for the information bit read by
the information bit read unit 614 based on a
predetermined equation using the parity check matrix H,
thereby generating the code word (LDPC code).
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[0177] The controller 616 controls each block
configuring the encoding processor 601.
[0178] A plurality of parity check matrix initial
value tables and the like corresponding to a plurality of
code rates and the like illustrated in Figs. 12 and 13
for each of the code lengths N such as 64800 bits and
16200 bits is stored in the storage unit 602, for example.
The storage unit 602 temporarily stores the data required
in the process of the encoding processor 601.
[0179] Fig. 19 is a flowchart illustrating the process
of the LDPC encoder 115 in Fig. 18.
[0180] At step S201, the code rate set unit 611
determines (sets) the code length N and the code rate r
with which the LDPC encoding is performed.
[0181] At step S202, the initial value table read unit
612 reads the parity check matrix initial value table
determined in advance corresponding to the code length N
and the code rate r determined by the code rate set unit
611 from the storage unit 602.
[0182] At step S203, the parity check matrix
generation unit 613 obtains (generates) the parity check
matrix H of the LDPC code whose code length N and the
code rate r determined by the code rate set unit 611
using the parity check matrix initial value table read by
the initial value table read unit 612 from the storage
unit 602 and supplies the same to the storage unit 602 to
store.
[0183] At step S204, the information bit read unit 614
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reads the information bits of the information length K (=
N x r) corresponding to the code length N and the code
rate r determined by the code rate set unit 611 from the
LDPC target data supplied to the LDPC encoder 115 and
reads the parity check matrix H obtained by the parity
check matrix generation unit 613 from the storage unit
602 to supply to the encoding parity operation unit 615.
[0184] At step S205, the encoding parity operation
unit 615 sequentially calculates the parity bit of the
code word c satisfying equation (8) using the information
bit from the information bit read unit 614 and the parity
check matrix H.
[0185]
HoT = 0 ... (8)
[0186] In equation (8), c represents the row vector as
the code word (LDPC code) and CT represents transposition
of the row vector c.
[0187] Herein, as described above, when the part of
the information bit and the part of the parity bit of the
row vector c as the LDPC code (one code word) are
represented by the row vector A and the row vector T,
respectively, the row vector c may be represented by the
equation c = [AIT] by the row vector A as the information
bit and the row vector T as the parity bit.
[0188] The parity check matrix H and the row vector c
[AIT] as the LDPC code are required to satisfy the
equation HcT = 0 and it is possible to sequentially obtain
the row vector T as the parity bit configuring the row
CA 02924874 2016-03-18
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vector c = [AIT] satisfying such equation HcT = 0 by
setting the element of each row to 0 in order from the
element of the first row of the column vector HcT in the
equation HcT = 0 when the parity matrix HT of the parity
check matrix H = [HAIHT] has the stepwise structure
illustrated in Fig. 11.
[0189] When the encoding parity operation unit 615
obtains the parity bit T for the information bit A from
the information bit read unit, this outputs the code word
c ¨ [AIT] represented by the information bit A and the
parity bit T as a result of the LDPC encoding of the
information bit A.
[0190] Thereafter, at step S206, the controller 616
judges whether to finish the LDPC encoding. At step S206,
when it is judged that the LDPC encoding is not finished,
that is to say, when there still is the LDPC target data
to be LDPC encoded, for example, the process returns to
step S201 (or step S204) and the processes at steps S201
(or step S204) to S206 are hereinafter repeated.
[0191] When it is judged that the LDPC encoding is
finished at step S206, that is to say, there is no LDPC
target data to be LDPC encoded, for example, the LDPC
encoder 115 finishes the process.
[0192] In this manner, the parity check matrix initial
value table corresponding to each code length N and each
code rate r is prepared, and the LDPC encoder 115
performs the LDPC encoding with a predetermined code
length N and a predetermined code rate r using the parity
CA 02924874 2016-03-18
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check matrix H generated from the parity check matrix
initial value table corresponding to the predetermined
code length N and the predetermined code rate r.
[0193]
<Example of parity check matrix initial value table>
[0194] The parity check matrix initial value table is
the table indicating the position of the element 1 of the
information matrix HA (Fig. 10) corresponding to the
information length K according to the code length N and
code rate r is the LDPC code (LDPC code defined by the
parity check matrix H) of the parity check matrix for
each 360 columns (the number of columns P being the unit
of the cyclic structure) and is created in advance for
each parity check matrix H of each code length N and each
code rate r.
[0195] Fig. 20 is a view illustrating an example of
the parity check matrix initial value table.
[0196] That is to say, Fig. 20 illustrates the parity
check matrix initial value table for the parity check
matrix H whose code length N is 16200 bits and code rate
(code rate in notation of DVB-T.2) r is 1/4 specified in
the DVB.T-2 standard.
[0197] The parity check matrix generation unit 613
(Fig. 18) obtains the parity check matrix H in a
following manner using the parity check matrix initial
value table.
[0198] Fig. 21 illustrates a method of obtaining the
parity check matrix H from the parity check matrix
CA 02924874 2016-03-18
initial value table.
[0199] In other words, the parity check matrix initial
value table in Fig. 21 illustrates the parity check
matrix initial value table for the parity check matrix H
5 whose code length N is 16200 bits and code rate r is 2/3
specified in the DVB.T-2 standard.
[0200] The parity check matrix initial value table is
the table indicating the position of the element 1 of the
information matrix HA (Fig. 10) corresponding to the
10 information length K according to the code length N and
code rate r is the LDPC code for each 360 columns (the
number of columns P being the unit of the cyclic
structure) as described above in which row numbers (the
row number of the first row of the parity check matrix H
15 is 0) of the elements of 1 of a 1 + 360 x (i - 1)-th
column of the parity check matrix H as many as the number
of column weights of the 1 + 360 x (i - 1)-th column are
arranged in an i-th row.
[0201] Herein, the parity matrix HT (Fig. 10)
20 corresponding to the parity length M of the parity check
matrix H is determined as illustrated in Fig. 15, so that
the information matrix HA (Fig. 10) corresponding to the
information length K of the parity check matrix H is
obtained according to the parity check matrix initial
25 value table.
[0202] The number of rows k + 1 of the parity check
matrix initial value table differs according to the
information length K.
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[0203] The information length K and the number of rows
k + 1 of the parity check matrix initial value table
satisfy relationship in equation (9).
[0204]
K = (k+1) x 360 .... (9)
[0205] Herein, 360 in equation (9) is the number of
columns P being the unit of the cyclic structure
illustrated in Fig. 16.
[0206] In the parity check matrix initial value table
in Fig. 21, 13 values are arranged in each of first to
third rows and 3 values are arranged in each of fourth to
k + 1-th rows (30th row in Fig. 21).
[0207] Therefore, the column weights of the parity
check matrix H obtained from the parity check matrix
initial value table in Fig. 21 are 13 from the first
column to 1 + 360 x (3 - 1) -1-th column and 3 from the 1
+ 360 x (3 - 1)-th column to a K-th column.
[0208] The first row of the parity check matrix
initial value table in Fig. 21 is 0, 2084, 1613, 1548,
1286, 1460, 3196, 4297, 2481, 3369, 3451, 4620, and 2622
and this indicates that the element of the rows whose row
numbers are 0, 2084, 1613, 1548, 1286, 1460, 3196, 4297,
2481, 3369, 3451, 4620, and 2622 is 1 (and other elements
are 0) in the first column of the parity check matrix H.
[0209] Also, the second row of the parity check matrix
initial value table in Fig. 21 is 1, 122, 1516, 3448,
2880, 1407, 1847, 3799, 3529, 373, 971, 4358, and 3108
and this indicates that the element of the rows whose row
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numbers are 1, 122, 1516, 3448, 2880, 1407, 1847, 3799,
3529, 373, 971, 4358, and 3108 are 1 in a 361 (= 1 + 360
x (2 - 1))-th column of the parity check matrix H.
[0210] As described above, the parity check matrix
initial value table indicates the position of the element
1 of the information matrix HA of the parity check matrix
H for each 360 columns.
[0211] The column other than the 1 + 360 x (i - 1)-th
column of the parity check matrix H, that is to say, each
column from a 2 + 360 x (i - 1)-th column to a 360 x i-th
column is obtained by periodically performing the cyclic
shift to the element 1 of the 1 + 360 x (i - 1)-th column
determined by the parity check matrix initial value table
downward (in a direction toward a lower part of the
column) according to the parity length M to arrange.
[0212] That is to say, the 2 + 360 x (i - 1)-th column
is obtained by the cyclic shift of the 1 + 360 x (i - 1)-
th column downward by M/360 (= q) and a next 3 + 360 x (i
- 1)-th column is obtained by the cyclic shift of the 1 +
360 x (i - 1)-th column downward by 2 x M/360 (= 2 x q)
(the cyclic shift of the 2 + 360 x (i - 1)-th column
downward by M/360(= q)), for example.
[0213] Herein, if an i-th row (i-th row from the top)
j-th column (j-th column from left) value of the parity
check matrix initial value table is represented as hi, j
and the row number of a j-th element 1 of a w-th column
of the parity check matrix H is represented as Hw-j, a row
number Hw_j of the element 1 of the w-th column being the
CA 02924874 2016-03-18
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column other than the 1 + 360 x (i - 1)-th column of the
parity check matrix H may be obtained by equation (10).
[0214]
Hw-i = mod{hi, j-Fmod((w-l), P) x q, M) (10)
[0215] Herein, mod (x, y) represents a remainder
obtained when x is divided by y.
[0216] Also, P represents the above-described number
of columns being the unit of the cyclic structure, which
is set to 360 as described above in the DVB-S.2 standard,
the DVB-T.2 standard and the DVB-C.2 standard, for
example. Further, q represents a value M/360 obtained by
dividing the parity length M by the number of columns P
(= 360) being the unit of the cyclic structure.
[0217] The parity check matrix generation unit 613
(Fig. 18) specifies the row number of the element 1 of
the 1 + 360 x (i - 1)-th column of the parity check
matrix by the parity check matrix initial value table.
[0218] Further, the parity check matrix generation
unit 613 (Fig. 18) obtains the row number of the
element 1 of the w-th column being the column other than
the 1 + 360 x (i - 1)-th column of the parity check
matrix H according to equation (10) and generates the
parity check matrix H in which an element of the row
number obtained from above is 1.
[0219]
<New LDPC code>
[0220]
At present, the standard for terrestrial digital
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television broadcasting which is called as ATSC3.0 is
planned.
[0221] A planned LDPC code (hereinafter also referred
to as a "new LDPC code") such as ATSC3.0 and other data
broadcasting will be described.
[0222] As for the new LDPC code, the parity matrix HT
of the parity check matrix H has the stepwise structure
(Fig. 11) as is the case with the LDPC code specified in
DVB-T.2 from a viewpoint of maintaining compatibility
with DVB-T.2 as far as possible.
[0223] Further, as for the new LDPC code, as is the
case with the LDPC code specified in DVB-T.2, the
information matrix HA of the parity check matrix H has the
cyclic structure and the number of columns P being the
unit of the cyclic structure is set to 360.
[0224] The LDPC encoder 115 (Fig. 8, Fig. 18) performs
the LDPC encoding to the new LDPC encoding using the
parity check matrix H obtained from the parity check
matrix initial value table of the new LDPC encoding whose
code length N is 16k bits or 64k bits and any of the code
rates r of 6/15, 7/15, 8/15, 9/15, 10/15, 11/15, 12/15 or
13/15 as described below.
[0225] In this case, the parity check matrix initial
value table is stored in the storage unit 602 of the LDPC
encoder 115 (Fig. 8).
[0226] Fig. 22, Fig. 23 and Fig. 24 each is a diagram
showing the parity check matrix initial value table of
the parity check matrix H of a first new LDPC code whose
CA 02924874 2016-03-18
code length N is 64k bits and code rate r is 7/15
(hereinafter also referred to as a "first new LDPC code
of (64k, 7/15)).
[0227] Fig. 23 follows Fig. 22. Fig. 24 follows Fig.
5 23.
[0228] Fig. 25, Fig. 26 and Fig. 27 each is a diagram
showing the parity check matrix initial value table of
the parity check matrix H of a first new LDPC code whose
code length N is 64k bits and code rate r is 9/15
10 (hereinafter also referred to as a "first new LDPC code
of (64k, 9/15)).
[0229] Fig. 26 follows Fig. 25. Fig. 27 follows Fig.
26.
[0230] Fig. 28, Fig. 29 and Fig. 30 each is a diagram
15 showing the parity check matrix initial value table of
the parity check matrix H of a first new LDPC code whose
code length N is 64k bits and code rate r is 11/15
(hereinafter also referred to as a "first new LDPC code
of (64k, 11/15)).
20 [0231] Fig. 29 follows Fig. 28. Fig. 30 follows Fig.
29.
[0232] Fig. 31, Fig. 32 and Fig. 33 each is a diagram
showing the parity check matrix initial value table of
the parity check matrix H of a first new LDPC code whose
25 code length N is 64k bits and code rate r is 13/15
(hereinafter also referred to as a "first new LDPC code
of (64k, 13/15)).
[0233] Fig. 32 follows Fig. 31. Fig. 33 follows Fig.
CA 02924874 2016-03-18
61
32.
[0234] Fig. 34 is a diagram showing the parity check
matrix initial value table of the parity check matrix H
of a first new LDPC code whose code length N is 16k bits
and code rate r is 6/15 (hereinafter also referred to as
a "first new LDPC code of (16k, 6/15)).
[0235] Fig. 35 is a diagram showing the parity check
matrix initial value table of the parity check matrix H
of a first new LDPC code whose code length N is 16k bits
and code rate r is 8/15 (hereinafter also referred to as
a "first new LDPC code of (16k, 8/15)).
[0236] Fig. 36 is a diagram showing the parity check
matrix initial value table of the parity check matrix H
of a first new LDPC code whose code length N is 16k bits
and code rate r is 10/15 (hereinafter also referred to as
a "first new LDPC code of (16k, 10/15)).
[0237] Fig. 37 is a diagram showing the parity check
matrix initial value table of the parity check matrix H
of a first new LDPC code whose code length N is 16k bits
and code rate r is 12/15 (hereinafter also referred to as
a "first new LDPC code of (16k, 12/15)).
[0238] Fig. 38 is a diagram showing the parity check
matrix initial value table of the parity check matrix H
of a first other new LDPC code whose code length N is 16k
bits and code rate r is 10/15 (hereinafter also referred
to as a "first other new LDPC code of (16k, 10/15)).
[0239] Fig. 39 is a diagram showing the parity check
matrix initial value table of the parity check matrix H
CA 02924874 2016-03-18
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of a first other new LDPC code whose code length N is 16k
bits and code rate r is 12/15 (hereinafter also referred
to as a "first other new LDPC code of (16k, 12/15)).
[0240] Fig. 40 and Fig. 41 each is a diagram showing
the parity check matrix initial value table of the parity
check matrix H of a second new LDPC code whose code
length N is 64k bits and code rate r is 6/15 (hereinafter
also referred to as a "second new LDPC code of (64k,
6/15)).
[0241] Fig. 41 follows Fig. 40.
[0242] Fig. 42, Fig. 43 and Fig. 44 each is a diagram
showing the parity check matrix initial value table of
the parity check matrix H of a second new LDPC code whose
code length N is 64k bits and code rate r is 8/15
(hereinafter also referred to as a "second new LDPC code
of (64k, 8/15)).
[0243] Fig. 43 follows Fig. 42. Fig. 44 follows Fig.
43.
[0244] Fig. 45, Fig. 46 and Fig. 47 each is a diagram
showing the parity check matrix initial value table of
the parity check matrix H of a second new LDPC code whose
code length N is 64k bits and code rate r is 10/15
(hereinafter also referred to as a "second new LDPC code
of (64k, 10/15))=
[0245] Fig. 46 follows Fig. 45. Fig. 47 follows Fig.
46.
[0246] Fig. 48, Fig. 49 and Fig. 50 each is a diagram
showing the parity check matrix initial value table of
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the parity check matrix H of a second new LDPC code whose
code length N is 64k bits and code rate r is 12/15
(hereinafter also referred to as a "second new LDPC code
of (64k, 12/15)).
[0247] Fig. 49 follows Fig. 48. Fig. 50 follows Fig.
49.
[0248] Fig. 51 is a diagram showing the parity check
matrix initial value table of the parity check matrix H
of a second new LDPC code whose code length N is 16k bits
and code rate r is 7/15 (hereinafter also referred to as
a "second new LDPC code of (16k, 7/15)).
[0249] Fig. 52 is a diagram showing the parity check
matrix initial value table of the parity check matrix H
of a second new LDPC code whose code length N is 16k bits
and code rate r is 9/15 (hereinafter also referred to as
a "second new LDPC code of (16k, 9/15)).
[0250] Fig. 53 is a diagram showing the parity check
matrix initial value table of the parity check matrix H
of a second new LDPC code whose code length N is 16k bits
and code rate r is 11/15 (hereinafter also referred to as
a "second new LDPC code of (16k, 11/15)).
[0251] Fig. 54 is a diagram showing the parity check
matrix initial value table of the parity check matrix H
of a second new LDPC code whose code length N is 16k bits
and code rate r is 13/15 (hereinafter also referred to as
a "second new LDPC code of (16k, 13/15)).
[0252] (The parity check matrix initial value tables of
the parity check matrices H of) the second new LDPC codes
CA 02924874 2016-03-18
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shown in Fig. 40 to Fig. 54 are provided from Samsung.
[0253] The first new LDPC codes and the first other new
LDPC codes are high-performance LDPC codes.
[0254] Herein, the high-performance LDPC code is obtained
from an appropriate parity check matrix H.
[0255] The term the "appropriate parity check matrix
H" is intended to mean the parity check matrix, which
satisfies a predetermined condition to make the BER (and
FER) lower when the LDPC code obtained from the parity
check matrix H is transmitted with low Es/No or Eb/No
(signal power to noise power ratio per bit).
[0256] The appropriate parity check matrix H may be
obtained by the simulation of the measurement of the BER
at the time when the LDPC code obtained from the various
parity check matrices satisfying the predetermined
condition is transmitted with the low Es/No, for example.
[0257] The predetermined condition, which the
appropriate parity check matrix H should satisfy,
includes an excellent analysis result obtained by an
analyzing method of performance of the code referred to
as density evolution, absence of a loop of the elements
of 1 referred to as cycle-4 and the like, for example.
[0258] Herein, it is known that the decoding
performance of the LDPC code is deteriorated when the
elements of 1 close up as the cycle-4 in the information
matrix HA, so that the absence of the cycle-4 is required
as the predetermined condition, which the appropriate
parity check matrix H should satisfy.
CA 02924874 2016-03-18
[0259] The predetermined condition, which the
appropriate parity check matrix H should satisfy, may be
appropriately determined from a viewpoint of improvement
in the decoding performance of the LDPC code,
5 facilitation (simplification) of the decoding process of
the LDPC code and the like.
[0260] Fig. 55 and Fig. 56 are views illustrating the
density evolution with which the analysis result as the
predetermined condition, which the appropriate parity
10 check matrix H should satisfy, is obtained.
[0261] The density evolution is the analyzing method
of the code, which calculates an expected value of the
error probability for an entire LDPC code (ensemble)
whose code length N is co characterized by a degree
15 sequence to be described later.
[0262] For example, when a variance value of noise is
set to be larger from 0 on the AWGN channel, the expected
value of the error probability of a certain ensemble,
which is initially 0, is no longer 0 when the variance
20 value of the noise becomes a certain threshold or larger.
[0263] According to the density evolution, it is
possible to determine whether performance of the ensemble
(appropriateness of the parity check matrix) is excellent
by comparing the threshold of the variance value of the
25 noise (hereinafter, also referred to as a performance
threshold) at which the expected value of the error
probability is no longer 0.
[0264] It is possible to predict rough performance of
CA 02924874 2016-03-18
66
a specific LDPC code by determining the ensemble to which
the LDPC code belongs and performing the density
evolution to the ensemble.
[0265] Therefore, when a high-performance ensemble is
found, the high-performance LDPC code may be found from
the LDPC codes belonging to the ensemble.
[0266] Herein, the above-described degree sequence
indicates a ratio of the variable node and the check node
having the weight of each value to the code length N of
the LDPC code.
[0267] For example, a regular (3, 6) LDPC code whose
code rate is 1/2 belongs to the ensemble characterized by
the degree sequence in which the weight (column weight)
of all the variable nodes is 3 and the weight (row
weight) of all the check nodes is 6.
[0268] Fig. 55 shows the Tanner graph of such ensemble.
[0269] In the Tanner graph in Fig. 55, there are N
(equal to the code length N) variable nodes represented
by a circle (0) in the drawing and N/2 (equal to a
product obtained by multiplying the code rate 1/2 by the
code length N) check nodes represented by a square (0) in
the drawing.
[0270] Three edges, the number of which is equal to
the column weight, are connected to each variable node,
so that there are a total of 3N edges connected to the N
variable nodes.
[0271] Also, six edges the number of which is equal to
the row weight, are connected to each check node, so that
CA 02924874 2016-03-18
67
there are a total of 3N edges connected to the N/2 check
nodes.
[0272] Further, there is one interleaver in the Tanner
graph in Fig. 55.
[0273] The interleaver randomly rearranges the 3N
edges connected to the N variable nodes and connects the
rearranged edges to any of the 3N edges connected to the
N/2 check nodes.
[0274] There are (3N)!(= (3N) x (3N - 1) x === x 1)
rearranging patterns of rearranging the 3N edges
connected to the N variable nodes by the interleaver.
Therefore, the ensemble characterized by the degree
sequence in which the weight of all the variable nodes is
3 and the weight of all the check nodes is 6 is a set of
(3N)! LDPC codes.
[0275] In the simulation for obtaining the high-
performance LDPC code (appropriate parity check matrix),
a multi-edge type ensemble is used in the density
evolution.
[0276] In the multi-edge type, the interleaver through
which the edge connected to the variable node and the
edge connected to the check node pass is divided into a
multi-edge one, so that the ensemble is more strictly
characterized.
[0277] Fig. 56 shows an example of the Tanner graph of
the multi-edge type ensemble.
[0278] In the Tanner graph in Fig. 56, there are two
interleavers, which are a first interleaver and a second
CA 02924874 2016-03-18
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interleaver.
[0279] In the Tanner graph in Fig. 56, there are vi
variable nodes with one edge connected to the first
interleaver and no edge connected to the second
interleaver, v2 variable nodes with one edge connected to
the first interleaver and two edges connected to the
second interleaver, and v3 variable nodes with no edge
connected to the first interleaver and two edges
connected to the second interleaver.
[0280] Further, in the Tanner graph in Fig. 56, there
are cl check nodes with two edges connected to the first
interleaver and no edge connected to the second
interleaver, c2 check nodes with two edges connected to
the first interleaver and two edges connected to the
second interleaver, and c3 check nodes with no edge
connected to the first interleaver and three edges
connected to the second interleaver.
[0281] Herein, the density evolution and
implementation thereof are described in "On the Design of
Low-Density Parity-Check Codes within 0.0045 dB of the
Shannon Limit", S. Y. Chung, G. D. Forney, T. J.
Richardson, and R. Urbanke, IEEE Communications Leggers,
VOL. 5, NO. 2, Feb 2001, for example.
[0282] In the simulation for obtaining (the parity
check matrix initial value table of) the first new LDPC
codes and the first other new LDPC code, the ensemble in
which the performance threshold being Eb/No (signal power
to noise power ratio per bit) at which the BER starts to
CA 02924874 2016-03-18
69
decrease (to be lower) is a predetermined value or
smaller is found by multi-edge type density evolution and
the LDPC code to decrease the BER is selected as the
high-performance LDPC code out of the LDPC codes
belonging to the ensemble.
[0283] The parity check matrix initial value tables of
the above-described first new LDPC codes and first other
new LDPC codes are determined by the above simulation.
[0284] Accordingly, by the first new LDPC codes and
the first other new LDPC codes obtained from the parity
check matrix initial value tables, it is possible to
ensure a good communication quality in the data
transmission.
[0285] Fig. 57 is a view showing a minimum cycle
length and a performance threshold of the parity check
matrices H obtained from the parity check matrix initial
value tables of the first new LDPC codes of (64k, 7/15),
(64k, 9/15), (64k, 11/15) and (64k, 13/15) (hereinafter
also referred to as "the parity check matrices H of the
first new LDPC codes of (64k, 7/15), (64k, 9/15), (64k,
11/15) and (64k, 13/15)) shown in Fig. 22 to Fig. 33.
[0286] Here, the minimum cycle length (girth) means a
minimum value of a length of a loop (loop length)
configured of the elements of 1 in the parity check
matrix H.
[0287] The parity check matrices H of the first new
LDPC codes of (64k, 7/15), (64k, 9/15), (64k, 11/15) and
(64k, 13/15) have no cycle-4 (the loop length of four, a
CA 02924874 2016-03-18
loop of the elements of 1).
[0288] The performance threshold of the first new LDPC
code of (64k, 7/15) is -0.093751, the performance
threshold of the first new LDPC code of (64k, 9/15) is
5 1.658523, the performance threshold of the first new LDPC
code of (64k, 11/15) is 3.351930 and the performance
threshold of the first new LDPC code of (64k, 13/15) is
5.301749.
[0289] Fig. 58 is a view illustrating the parity check
10 matrices H of the first new LDPC codes of (64k, 7/15),
(64k, 9/15), (64k, 11/15) and (64k, 13/15) in Fig. 32 to
Fig. 33.
[0290] The column weight is X1 for first to KX1-th
columns of the parity check matrices H of the first new
15 LDPC codes of (64k, 7/15), (64k, 9/15), (64k, 11/15) and
(64k, 13/15), the column weight is X2 for next KY2
columns, the column weight is Y1 for next KY1 columns,
the column weight is Y2 for next KY2 columns, the column
weight is 2 for next M-1 columns, and the column weight
20 is 1 for a last column, respectively.
[0291] Herein, KX1 + KX2 + KY1 + KY2 + M-1 + 1 is
equal to the code length N = 64800 bits of the first new
LDPC codes of (64k, 7/15), (64k, 9/15), (64k, 11/15) and
(64k, 13/15).
25 [0292] Fig. 59 is a view showing the numbers of
columns KX1, KY2, KY1, KY2 and M, and the column weights
Xl, X2, Yl, and Y2 in Fig. 58 for the parity check
matrices H of the first new LDPC codes of (64k, 7/15),
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(64k, 9/15), (64k, 11/15) and (64k, 13/15).
[0293] As for the parity check matrices H of the first
new LDPC codes of (64k, 7/15), (64k, 9/15), (64k, 11/15)
and (64k, 13/15), as is the case with the parity check
matrix illustrated in Figs. 12 and 13, the column weight
of the column closer to the top (left) column tends to be
larger, so that the code bit closer to the top code bit
of the new LDPC code tends to be more tolerant to error
(have resistance to error).
[0294] Fig. 60 is a view showing a simulation result
of the BER/FER (bit error rate/frame error rate) of the
first new LDPC code of (64k, 7/15) measured using the
QPSK as the modulation scheme.
[0295] Fig. 61 is a diagram showing a simulation
result of measurement of BER/FER about the first new LDPC
code of (64k, 9/15) measured using the QPSK as the
modulation scheme.
[0296] Fig. 62 is a view showing a simulation result
of the BER/FER of the first new LDPC code of (64k, 11/15)
measured using the QPSK as the modulation scheme.
[0297] Fig. 63 is a view showing a simulation result
of the BER/FER of the first new LDPC code of (64k, 13/15)
measured using the QPSK as the modulation scheme.
[0298] In the simulation, the AWGN channel is supposed,
and 50 times is adopted as the number of times of
repetitive decoding C for decoding the LDPC code.
[0299] In Fig. 60 to Fig. 63, Es/No is plotted along
the abscissa and the BER/FER is plotted along the
CA 02924874 2016-03-18
72
ordinate. A solid line represents the BER, and a dotted
line represents the FER.
[0300] According to Fig. 60 to Fig. 63, as for the
first new LDPC codes of (64k, 7/15), (64k, 9/15), (64k,
11/15) and (64k, 13/15), excellent BER/FER are obtained.
Accordingly, it can confirm that a good communication
quality is ensured in the data transmission using the
first new LDPC codes of (64k, 7/15), (64k, 9/15), (64k,
11/15) and (64k, 13/15).
[0301] Fig. 64 is a view showing a minimum cycle
length and a performance threshold of the parity check
matrices H of the first new LDPC codes of (64k, 6/15),
(64k, 8/15), (64k, 10/15) and (64k, 12/15) shown in Fig.
34 to Fig. 37.
[0302] The parity check matrices H of the first new
LDPC codes of (16k, 6/15), (16k, 8/15), (16k, 10/15) and
(16k, 12/15) have no cycle-4.
[0303] The performance threshold of the first new LDPC
code of (16k, 6/15) is 0.01, the performance threshold of
the first new LDPC code of (16k, 8/15) is 0.805765, the
performance threshold of the first new LDPC code of (16k,
10/15) is 2.471011 and the performance threshold of the
first new LDPC code of (16k, 12/15) is 4.269922.
[0304] Fig. 65 is a view illustrating the parity check
matrices H of the first new LDPC codes of (16k, 6/15),
(16k, 8/15), (16k, 10/15) and (16k, 12/15) in Fig. 34 to
Fig. 37.
[0305] The column weight is X1 for first to KX1-th
CA 02924874 2016-03-18
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columns of the parity check matrices H of the first new
LDPC codes of (16k, 6/15), (16k, 8/15), (16k, 10/15) and
(16k, 12/15), the column weight is X2 for next KY2
columns, the column weight is Y1 for next KY1 columns,
the column weight is Y2 for next KY2 columns, the column
weight is 2 for next M-1 columns, and the column weight
is 1 for a last column, respectively.
[0306] Herein, KX1 + KX2 + KY1 + KY2 + M-1 + 1 is
equal to the code length N = 16200 bits of the first new
LDPC codes of (16k, 6/15), (16k, 8/15), (16k, 10/15) and
(16k, 12/15).
[0307] Fig. 66 is a view showing the numbers of
columns KX1, KY2, KY1, KY2, and M, and the column weights
X1, X2, Y1, and Y2 in Fig. 65 for the parity check
matrices H of the first new LDPC codes of (16k, 6/15),
(16k, 8/15), (16k, 10/15) and (16k, 12/15).
[0308] As for the parity check matrices H of the first
new LDPC codes of (16k, 6/15), (16k, 8/15), (16k, 10/15)
and (16k, 12/15), as is the case with the parity check
matrix illustrated in Figs. 12 and 13, the column weight
of the column closer to the top (left) column tends to be
larger, so that the code bit closer to the top code bit
of the new LDPC code tends to be more tolerant to error.
[0309] Fig. 67 is a view showing a simulation result
of the BER/FER (bit error rate/frame error rate) of the
first new LDPC code of (16k, 6/15) measured using the
QPSK as the modulation scheme.
[0310] Fig. 68 is a view showing a simulation result
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of the BER/FER of the first new LDPC code of (16k, 8/15)
measured using the QPSK as the modulation scheme.
[0311] Fig. 69 is a view showing a simulation result
of the BER/FER of the first new LDPC code of (16k, 10/15)
measured using the QPSK as the modulation scheme.
[0312] Fig. 70 is a view showing a simulation result
of the BER/FER of the first new LDPC code of (16k, 12/15)
measured using the QPSK as the modulation scheme.
[0313] In the simulation, the AWGN channel is supposed
as the communication channel 13 (Fig. 7), and 50 times is
adopted as the number of times of repetitive decoding C
for decoding the LDPC code.
[0314] In Fig. 67 to Fig. 70, Es/No is plotted along
the abscissa and the BER/FER is plotted along the
ordinate. A solid line represents the BER, and a dotted
line represents the FER.
[0315] According to Fig. 67 to Fig. 70, as for the
first new LDPC codes of (16k, 6/15), (16k, 8/15), (16k,
10/15) and (16k, 12/15), excellent BER/FER are obtained.
Accordingly, it can confirm that a good communication
quality is ensured in the data transmission using the
first new LDPC codes of (16k, 6/15), (16k, 8/15), (16k,
10/15) and (16k, 12/15).
[0316] Fig. 71 is a view showing a minimum cycle
length and a performance threshold of the parity check
matrix H of the first new LDPC code of (16k, 10/15) shown
in Fig. 38.
[0317] The parity check matrix H of the other first
CA 02924874 2016-03-18
new LDPC code of (16k, 10/15) has no cycle-4.
[0318] The performance threshold of the first other
new LDPC code of (16k, 10/15) is 1.35.
[0319] Fig. 72 is a view illustrating the parity check
5 matrix H of the first other new LDPC code of (16k, 10/15)
in Fig. 72.
[0320] The column weight is X for first to KX1-th
columns of the parity check matrix H of the first other
new LDPC code of (16k, 10/15), the column weight is Y1
10 for next KY1 columns, the column weight is Y2 for next
KY2 columns, the column weight is 2 for next M-1 columns,
and the column weight is 1 for a last column,
respectively.
[0321] Herein, KX1 + KX2 + KY1 + KY2 + M-1 + 1 is
15 equal to the code length N = 16200 bits of the first
other new LDPC code of (16k, 10/15).
[0322] Fig. 73 is a view showing the numbers of
columns KX, KY1, KY2, and M, and the column weights Xl,
X2, Yl, and Y2 in Fig. 72 for the code matrix H of the
20 first other new LDPC code of (16k, 10/15).
[0323] As for the parity check matrix H of the first
other new LDPC code of (16k, 10/15), as is the case with
the parity check matrix illustrated in Figs. 12 and 13,
the column weight of the column closer to the top (left)
25 column tends to be larger, so that the code bit closer to
the top code bit of the new LDPC code tends to be more
tolerant to error.
[0324] Fig. 74 is a view showing a simulation result
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of the BER of the first other new LDPC code of (16k,
10/15) measured using the BPSK as the modulation scheme.
[0325] In the simulation, the AWGN channel is supposed
as the communication channel 13 (Fig. 7), and 50 times is
adopted as the number of times of repetitive decoding C
for decoding the LDPC code.
[0326] In Fig. 74, Es/No is plotted along the abscissa
and the BER is plotted along the ordinate. [0327]
According to Fig. 74, as for the first other new
LDPC code of (16k, 10/15), excellent BER is obtained.
Accordingly, it can confirm that a good communication
quality is ensured in the data transmission using the
first other new LDPC code of (16k, 10/15).
[0328] Fig. 75 is a view showing a minimum cycle length
and a performance threshold of the parity check matrix H
of the other first new LDPC code of (16k, 12/15) shown in
Fig. 39.
[0329] The parity check matrices H of the first other
new LDPC code of (16k, 12/15) has no cycle-4.
[0330] The performance threshold of the first other
new LDPC code of (16k, 12/15) is 4.237556.
[0331] Fig. 76 is a view illustrating the parity check
matrix H of the first other new LDPC code of (16k, 12/15)
in Fig. 39.
[0332] The column weight is X1 for first to KX1-th
columns of the parity check matrix H of the first other
new LDPC code of (16k, 12/15), the column weight is X2
for next KY2 columns, the column weight is Y1 for next
CA 02924874 2016-03-18
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KY1 columns, the column weight is Y2 for next KY2 columns,
the column weight is 2 for next M-1 columns, and the
column weight is 1 for a last column, respectively.
[0333] Herein, KX1 + KX2 + KY1 + KY2 + M-1 + 1 is
equal to the code length N = 16200 bits of the first
other new LDPC code of (16k, 12/15).
[0334] Fig. 77 is a view showing the numbers of
columns KX1, KX2, KY1, KY2 and M, and the column weights
X1, X2, Yl, and Y2 in Fig. 76 for the code matrix H of
the first other new LDPC code of (16k, 12/15).
[0335] As for the parity check matrix H of the first
other new LDPC code of (16k, 12/15), as is the case with
the parity check matrix illustrated in Figs. 12 and 13,
the column weight of the column closer to the top (left)
column tends to be larger, so that the code bit closer to
the top code bit of the new LDPC code tends to be more
tolerant to error.
[0336] Fig. 78 is a view showing a simulation result
of the BER/FER (bit error rate/frame error rate) of the
first other new LDPC code of (16k, 12/15) measured using
the QPSK as the modulation scheme.
[0337] In the simulation, the AWGN channel is supposed
as the communication channel 13 (Fig. 7), and 50 times is
adopted as the number of times of repetitive decoding C
for decoding the LDPC code.
[0338] In Fig. 78, Es/No is plotted along the abscissa
and the BER is plotted along the ordinate. A solid line
represents the BER, and a dotted line represents the FER.
CA 02924874 2016-03-18
78
[0339] According to Fig. 78, as for the first other
new LDPC code of (16k, 12/15), excellent BER/FER is
obtained. Accordingly, it can confirm that a good
communication quality is ensured in the data transmission
using the first other new LDPC code of (16k, 12/15).
[0340] Fig. 79 is a view illustrating the parity check
matrices H of the second new LDPC codes of (64k, 6/15),
(64k, 8/15), (64k, 10/15) and (64k, 12/15) in Fig. 40 to
Fig. 50.
[0341] The column weight is X1 for first to KX1-th
columns of the parity check matrices H of the second new
LDPC codes of (64k, 6/15), (64k, 8/15), (64k, 10/15) and
(64k, 12/15), the column weight is X2 for next KY2
columns, the column weight is Y1 for next KY1 columns,
the column weight is Y2 for next KY2 columns, the column
weight is 2 for next M-1 columns, and the column weight
is 1 for a last column, respectively.
[0342] Herein, KX1 + KX2 + KY1 + KY2 + M-1 + 1 is
equal to the code length N = 64800 bits of the second new
LDPC codes of (64k, 6/15), (64k, 8/15), (64k, 10/15) and
(64k, 12/15).
[0343] Fig. 80 is a view showing the numbers of
columns KX1, KX2, KY1, KY2, and M, and the column weights
Xi, X2, Yl, and Y2 in Fig. 79 for the parity check
matrices H of the second new LDPC codes of (64k, 6/15),
(64k, 8/15), (64k, 10/15) and (64k, 12/15).
[0344] As for the parity check matrices H of the
second new LDPC codes of (64k, 6/15), (64k, 8/15), (64k,
CA 02924874 2016-03-18
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10/15) and (64k, 12/15), as is the case with the parity
check matrix illustrated in Figs. 12 and 13, the column
weight of the column closer to the top (left) column
tends to be larger, so that the code bit closer to the
top code bit of the new LDPC code tends to be more
tolerant to error.
[0345] Fig. 81 is a view showing a simulation result
of the BER/FER of the second new LDPC code of (64k, 6/15)
measured using the QPSK as the modulation scheme.
[0346] Fig. 82 is a view showing a simulation result
of the BER/FER of the second new LDPC code of (64k, 8/15)
measured using the QPSK as the modulation scheme.
[0347] Fig. 83 is a view showing a simulation result
of the BER/FER of the second new LDPC code of (64k,
10/15) measured using the QPSK as the modulation scheme.
[0348] Fig. 84 is a view showing a simulation result
of the BER/FER of the second new LDPC code of (64k,
12/15) measured using the QPSK as the modulation scheme.
[0349] In the simulation, the AWGN channel is supposed,
and 50 times is adopted as the number of times of
repetitive decoding C for decoding the LDPC code.
[0350] In Fig. 81 to Fig. 84, Es/No is plotted along
the abscissa and the BER/FER is plotted along the
ordinate. A solid line represents the BER, and a dotted
line represents the FER.
[0351] According to Fig. 81 to Fig. 84, as for the
second new LDPC codes of (64k, 6/15), (64k, 8/15), (64k,
10/15) and (64k, 12/15), excellent BER/FER are obtained.
CA 02924874 2016-03-18
Accordingly, it can confirm that a good communication
quality is ensured in the data transmission using the
second new LDPC codes of (64k, 6/15), (64k, 8/15), (64k,
10/15) and (64k, 12/15).
5 [0352] Fig. 85 is a view illustrating the parity check
matrices H of the second new LDPC codes of (64k, 7/15),
(64k, 9/15), (64k, 11/15) and (64k, 13/15) shown in Fig.
51 to Fig. 54.
[0353] The column weight is X1 for first to KX1-th
10 columns of the parity check matrices H of the second new
LDPC codes of (64k, 7/15), (64k, 9/15), (64k, 11/15) and
(64k, 13/15), the column weight is X2 for next KY2
columns, the column weight is Y1 for next KY1 columns,
the column weight is Y2 for next KY2 columns, the column
15 weight is 2 for next M-1 columns, and the column weight
is 1 for a last column, respectively.
[0354] Herein, KX1 + KX2 + KY1 + KY2 + M-1 + 1 is
equal to the code length N = 16200 bits of the second new
LDPC codes of (16k, 7/15), (16k, 9/15), (16k, 11/15) and
20 (16k, 13/15).
[0355] Fig. 86 is a view showing the numbers of
columns KX1, KX2, KY1, KY2, and M, and the column weights
Xl, X2, Yl, and Y2 in Fig. 85 for the parity check
matrices H of the second new LDPC codes of (16k, 7/15),
25 (16k, 9/15), (16k, 11/15) and (16k, 13/15).
[0356] As for the parity check matrices H of the
second new LDPC codes of (16k, 7/15), (16k, 9/15), (16k,
11/15) and (16k, 13/15), as is the case with the parity
CA 02924874 2016-03-18
81
check matrix illustrated in Figs. 12 and 13, the column
weight of the column closer to the top (left) column
tends to be larger, so that the code bit closer to the
top code bit of the new LDPC code tends to be more
tolerant to error.
[0357] Fig. 87 is a view showing a simulation result
of the BER/FER of the second new LDPC code of (16k, 7/15)
measured using the QPSK as the modulation scheme.
[0358] Fig. 88 is a view showing a simulation result
of the BER/FER of the second new LDPC code of (16k, 9/15)
measured using the QPSK as the modulation scheme.
[0359] Fig. 89 is a view showing a simulation result
of the BER/FER of the second new LDPC code of (16k,
11/15) measured using the QPSK as the modulation scheme.
[0360] Fig. 90 is a view showing a simulation result
of the BER/FER of the second new LDPC code of (16k,
13/15) measured using the QPSK as the modulation scheme.
[0361] In the simulation, the AWGN channel is supposed
as the communication channel 13 (Fig. 7), and 50 times is
adopted as the number of times of repetitive decoding C
for decoding the LDPC code.
[0362] In Fig. 87 to Fig. 90, Es/No is plotted along
the abscissa and the BER/FER is plotted along the
ordinate. A solid line represents the BER, and a dotted
line represents the FER.
[0363] According to Fig. 87 to Fig. 90, as for the
second new LDPC codes of (16k, 7/15), (16k, 9/15), (16k,
11/15) and (16k, 13/15), excellent BER/FER are obtained.
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Accordingly, it can confirm that a good communication
quality is ensured in the data transmission using the
first new LDPC codes of (16k, 7/15), (16k, 9/15), (16k,
11/15) and (16k, 13/15).
[0364] Fig. 79 to Fig. 90 are data provided from
Samsung.
[0365]
<Constellation>
[0366] Fig. 91 is a diagram showing illustrative types
of the constellation used in the transmission system in
Fig. 7.
[0367] In the transmission system in Fig. 7, the
constellation expected to be specified by ATSC3.0 may be
used.
[0368] Fig. 91 shows illustrative types of the
constellation expected to be used by ATSC3Ø
[0369] In the ATSC3.0, the constellation used in the
MODCOD that is a combination of the modulation scheme and
the LDPC code is set.
[0370] In the ATSC3.0, it is expected to use five
modulation schemes, i.e.õ QPSK, 16QAM, 64QAM, 256QAM
and 1024QAM (1kQAM).
[0371] In the ATSC3.0, it is expected to use 16 types
of the LDPC codes whose code rates r of eight types of
6/15, 7/15, 8/15, 9/15, 10/15, 11/15, 12/15 and 13/15 for
each of two types of code lengths N of 16k bits and 64k
bits.
[0372] In the ATSC3.0, 16 types of the LDPC codes are
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classified into 8 types (not depending on the code
lengths N) by the code rates r, and it is expected that
40 (= 8 x 5) combinations of 8 types of the LDPC codes
(each LDPC code whose code rate r is 6/15, 7/15, 8/15,
9/15, 10/15, 11/15, 12/15 or 13/15) and 5 types of the
modulation schemes are used as a MODCOD capable of
setting the constellation.
[0373] Accordingly, in the ATSC3.0, the MODCOD
represents the combination of the 8 types of the code
rates r of the LDPC codes and 5 types of the modulation
schemes.
[0374] In Fig. 91, "NUC_16_6/15" described in the
column "NUC Shape" represents the constellation used in
the MODCOD corresponding to the row of the column "NUC
Shape".
[0375] Herein, for example, the "NUC_16_6/15"
represents the constellation used in the MODCOD where the
modulation scheme is 16QAM and code rate r is the LDPC
code is 6/15.
[0376] As shown in Fig. 91, if the modulation scheme
is QPSK, the same constellation is used for the 8 types
of the code rates r of the LDPC code.
[0377] Also as shown in Fig. 91, if the modulation
scheme is 16QAM, 64QAM, 256QAM or 1024QAM, different
constellations are used for the 8 types of the code rates
r of the LDPC code.
[0378] Accordingly, in the ATSC3.0, one constellation
is prepared for QPSK, and eight constellations are
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prepared each for 16QAM, 64QAM, 256QAM and 1024QAM.
[0379] There are a UC (Uniform Constellation) where a
constellation of signal points is uniform and a NUC (Non
Uniform Constellation) where a constellation is not
uniform.
[0380] Also, there are constellations called as 1D NUC
(1-dimensional M2 - QAM non-uniform constellation), 2D NUC
(2-dimensional QQAM non-uniform constellation) and the
like.
[0381] As the constellation of QPSK, UC is used. As
the constellations of 16QAM, 64QAM and 256QAM, 2D NUC is
used, for example. As the constellations of 1024QAM, 1D
NUC is used, for example.
[0382] Fig. 92 is a diagram showing an example of the
constellation for the eight code rates r of the LDPC code
when the modulation scheme is 16QAM.
[0383] Fig. 93 is a diagram showing an example of the
constellation for the eight code rates r of the LDPC code
when the modulation scheme is 64QAM.
[0384] Fig. 94 is a diagram showing an example of the
constellation for the eight code rates r of the LDPC code
when the modulation scheme is 256QAM.
[0385] Fig. 95 is a diagram showing an example of the
constellation for the eight code rates r of the LDPC code
when the modulation scheme is 1024QAM.
[0386] In Fig. 92 to Fig. 95, each abscissa and each
ordinate are an I axis and a Q axis, Re{xl} and Im{x1}
represent a real part and an imaginary part of a signal
CA 02924874 2016-03-18
point xl as a coordinates of the signal point xl.
[0387] In Fig. 92 to Fig. 95, the numerical values
followed by "for CR" represent the code rates r of the
LDPC code.
5 [0388] The constellations where the code rates r of
the LDPC code are 7/15, 9/15, 11/15 and 13/15 are based
on the data provided from Samsung.
[0389] Fig. 96 is a view showing a simulation result
of measurement of BER when UC, 1D NUC or 2D NUC is used
10 as the constellation in the case of the modulation scheme
of 16QAM.
[0390] Fig. 97 is a view showing a simulation result
of measurement of BER when UC, 1D NUC or 2D NUC is used
as the constellation in the case of the modulation scheme
15 of 64QAM.
[0391] Fig. 98 is a view showing a simulation result
of measurement of BER when UC, 1D NUC or 2D NUC is used
as the constellation in the case of the modulation scheme
of 256QAM.
20 [0392] Fig. 99 is a view showing a simulation result
of measurement of BER when UC, 1D NUC or 2D NUC is used
as the constellation in the case of the modulation scheme
of 1024QAM.
[0393] In Fig. 96 to Fig. 99, SNR (Signal to Noise
25 Ratio) is plotted along the abscissa and the BER is
plotted along the ordinate.
[0394] If the modulation scheme is 16QAM, 64QAM or
256QAM, as shown in Fig. 96 to Fig. 98, it can confirm
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86
that the BER is much improved by 1D NUC than by UC, and
that the BER is further much improved by 2D NUC than by
1D NUC.
[0395] If the modulation scheme is 1024QAM, as shown
in Fig. 99, it can confirm that the BER is much improved
by 1D NUC than by UC.
[0396] Fig. 100 is a diagram showing coordinates of
the signal points of UC commonly used for eight code
rates r (= 6/15, 7/15, 8/15, 9/15, 10/15, 11/15, 12, 15
and 13/15) of the LDPC code when the modulation scheme is
. QPSK.
[0397] In Fig. 100, "Input cell word y" represents 2-
bit symbol of mapping by UC of the QPSK, and
"Constellation point zq" represents a coordinate of a
signal point zq. The index q of the signal point zq
represents a discrete-time of symbols (a time interval
between one symbol and the next symbol).
[0398] In Fig. 100, the coordinates of the signal
point zq are represented by a complex number, and i
represents the imaginary unit (r(-1)).
[0399] Fig. 101 is a diagram showing coordinates of
the signal points of 2D NUC commonly used for eight code
rates r of the LDPC code when the modulation scheme is
16QAM.
[0400] Fig. 102 is a diagram showing coordinates of
the signal points of 2D NUC commonly used for eight code
rates r of the LDPC code when the modulation scheme is
64QAM.
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87
[0401] Fig. 103 is a diagram showing coordinates of
the signal points of 2D NUC commonly used for eight code
rates r of the LDPC code when the modulation scheme is
256QAM.
[0402] In Fig. 101 to Fig. 103, NUC_2m_r represents a
coordinate of a signal point of 2D NUC used if the
modulation method is 2mQAM and the code rate of the LDPC
code is r.
[0403] In Fig. 101 to Fig. 103, as in Fig. 100, the
coordinate of the signal point zq is represented by a
complex number, and i represents the imaginary unit.
[0404] In Fig. 101 to Fig. 103, w#k represents a
coordinate of a signal point in a first quadrant of the
constellation.
[0405] In 2D NUC, a signal point of a second quadrant
of the constellation is arranged at a position where the
signal point of the first quadrant is moved symmetrically
with respect to the Q axis, and a signal point of a third
quadrant of the constellation is arranged at a position
where the signal point of the first quadrant is moved
symmetrically with respect to the origin. A signal point
of a fourth quadrant of the constellation is arranged at
a position where the signal point of the first quadrant
is moved symmetrically with respect to the I axis.
[0406] Herein, if the modulation scheme is 2m QAM, m
bits are taken as one symbol, and one symbol is mapped to
signal points corresponding to the symbol.
[0407] The symbol of the m bit symbol is represented,
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for example, by 0 to 2m -1 integer values. If b = 2m/4,
the symbols y(0), y(1), ¨=, y (2m-1) represented by 0 to
2m-1 integer values may be classified into four: symbols
y(0) to y(b-1), y(b) to y(2b-1), y(2b) to y(3b-1) and
y(3b) to (4b-1).
[0408] In Fig. 101 to Fig. 103, the suffix k of w#k
represents an integer value of 0 to b-1, and w#k
represents the coordinate of the signal point
corresponding to the symbol y(k) from the symbols y(0) to
y(b-1).
[0409] The coordinate of the signal point
corresponding to the symbol y(k+b) from the symbols y(b)
to y(2b-1) is represented by -conj(w#k). The coordinate
of the signal point corresponding to the symbol y(k+2b)
from the symbols y(2b) to y(3b-1) is represented by
conj(w#k). The coordinate of the signal point
corresponding to the symbol y(k+3b) from the symbols
y(3b) to y(4b-1) is represented by conj(w#k).
[0410] The conj(w#k) represents a complex conjugate of
w#k.
[0411] For example, if the modulation scheme is 16QAM,
m = 4 bit symbols; y(0), y(1), ¨=, y(15) are classified
into four; symbols y(0) to y(3), y(4) to y(7), y(8) to
y(11) and y(12) to y(15) as b = 24/4/4 = 4.
[0412] For example, as the symbol y(12) from the
symbols y(0) to y(15) is a symbol y(k+3b)y(0+3x4) from
the symbols y(3b) to y(4b-1) and k = 0, the coordinate of
the signal point corresponding to the symbol y(12) will
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be -w#k = -w0.
[0413] If the code rate r of the LDPC code, for
example, is 9/15, according to Fig. 101, w0 of
(NUC 16 9/15) where the modulation scheme is 16QAM and
_ _
the code rate r is 9/15 is 0.4909 + 1.2007i. So, a
coordinate -w0 of the signal point corresponding to the
symbol y(12) is -(0.4909 + 1.2007i).
[0414] Fig. 104 is a diagram showing coordinates of
the signal points of 1D NUC used for eight code rates r
of the LDPC code when the modulation scheme is 1024QAM.
[0415] In Fig. 104, the columns of NUC_lk_r represent
values of u#k of the coordinates of the signal points of
1D NUC used when the modulation scheme is 1024QAM and the
code rate of the LDPC code is r.
[0416] u#k represents a real part Re(zq) and an
imaginary part Im(zq) of the complex number as a
coordinate of the signal point zq of 1D NUC.
[0417] Fig. 105 is a diagram showing a relationship
between the real part Re(zq) and the imaginary part
Im(zci) of the complex number as the coordinate of the
signal point zq of 1D NUC corresponding to the symbol y.
[0418] The 10-bit symbol y of 1024QAM is represented
by yo, q, yi, qf Y2, GI, Y3, q, y4, (If Y5, q, Y6, q, Y7, cif Y8, q and
y9, q from the head bit (Most Significant Bit).
[0419] Fig. 105A represents a corresponding
relationship between odd numbered 5-bit symbol y; yo, q, y2,
q, y4, q, y6, q and 176, q and the u#k representing the real
part Re(zq) of (the coordinate) of the signal point zq
CA 02924874 2016-03-18
corresponding to the symbol y.
[0420] Fig. 105B represents a corresponding
relationship between even numbered 5-bit symbol y; i, q,
Y3, q, ys, q, 17-7, q and y9, q and the u#k representing the
5 imaginary part Im(zq) of (the coordinate) of the signal
point zq corresponding to the symbol y.
[0421] If the 10-bit symbol y = (yo, q, yi, q, y2, q, y3, q,
Y4, qf Y5, q, Y6, qr Y7, qf Y8, q and Yg, q) of 1024QAM is, for
example, (0, 0, 1, 0, 0, 1, 1, 1, 0, 0), odd-numbered 5
10 bits (yo, q, y2, q, 174, q, y6, q and y6, q) are (0, 1, 0, 1, 0)
and the even-numbered 5 bits (y2, q, y3, q, y5, q, y7, q and y9,
q) are (0, 0, 1, 1, 0).
[0422] In Fig. 105A, the odd-numbered 5 bits (0, 1, 0,
1, 0) are correlated with u3, and therefore, the real
15 part Re(zq) of the signal point zq corresponding to the
symbol y = (0, 0, 1, 0, 0, 1, 1, 1, 0, 0) is u3.
[0423] In Fig. 105B, the even-numbered 5 bits (0, 1, 0,
1, 0) are correlated with ull, and therefore, the
imaginary part Im(zq) of the signal point zq corresponding
20 to the symbol y = (0, 0, 1, 0, 0, 1, 1, 1, 0, 0) is ull.
[0424] If the code rate r of the LDPC code, for
example, is 7/15, according to Fig. 104 as described
above, as to 1D NUC (NUC_1k_7/15) where the modulation
scheme is 1024QAM and code rate r is the LDPC coding is
25 7/15, u3 is 1.04 and ull is 6.28.
[0425] Accordingly, in the real part Re(zq) of the
signal point zq corresponding to the symbol y = (0, 0, 1,
0, 0, 1, 1, 1, 0, 0), u3 = 1.04, in Im(zq), ull = 6.28.
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As a result, the coordinate of the signal point zq
corresponding to the symbol y = (0, 0, 1, 0, 0, 1, 1, 1,
0, 0) is represented by 1.04 + 6.28i.
[0426] The signal points of 1D NUC are arranged in a
matrix on a straight line parallel to the I axis or a
straight line parallel to the Q-axis. However, spaces
between signal points are not constant. Upon transmission
of (data mapped to) the signal points, the average power
of the signal points on the constellation is normalized.
Normalization is performed by multiplying each signal
point zq on the constellation by a reciprocal 1/ (rPave) of
a square root rPave Of a root mean square value Pave, where
the root mean square of absolute values of (coordinates
of) all signal points on the constellation is represented
by Pave.
[0427] By the constellations illustrated in Fig. 92 to
Fig. 105, it can confirm that good error rates are
obtained.
[0428]
<Block interleaver 25>
[0429] Fig. 106 is a block diagram showing a
configuration example of a block interleaver 25 in Fig. 9.
[0430] The block interleaver 25 has a storage region
called as Part 1 and a storage region called as Part 2.
[0431] The Parts 1 and 2 store one bit in a row
(horizontal) direction. The number C of columns that are
the storage regions for storing the predetermined number
of bits in a column (vertical) direction are arranged.
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The number C is equal to the number of bits m of the
symbols.
[0432] When the number of bits that are stored by the
part 1 columns in the column direction (hereinafter, also
referred to as a part-column length) is expressed as R1,
and the part column length of the part 2 columns is
expressed as R2, (R1 + R2) x C equals to the code length
N of the target of the LDPC code to be block-interleaved
(in the present embodiment, 64800 bits, or 16200 bits).
[0433] In addition, a part column length R1 is equal
to a multiple of 360 bits that are the number of columns
P being the unit of the cyclic structure. A part column
length R2 is equal to a remainder when the sum of the
part column length R1 of the part 1 and the part column
length R2 of the part 2 (hereinafter also referred to as
a column length) R1 + R2 is divided by 360 bits that are
the number of columns P being the unit of the cyclic
structure.
[0434] Here, the column length R1 + R2 is equal to a
value when the code length N of the LDPC code to be
block-interleaved is divided by the bit number.m of
symbols.
[0435] For example, concerning the LDPC code whose
code length N is 16200 bits, if 16QAM is used as the
modulation method, the bit number m of symbols is four
bits, and the column length R1 + R2 will be 4050 (-
16200/4) bits.
[0436] Furthermore, as the remainder when the column
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length Rl + R2 = 4050 is divided by 360 bits that are the
number of columns P being the unit of the cyclic
structure is 90, the part column length R2 will be 90
bits.
[0437] The part column length Rl of the part 1 will be
R1 + R2 - R2 = 4050-90 = 3960 bits.
[0438] Fig. 107 is a diagram showing the column number
C of the parts 1 and 2 for a combination of the code
length N and the modulation scheme and the part column
lengths (row numbers) R1 and R2.
[0439] Fig. 107 shows the column number C of the parts
1 and 2 and the part column lengths R1 and R2 for a
combination of the code length N of the LDPC code being
16200 bits and 64800 bits and the modulation schemes of
16QAM, 64QAM, 256QAM, and 1024QAM.
[0440] Fig. 108 is a diagram for illustrating a block
interleave performed in the block interleaver 25.
[0441] The block interleaver 25 preforms the block
interleave to the parts 1 and 2 by writing and reading
the LDPC code.
[0442] In other words, in the block interleave, as
shown in Fig. 108A, the code bits of the LDPC code of one
code word are written from a top to down direction
(column direction) of the part 1 columns and from left to
right directions of the columns.
[0443] When writing of the code bits to the bottom of
the right-most column of the part 1 columns (C-th column)
is finished, the rest of the code bits is written from a
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top to down direction (column direction) of the part 2
columns and from left to right directions of the columns.
[0444] After that, when the writing of the code bits
to the bottom of the right-most column of the part 2
columns (C-th column) is finished, as shown in Fig. 108B,
the code bits are read in a C - m bit unit in the row
direction from all first columns of the number C of the
part 1.
[0445] The code bits for all columns of the number C
of the part 1 are read sequentially to the lower rows.
When the reading is finished for the last Rlth row, the
code bits are read in a C = m bit unit in the row
direction from all first columns of the number C of the
part 2.
[0446] The code bits for all columns of the number C
of the part 2 are read sequentially to the lower rows for
the last R2th row.
[0447] As described above, the code bits read from the
parts 1 and 2 for m-bit unit are supplied to the mapper
117 (Fig. 8) as the symbols.
[0448]
<Group-wise interleave>
[0449]
Fig. 109 is a diagram for illustrating group-wise
interleave performed in the group-wise interleaver 24 in
Fig. 9.
[0450] In the group-wise interleave, the LDPC code for
one code word is divided into a 360-bit unit equal to the
CA 02924874 2016-03-18
number of columns P being the unit of the cyclic
structure from the beginning. One division, i.e., 360-bit,
is considered as a bit group. The LDPC code of one code
word is interleaved in a bit group unit according to a
5 predetermined pattern (hereinafter also referred to as a
GW pattern).
[0451] Here, the i + lth bit group from the beginning
at the time of dividing the one code word of the LDPC
code to the bit group is hereinafter also described as a
10 bit group i.
[0452] For example, the LDPC code whose code length N
of 1800 bits is divided into 5 (= 1800/360) bit groups: 0,
1, 2, 3, 4. Further, for example, the LDPC codes whose
code length N of 16200 bits is divided into 45 (=
15 16200/360) bit groups: 0, 1, ..., 44. The LDPC whose code
length N of 64800 bits is divided into 180 (= 64800/360)
bit groups: 0, 1, ..., 179.
[0453] In the following, the GW pattern will be
represented by a sequence of numbers representing the bit
20 groups. For example, for the LDPC code whose code length
N of 1800 bits, the GW pattern 4, 2, 0, 3, 1 represents
that a sequence of the bit groups 0, 1, 2, 3, 4, is
interleaved (changed) to a sequence of the bit groups 4,
2, 0, 3, 1.
25 [0454] The GW pattern can be set for, at least, each
code length N of the LDPC code.
[0455] Fig. 110 is a diagram showing a first example
of a GW pattern for the LDPC code whose code length N of
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64k bits.
[0456] According to the GW pattern in Fig. 110, a
sequence of the bit groups 0 to 179 having the LDPC code
of 64k bits is interleaved to a sequence of a bit group
of
178, 140, 44, 100, 107, 89, 169, 166, 36, 52, 33, 160, 14,
165, 109, 35, 74, 136, 99, 97, 28, 59, 7, 29, 164, 119,
41, 55, 17, 115, 138, 93, 96, 24, 31, 179, 120, 91, 98,
43, 6, 56, 148, 68, 45, 103, 5, 4, 10, 58, 1, 76, 112,
124, 110, 66, 0, 85, 64, 163, 75, 105, 117, 87, 159, 146,
34, 57, 145, 143, 101, 53, 123, 48, 79, 13, 134, 71, 135,
81, 125, 30, 131, 139, 46, 12, 157, 23, 127, 61, 82, 84,
32, 22, 94, 170, 167, 126, 176, 51, 102, 171, 18, 104, 73,
152, 72, 25, 83, 80, 149, 142, 77, 137, 177, 19, 20, 173,
153, 54, 69, 49, 11, 156, 133, 162, 63, 122, 106, 42, 174,
88, 62, 78, 86, 116, 155, 129, 3, 9, 47, 50, 144, 114,
154, 121, 161, 92, 37, 38, 39, 108, 95, 70, 113, 141, 15,
147, 151, 111, 2, 118, 158, 60, 132, 168, 150, 21, 16,
175, 27, 90, 128, 130, 67, 172, 65, 26, 40, 8.
[0457] Fig. 111 is a diagram showing a second example
of the GW pattern for the LDPC code whose code length N
of 64k bits.
[0458] According to the GW pattern in Fig. 111, a
sequence of the bit groups 0 to 179 having the LDPC code
of 64k bits is interleaved to a sequence of a bit group
of
32, 84, 49, 56, 54, 99, 76, 178, 65, 48, 87, 125, 121, 51,
130, 70, 90, 2, 73, 123, 174, 20, 46, 31, 3, 89, 16, 66,
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30, 158, 19, 137, 0, 12, 153, 147, 91, 33, 122, 57, 36,
129, 135, 24, 168, 141, 52, 71, 80, 96, 50, 44, 10, 93,
81, 22, 152, 29, 41, 95, 172, 107, 173, 42, 144, 63, 163,
43, 150, 60, 69, 58, 101, 68, 62, 9, 166, 78, 177, 146,
118, 82, 6, 21, 161, 4, 169, 18, 106, 176, 162, 175, 117,
8, 128, 97, 100, 111, 23, 114, 45, 34, 165, 28, 59, 131,
143, 83, 25, 61, 105, 35, 104, 156, 38, 102, 85, 142, 164,
26, 17, 160, 109, 40, 11, 47, 72, 124, 79, 7, 136, 159,
67, 1, 5, 14, 94, 110, 98, 145, 75, 149, 119, 74, 55, 155,
115, 113, 53, 151, 39, 92, 171, 154, 179, 139, 148, 103,
86, 37, 27, 77, 157, 108, 167, 13, 127, 126, 120, 133,
138, 134, 140, 116, 64, 88, 170, 132, 15, 112.
[0459] Fig. 112 is a diagram showing a third example
of the GW pattern for the LDPC code whose code length N
of 64k bits.
[0460] According to the GW pattern in Fig. 112, a
sequence of the bit groups 0 to 179 having the LDPC code
of 64k bits is interleaved to a sequence of a bit group
of
90, 64, 100, 166, 105, 61, 29, 56, 66, 40, 52, 21, 23, 69,
31, 34, 10, 136, 94, 4, 123, 39, 72, 129, 106, 16, 14,
134, 152, 142, 164, 37, 67, 17, 48, 99, 135, 54, 2, 0,
146, 115, 20, 76, 111, 83, 145, 177, 156, 174, 28, 25,
139, 33, 128, 1, 179, 45, 153, 38, 62, 110, 151, 32, 70,
101, 143, 77, 130, 50, 84, 127, 103, 109, 5, 63, 92, 124,
87, 160, 108, 26, 60, 98, 172, 102, 88, 170, 6, 13, 171,
97, 95, 91, 81, 137, 119, 148, 86, 35, 30, 140, 65, 82,
49, 46, 133, 71, 42, 43, 175, 141, 55, 93, 79, 107, 173,
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78, 176, 96, 73, 57, 36, 44, 154, 19, 11, 165, 58, 18, 53,
126, 138, 117, 51, 113, 114, 162, 178, 3, 150, 8, 22, 131,
157, 118, 116, 85, 41, 27, 80, 12, 112, 144, 68, 167, 59,
75, 122, 132, 149, 24, 120, 47, 104, 147, 121, 74, 155,
125, 15, 7, 89, 161, 163, 9, 159, 168, 169, 158.
[0461] Fig. 113 is a diagram showing a fourth example
of the GW pattern for the LDPC code whose code length N
of 64k bits.
[0462] According to the GW pattern in Fig. 113, a
sequence of the bit groups 0 to 179 having the LDPC code
of 64k bits is interleaved to a sequence of a bit group
of
0, 154, 6, 53, 30, 97, 105, 121, 12, 156, 94, 77, 47, 78,
13, 19, 82, 60, 85, 162, 62, 58, 116, 127, 48, 177, 80,
138, 8, 145, 132, 134, 90, 28, 83, 170, 87, 59, 49, 11,
39, 101, 31, 139, 148, 22, 37, 15, 166, 1, 42, 120, 106,
119, 35, 70, 122, 56, 24, 140, 136, 126, 144, 167, 29,
163, 112, 175, 10, 73, 41, 99, 98, 107, 117, 66, 17, 57,
7, 151, 51, 33, 158, 141, 150, 110, 137, 123, 9, 18, 14,
71, 147, 52, 164, 45, 111, 108, 21, 91, 109, 160, 74, 169,
88, 63, 174, 89, 2, 130, 124, 146, 84, 176, 149, 159, 155,
44, 43, 173, 179, 86, 168, 165, 95, 135, 27, 69, 23, 65,
125, 104, 178, 171, 46, 55, 26, 75, 129, 54, 153, 114,
152, 61, 68, 103, 16, 40, 128, 3, 38, 72, 92, 81, 93, 100,
34, 79, 115, 133, 102, 76, 131, 36, 32, 5, 64, 143, 20,
172, 50, 157, 25, 113, 118, 161, 142, 96, 4, 67.
[0463] Fig. 114 is a diagram showing a first example
of a GW pattern for the LDPC code whose code length N of
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16k bits.
[0464] According to the GW pattern in Fig. 114, a
sequence of the bit groups 0 to 44 having the LDPC code
of 16k bits is interleaved to a sequence of a bit group
of
15, 23, 9, 19, 5, 29, 4, 25, 8, 41, 13, 2, 22, 12, 26, 6,
37, 17, 38, 7, 20, 1, 39, 34, 18, 31, 10, 44, 32, 24, 14,
42, 11, 30, 27, 3, 36, 40, 33, 21, 28, 43, 0, 16, 35.
[0465] Fig. 115 is a diagram showing a second example
of the GW pattern for the LDPC code whose code length N
of 16k bits.
[0466] According to the GW pattern in Fig. 115, a
sequence of the bit groups 0 to 44 having the LDPC code
of 16k bits is interleaved to a sequence of a bit group
of
6, 14, 24, 36, 30, 12, 33, 16, 37, 20, 21, 3, 11, 26, 34,
5, 7, 0, 1, 18, 2, 22, 19, 9, 32, 28, 27, 23, 42, 15, 13,
17, 35, 25, 8, 29, 38, 40, 10, 44, 31, 4, 43, 39, 41.
[0467] Fig. 116 is a diagram showing a third example
of the GW pattern for the LDPC code whose code length N
of 16k bits.
[0468] According to the GW pattern in Fig. 116, a
sequence of the bit groups 0 to 44 having the LDPC code
of 16k bits is interleaved to a sequence of a bit group
of
21, 0, 34, 5, 16, 7, 1, 25, 9, 24, 19, 11, 6, 15, 39, 38,
42, 30, 18, 14, 13, 23, 20, 33, 3, 10, 4, 8, 26, 27, 41,
40, 31, 2, 35, 37, 43, 22, 17, 12, 29, 36, 28, 32, 44.
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[0469] Fig. 117 is a diagram showing a fourth example
of the GW pattern for the LDPC code whose code length N
of 16k bits.
[0470] According to the GW pattern in Fig. 117, a
sequence of the bit groups 0 to 44 having the LDPC code
of 16k bits is interleaved to a sequence of a bit group
of
15, 25, 9, 27, 5, 38, 13, 10, 19, 16, 28, 1, 36, 0, 11,
17, 32, 35, 7, 26, 14, 21, 6, 4, 23, 22, 3, 18, 20, 24,
30, 12, 37, 2, 40, 8, 33, 29, 31, 34, 41, 42, 43, 44, 39.
[0471] For the group-wise interleave, the GW pattern
is set for each combination of the code rate r of the
LDPC code and the modulation scheme other than the code
length N of the LDPC code, thereby improving the bit
error rate for each combination.
[0472] However, if the GW pattern is set individually
for all combination of the code length N and code rate r
is the LDPC code and the modulation scheme, the GW
pattern should be changed every time the LDPC code and
the modulation scheme used in the transmitting device 11
are changed. As a result, the processing becomes complex.
[0473] For the group-wise interleave, for example, the
code rate r of the LDPC code is classified into a low
rate (e.g., 6/15, 7/15, 8/15, 9/15) and a high rate (e.
g., 10/15, 11/15, 12/15, 13/15). The GW pattern can be
set for each combination of the code length N of the LDPC
code of 16k bits or 64k bits, the code rate r of the LDPC
code of the low rate or the high rate, and the modulation
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scheme of 16QAM, 64QAM, 256QAM or 1024QAM.
[0474] When the above-described combination of the
code length N, the code rate r and the modulation scheme
is expressed by (the code length N, the code rate r, the
modulation scheme), 16 combinations of the code length N,
the code rate r and the modulation scheme can be
supposed: (16k, low rate, 16QAM), (16k, low rate, 64QAM),
(16k, low rate, 256QAM), (16k, low rate, 1024QAM), (16k,
high rate, 16QAM), (16k, high rate, 64QAM), (16k, high
rate, 256QAM), (16k, high rate, 1024QAM), (64k, low rate,
16QAM), (64k, low rate, 64QAM), (64k, low rate, 256QAM),
(64k, low rate, 1024QAM), (64k, high rate, 16QAM), (64k,
high rate, 64QAM), (64k, high rate, 256QAM) and (64k,
high rate, 1024QAM), for example.
[0475] For the combination of code length N of the
LDPC code set to 64k: (64k, low rate, 16QAM), (64k, low
rate, 64QAM), (64k, low rate, 256QAM), (64k, low rate,
1024QAM), (64k, high rate, 16QAM), (64k, high rate,
64QAM), (64k, high rate, 256QAM) and (64k, high rate,
1024QAM), the GW pattern that most improves the error
rate can be applied among the four GW patterns shown in
Fig. 110 to Fig. 113.
[0476] For example, the GW pattern in Fig. 110 can be
applied to the combination (64k, high rate, 16QAM), the
GW pattern in Fig. 111 can be applied to the combination
(64k, low rate, 64QAM), the GW pattern in Fig. 112 can be
applied to the combination (64k, high rate, 256QAM), the
GW pattern in Fig. 113 can be applied to the combination
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(64k, low rate, 1024QAM), respectively.
[0477] For the combination of code length N of the
LDPC code is set to 16k: (16k, low rate, 16QAM), (16k,
low rate, 64QAM), (16k, low rate, 256QAM), (16k, low rate,
1024QAM), (16k, high rate, 16QAM), (16k, high rate,
64QAM), (16k, high rate, 256QAM) and (16k, high rate,
1024QAM), the GW pattern that most improves the error
rate can be applied among the four GW patterns shown in
Fig. 114 to Fig. 117.
[0478] For example, the GW pattern in Fig. 114 can be
applied to the combination (16k, low rate, 16QAM), the GW
pattern in Fig. 115 can be applied to the combination
(16k, high-rate, 64QAM), the GW pattern in Fig. 116 can
be applied to the combination (16k, low rate, the 256QAM),
and the GW pattern in Fig. 117 can be applied to the
combination (16k, high rate, in 1024QAM), respectively.
[0479] According to simulation by the present
inventors, for the GW pattern in Fig. 110, it was
confirmed that it is especially possible to achieve good
error rate in the combination of each of the second new
LDPC code of (64k, 10/15), the first new LDPC code of
(64k, 11/15), the second new LDPC code of (64k, 12/15)
and the first new LDPC code of (64k, 13/15) and the
modulation scheme 16QAM of which the constellation is
illustrated in Fig. 92 to Fig. 105.
[0480] For the GW pattern in Fig. 111, it was
confirmed that it is especially possible to achieve good
error rate in the combination of each of the second new
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LDPC code of (64k, 6/15), the first new LDPC code of (64k,
7/15), the second new LDPC code of (64k, 8/15) and the
first new LDPC code of (64k, 9/15) and the modulation
scheme 64QAM of which the constellation is illustrated in
Fig. 92 to Fig. 105.
[0481] For the GW pattern in Fig. 112, it was
confirmed that it is especially possible to achieve good
error rate in the combination of each of the second new
LDPC code of (64k, 10/15), the first new LDPC code of
(64k, 11/15), the second new LDPC code of (64k, 12/15)
and the first new LDPC code of (64k, 13/15) and the
modulation scheme 256QAM of which the constellation is
illustrated in Fig. 92 to Fig. 105.
[0482] For the GW pattern in Fig. 113, it was
confirmed that it is especially possible to achieve good
error rate in the combination of each of the second new
LDPC code of (64k, 6/15), the first new LDPC code of (64k,
7/15), the second new LDPC code of (64k, 8/15) and the
first new LDPC code of (64k, 9/15) and the modulation
scheme 1024QAM of which the constellation is illustrated
in Fig. 92 to Fig. 105.
[0483] For the GW pattern in Fig. 114, it was
confirmed that it is especially possible to achieve good
error rate in the combination of each of the first new
LDPC code of (16k, 6/15), the second new LDPC code of
(16k, 7/15), the first new LDPC code of (16k, 8/15) and
the second new LDPC code of (16k, 9/15) and the
modulation scheme 16QAM of which the constellation is
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illustrated in Fig. 92 to Fig. 105.
[0484] For the GW pattern in Fig. 115, it was
confirmed that it is especially possible to achieve good
error rate in the combination of each of the first new
LDPC code of (16k, 10/15), the second new LDPC code of
(16k, 11/15), the first new LDPC code of (16k, 12/15) and
the second new LDPC code of (16k, 13/15) and the
modulation scheme 64QAM of which the constellation is
illustrated in Fig. 92 to Fig. 105.
[0485] For the GW pattern in Fig. 116, it was
confirmed that it is especially possible to achieve good
error rate in the combination of each of the first new
LDPC code of (16k, 6/15), the second new LDPC code of
(16k, 7/15), the first new LDPC code of (16k, 8/15) and
the second new LDPC code of (16k, 9/15) and the
modulation scheme 256QAM of which the constellation is
illustrated in Fig. 92 to Fig. 105.
[0486] For the GW pattern in Fig. 117, it was
confirmed that it is especially possible to achieve good
error rate in the combination of each of the first new
LDPC code of (16k, 10/15), the second new LDPC code of
(16k, 11/15), the first new LDPC code of (16k, 12/15) and
the second new LDPC code of (16k, 13/15) and the
modulation scheme 1024QAM of which the constellation is
illustrated in Fig. 92 to Fig. 105.
[0487]
<Configuration Example of Receiving Apparatus 12>
[0488]
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Fig. 118 is a block diagram showing a configuration
example of the receiving device 12 in Fig. 7.
[0489] An OFDM operation 151 receives the OFDM signal
from the transmitting device 11 (Fig. 7) and performs
signal processing of the OFDM signal. The data obtained
by the signal processing by the OFDM operation 151 is
supplied to a frame management 152.
[0490] The frame management 152 performs processing of
the frame (frame interpretation) configured of the data
supplied from the OFDM operation 151 and supplies the
signal of the target data and the signal of the control
data obtained as a result to frequency deinterleavers 161
and 153.
[0491] The frequency deinterleaver 153 performs
frequency deinterleave in a symbol unit for the data from
the frame management 152 to supply to a demapper 154.
[0492] The demapper 154 demaps (performs signal point
constellation decoding) the data (data on the
constellation) from the frequency deinterleaver 153 based
on the signal arrangement (constellation) determined by
the orthogonal modulation performed at the transmitting
device 11 to perform the orthogonal demodulation thereof
and supplies the data ((likelihood) of the LDPC code)
obtained as a result to a LDPC decoder 155.
[0493] The LDPC decoder 155 performs LDPC decoding of
the LDPC code from the demapper 154 and supplies the LDPC
target data (herein, a BCH code) obtained as a result to
a BCH decoder 156.
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[0494] The BCH decoder 156 performs BCH decoding of the
LDPC target data from the LDPC decoder 155 and outputs
the control data (signaling) obtained as a result.
[0495] On the other hand, the frequency deinterleaver
161 performs the frequency deinterleave in a symbol unit
for the data from the frame management 152 to supply to a
SISO/MISO decoder 162.
[0496] The SISO/MISO decoder 162 performs time-space
decoding of the data from the frequency deinterleaver 161
to supply to a time deinterleaver 163.
[0497] The time deinterleaver 163 performs time
deinterleave of the data from the SISO/MISO decoder 162
in a symbol unit to supply to a demapper 164.
[0498] The demapper 164 demaps (performs signal point
constellation decoding) the data (data on the
constellation) from the time deinterleaver 163 based on
the signal point arrangement (constellation) determined
by the orthogonal modulation performed at the
transmitting device 11 to perform the orthogonal
demodulation thereof and supplies the data obtained as a
result to a bit deinterleaver 165.
[0499] The bit deinterleaver 165 performs bit
deinterleave of the data from the demapper 164 and
supplies (the likelihood of) the LDPC code obtained as a
result to an LDPC decoder 166.
[0500] The LDPC decoder 166 performs the LDPC decoding
of the LDPC code from the bit deinterleaver 165 and
supplies the LDPC target data (herein, the BCH code)
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obtained as a result to a BCH decoder 167.
[0501] The BCH decoder 167 performs the BCH decoding
of the LDPC target data from the LDPC decoder 155 and
supplies the data obtained as a result to a BB
descrambler 168.
[0502] The BB descrambler 168 applies a BB descramble
to the data from the BCH decoder 167 and supplies the
data obtained as a result to a null deletion 169.
[0503] The null deletion 169 deletes the null inserted
by the padder 112 in Fig. 8 from the data from the BB
descrambler 168 and supplies the same to a demultiplexer
170.
[0504] The demultiplexer 170 separates one or more
streams (target data) multiplexed into the data from the
null deletion 169 and outputs the same as output streams.
[0505] The receiving device 12 may be configured
without including some of the blocks shown in Fig. 48. In
other words, if the transmitting device 11 (Fig. 8) is
configured without including the time interleaver 118,
the SISO/MISO encoder 119, the frequency interleaver 120,
and frequency interleaver 124, for example, the receiving
device 12 may be configured without including the time
deinterleaver 163, the SISO/MISO decoder 162, the
frequency deinterleaver 161, and frequency deinterleaver
153 that are the blocks corresponding to the time
interleaver 118, the SISO/MISO encoder 119, the frequency
interleaver 120, and frequency interleaver 124 of the
transmitting device 11, respectively.
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[0506]
<Configuration Example of Bit Deinterleaver>
[0507] Fig. 119 is a block diagram showing a
configuration example of the bit deinterleaver 165 in Fig.
118.
[0508] The bit deinterleaver 165 configured of a block
deinterleaver 54 and a group-wise deinterleaver 55 and
performs the (bit) deinterleave of the symbol bit of the
data from the demapper 164 (Fig. 118).
[0509] That is to say, the block deinterleaver 54
performs a block deinterleave (an inverse process of
block interleave) corresponding to the block interleave
performed by the block interleaver 25 in Fig. 9, that is
to say, the block deinterleave to return the positions of
(the likelihood of) the code bits of the LDPC code
interchanged by the block interleave to the original
positions to the symbol bit of the symbol from the
demapper 164 and supplies the LDPC code obtained as a
result to the group-wise deinterleaver 55.
[0510] The group-wise deinterleaver 55 performs group-
wise deinterleave (inverse process of the group-wise
interleave) corresponding to the group-wise interleave
performed by the group-wise interleaver 24 in Fig. 9,
that is to say, the group-wise deinterleave to return the
code bits of the LDPC code of which arrangement is
changed by the group-wise interleave illustrated in Fig.
110 to Fig. 117 in a bit group unit are rearranged in a
bit group unit to the original arrangement to the LDPC
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code from the block deinterleaver 54.
[0511] If the parity interleave, the group-wise
interleave, and the block interleave are applied to the
LDPC code supplied from the demapper 164 to the bit
deinterleaver 165, the bit deinterleaver 165 may perform
all of parity deinterleave (inverse process of the parity
interleave, that is to say, the parity deinterleave to
return the code bits of the LDPC code, the arrangement of
which is changed by the parity interleave, to the
original arrangement) corresponding to the parity
interleave, the block deinterleave corresponding to the
block interleave, and the group-wise deinterleave
corresponding to the group-wise interleave.
[0512] Note that the bit deinterleaver 165 in Fig. 119
includes the block deinterleaver 54 that performs the
block deinterleave corresponding to the block interleave,
and the group-wise deinterleaver 55 that performs the
group-wise deinterleave corresponding to the group-wise
interleave, but includes no block for performing the
parity deinterleave corresponding to the parity
interleave, and the parity deinterleave is not performed.
[0513] Therefore, the LDPC code, to which the block
deinterleave and the group-wise deinterleave are applied
and the parity deinterleave is not applied, is supplied
from (the group-wise deinterleaver 55 of) the bit
deinterleaver 165 to the LDPC decoder 166.
[0514] The LDPC decoder 166 performs the LDPC decoding
of the LDPC code from the bit deinterleaver 165 using the
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conversion parity check matrix obtained by at least
applying the column permutation corresponding to the
parity interleave to the parity check matrix H used by
the LDPC encoder 115 in Fig. 8 in the LDPC encoding and
outputs the data obtained as a result as a decoding
result of the LDPC target data.
[0515] Fig. 120 is a flowchart illustrating processes
performed by the demapper 164, the bit deinterleaver 165,
and the LDPC decoder 166 in Fig. 119.
[0516] At step S111, the demapper 164 demaps the data
from the time deinterleaver 163 (data mapped onto the
signal point on the constellation) to perform the
orthogonal demodulation and supplies the same to the bit
deinterleaver 165, then the process shifts to S112.
[0517] At step S112, the bit deinterleaver 165
performs the deinterleave (bit deinterleave) from the
demapper 164 and the process shifts to step S113.
[0518] . That is to say, at step S112, the block
deinterleaver 54 performs in the bit deinterleaver 165
the block deinterleave of the data (symbol) from the
demapper 164 and supplies the code bit of the LDPC code
obtained as a result to the group-wise deinterleaver 55.
[0519] The group-wise deinterleaver 55 performs the
group-wise deinterleave to the LDPC code from the block
deinterleaver 54 and supplies (the likelihood of) the
LDPC code obtained as a result to the LDPC decoder 166.
[0520] At step S113, the LDPC decoder 166 performs the
LDPC decoding of the LDPC code from the group-wise
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deinterleaver 55 using the conversion parity check matrix
H used by the LDPC encoder 115 in Fig. 8 in the LDPC
encoding, i.e., using the conversion parity check matrix
obtained by at least applying the column permutation
corresponding to the parity interleave to the parity
check matrix H and outputs the data obtained as a result
to the BCH decoder 167 as the decoding result of the LDPC
target data.
[0521] Although the block deinterleaver 54, which
performs the block deinterleave, and the group-wise
deinterleaver 55, which performs the group-wise
deinterleave, are separately formed also in Fig. 119 as
in Fig. 9 for convenience of description, the block
deinterleaver 54 and the group-wise deinterleaver 55 may
be integrally formed.
[0522]
<LDPC decoding>
[0523] The LDPC decoding performed by the LDPC decoder
166 in Fig. 188 is further described.
[0524] The LDPC decoder 166 in Fig. 118 performs the
LDPC decoding of the LDPC code to which the block
deinterleave and the group-wide deinterleave are applied
and the parity interleave is not applied from the group-
wise deinterleaver 55 using the conversion parity check
matrix obtained by at least applying the column
permutation corresponding to the parity interleave to the
parity check matrix H used by the LDPC encoder 115 in Fig.
8 in the LDPC encoding as described above.
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[0525] Herein, the LDPC decoding capable of limiting
an operation frequency within a sufficiently feasible
range while limiting a circuit size by performing the
LDPC decoding using the conversion parity check matrix is
conventionally suggested (refer to Patent No. 4224777,
for example).
[0526] Firstly, the LDPC decoding using the conversion
parity check matrix conventionally suggested is first
described with reference to Fig. 121 to Fig. 124.
[0527] Fig. 121 illustrates an example of the parity
check matrix H of the LDPC code whose code length N is 90
and code rate is 2/3.
[0528] In Fig. 121 (also in Fig. 122 and Fig. 123 to
be described later), 0 is represented by a period (.).
[0529] In the parity check matrix H in Fig. 121, the
parity matrix has the stepwise structure.
[0530] Fig. 122 illustrates a parity check matrix H'
obtained by applying the row permutation in equation (11)
and the column permutation in equation (12) to the parity
check matrix H in Fig. 121.
[0531]
Row permutation: 6s + t + first row -> t + s + first row
(11)
[0532]
Column permutation: 6x + y + 61th row -> 5y + x + 61th
row (12)
[0533] In equations (11) and (12), s, t, x, and y are
integers within a range satisfying 0 s < 5, 0 t < 6,
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0 ._. x < 5, and 0 __ t < 6, respectively.
[0534] According to the row permutation in equation
(11), it is permutated such that 1st, 7th, 13th, 19th,
' and 25th rows, which leave a remainder of 1 when divided
by 6, are made 1st, 2nd, 3rd, 4th, and 5th rows, and 2nd,
8th, 14th, 20th, and 26th rows, which leave a remainder
of 2 when divided by 6, are made 6th, 7th, 8th, 9th, and
10th rows, respectively.
[0535] Also, according to the column permutation in
equation (12), it is permutated such that 61st, 67th,
73rd, 79th, and 85th columns, which leave a remainder of
1 when divided by 6, are made 61st, 62nd, 63rd, 64th, and
65th columns, and 62nd, 68th, 74th, 80th, and 86th
columns, which leave a remainder of 2 when divided by 6,
are made 66th, 67th, 68th, 69th, and 70th columns,
respectively, for the 61st and subsequent columns (parity
matrix).
[0536] The matrix obtained by performing the row
permutation and the column permutation of the parity
check matrix H in Fig. 121 in this manner is the parity
check matrix H' in Fig. 1222.
[0537] Herein, the row permutation of the parity check
matrix H does not affect the arrangement of the code bits
of the LDPC code.
[0538] The column permutation in equation (12)
corresponds to the parity interleave when the information
length K, the number of columns P being the unit of the
cyclic structure, and the submultiple q (= M/P) of the
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parity length M (herein, 30) of the above-described
parity interleave to interleave the K + qx + y + 1-th
code bit to the position of the K + Py + x + 1-th code
bit are set to 60, 5, and 6, respectively.
[0539] Accordingly, the parity check matrix H' in Fig.
122 is the conversion parity check matrix obtained by at
least applying the column permutation that the K + qx + y
+ 1-th column is permutated with the K + Py + x + 1-th
column of the parity check matrix H in Fig. 121
(hereinafter, appropriately referred to as the original
parity check matrix).
[0540] By multiplying the parity check matrix H' in
Fig. 122 by the LDPC code of the parity check matrix H in
Fig. 121 to which the same permutation as equation (12)
is applied, a 0 vector is output. That is to say, when a
row vector obtained by applying the column permutation in
equation (12) to the row vector c as the LDPC code (one
code word) of the original parity check matrix H is
represented as c', HcT becomes the 0 vector from the
nature of the parity check matrix, so that H'c'T naturally
becomes the 0 vector.
[0541] From above, the conversion parity check matrix
H' in Fig. 122 is the parity check matrix of the LDPC
code c' obtained by applying the column permutation in
equation (12) to the LDPC code c of the original parity
check matrix H.
[0542] Therefore, by applying the column permutation
in equation (12) to the LDPC code c of the original
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parity check matrix H, decoding (LDPC decoding) the LDPC
code c' after the column permutation using the conversion
parity check matrix H' in Fig. 122, and applying inverse
permutation in the column permutation in equation (12) to
the decoding result, it is possible to obtain the
decoding result similar to that in a case in which the
LDPC code of the original parity check matrix H is
decoded using the parity check matrix H.
[0543] Fig. 123 shows the conversion parity check
matrix H' in Fig. 122 with an interval between the units
of 5 x 5 matrix.
[0544] In Fig. 123, the conversion parity check matrix
H' is represented by a combination of the 5 x 5 (= P x P)
unit matrix, a matrix in which one or more 1 of the unit
matrix is set to 0 (hereinafter, appropriately referred
to as a quasi-unit matrix), a matrix obtained by the
cyclic shift of the unit matrix or the quasi-unit matrix
(hereinafter, appropriately referred to as a shift
matrix), a sum of two or more of the unit matrix, the
quasi-unit matrix, and the shift matrix (hereinafter,
appropriately referred to as a sum matrix), and a 5 x 5 0
matrix.
[0545] It may be said that the conversion parity check
matrix H' in Fig. 123 is configured of the 5 x 5 unit
matrix, quasi-unit matrix, shift matrix, sum matrix, and
0 matrix. Therefore, the 5 x 5 matrices (the unit matrix,
the quasi-unit matrix, the shift matrix, the sum matrix,
and the 0 matrix) constitute the conversion parity check
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matrix H' are hereinafter appropriately referred to as
constitutive matrices. '
[0546] An architecture to simultaneously perform P
check node operations and P variable node operations may
be used to decode the LDPC code of the parity check
matrix represented byaPxPconstitutive matrix.
[0547] Fig. 124 is a block diagram showing a
configuration example of the decoding device, which
performs such decoding.
[0548] That is to say, Fig. 124 shows the
configuration example of the decoding device, which
decodes the LDPC code using the conversion parity check
matrix H' in Fig. 123 obtained by at least applying the
column permutation in equation (12) to the original
parity check matrix H in Fig. 121.
[0549] The decoding device in Fig. 124 is configured
of an edge data storage memory 300 configured of 6 FIFOs
3001 to 3006, a selector 301, which selects from the FIFOs
3001 to 3006, a check node calculation unit 302, two
cyclic shift circuits 303 and 308, an edge data storage
memory 304 configured of 18 FIFOs 3041 to 30418, a
selector 305, which selects from the FIFOs 3041 to 30418,
a received data memory 306, which stores received data, a
variable node calculation unit 307, a decoded word
calculation unit 309, a received data rearrangement unit
310, and a decoded data rearrangement unit 311.
[0550] A method of storing the data in the edge data
storage memories 300 and 304 is first described.
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[0551] The edge data storage memory 300 is configured
of six FIFOs 3001 to 3006, the number of which is obtained
by dividing the number of rows 30 of the conversion
parity check matrix H' in Fig. 123 by the number of rows
(the number of columns P being the unit of the cyclic
structure) 5 of the constitutive matrix. The FIFOs 300y
(y = 1, 2, ..., 6) are formed of a plurality of stages of
storage regions and messages corresponding to five edges,
the number of which is equal to the number of rows and
the number of columns of the constitutive matrix (the
number of columns P being the unit of the cyclic
structure), may be read and written at the same time from
and to the storage region of each stage. The number of
stages of the storage regions of the FIFO 300y is set to
nine being a maximum number of 1 in the row direction of
the conversion parity check matrix in Fig. 123 (Hamming
weight).
[0552] The data corresponding to the position of 1
from first to fifth rows of the conversion parity check
matrix H' in Fig. 123 (a message vi from the variable
node) is stored in the FIFO 3001 in a form closed up in a
horizontal direction for each row (ignoring 0). That is
to say, when the j-th row i-th column is represented as
(j, i), the data corresponding to the position of 1 of
the 5 x 5 unit matrix from (1, 1) to (5, 5) of the
conversion parity check matrix H' is stored in the
storage region of a first stage of the FIFO 3001. The
data corresponding to the position of 1 of the shift
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matrix from (1, 21) to (5, 25) of the conversion parity
check matrix H' (shift matrix obtained by the cyclic
shift of the 5 x 5 unit matrix by three rightward) is
stored in the storage region of a second stage. The data
is similarly stored in the storage regions of third to
eighth stages in association with the conversion parity
check matrix H'. Then, the data corresponding to the
position of 1 of the shift matrix (shift matrix obtained
by replacement of 1 in the first row of the 5 x 5 unit
matrix with 0 and the cyclic shift thereof by one
leftward) from (1, 86) to (5, 90) of the conversion
parity check matrix H' is stored in the storage region of
a ninth stage.
[0553] The data corresponding to the position of 1
from 6th to 10th rows of the conversion parity check
matrix H' in Fig. 123 is stored in the FIFO 3002. That is
to say, the data corresponding to the position of 1 of a
first shift matrix configuring the sum matrix from (6, 1)
to (10, 5) of the conversion parity check matrix H' (the
sum matrix obtained by summing the first shift matrix
obtained by the cyclic shift of the 5 x 5 unit matrix by
one rightward and a second shift matrix obtained by the
cyclic shift thereof by two rightward) is stored in the
storage region of a first stage of the FIFO 3002. The
data corresponding to the position of 1 of the second
shift matrix configuring the sum matrix from (6, 1) to
(10, 5) of the conversion parity check matrix H' is
stored in the storage region of a second stage.
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[0554] That is to say, as for the constitutive matrix
whose weight is 2 or larger, the data corresponding to
the position of 1 of the unit matrix, the quasi-unit
matrix, and the shift matrix whose weight is 1 (message
corresponding to the edge belonging to the unit matrix,
the quasi-unit matrix, or the shift matrix) when the
constitutive matrix is represented as the sum of a
plurality of the P x P unit matrix whose weight is 1, the
quasi-unit matrix in which one or more of the elements 1
of the unit matrix is set to 0, and the shift matrix
obtained by the cyclic shift of the unit matrix or the
quasi-unit matrix is stored in the same address (same
FIFO out of the FIFOs 3001 to 3006)=
[0555] The data is hereinafter stored in association
with the conversion parity check matrix H' also in the
storage regions of third to ninth stages.
[0556] The data is stored in association with the
conversion parity check matrix H' also in the FIFOs 3003
to 3006.
[0557] The edge data storage memory 304 is configured
of 18 FIFOs 3041 to 30418, the number of which is obtained
by dividing the number of columns 90 of the conversion
parity check matrix H' by the number of columns 5 of the
constitutive matrix (the number of columns P being the
unit of the cyclic structure). The FIFO 304x (x = 1,
2, ..., 18) is formed of a plurality of stages of storage
regions, and the messages corresponding to the five edges,
the number of which is the number of rows and the number
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of columns of the constitutive matrix (the number of
columns P being the unit of the cyclic structure) may be
simultaneously read and written from and to the storage
region of each stage.
[0558] In the FIFO 3041, the data corresponding to the
position of 1 from first to fifth columns of the
conversion parity check matrix H' in Fig. 123 (message uj
from the check node) is stored in a form closed up in a
vertical direction for each column (ignoring 0). That is
to say, the data corresponding to the position of 1 of
the 5 x 5 unit matrix from (1, 1) to (5, 5) of the
conversion parity check matrix H' is stored in the
storage region of a first stage of the FIFO 3041. The
data corresponding to the position of 1 of the first
shift matrix configuring the sum matrix from (6, 1) to
(10, 5) of the conversion parity check matrix H' (the sum
matrix obtained by summing the first shift matrix
obtained by the cyclic shift of the 5 x 5 unit matrix by
one rightward and the second shift matrix obtained by the
cyclic shift thereof by two rightward) is stored in the
storage region of the second stage. The data
corresponding to the position of 1 of a second shift
matrix configuring the sum matrix from (6, 1) to (10, 5)
of the conversion parity check matrix H' is stored in the
storage region of a third stage.
[0559] That is to say, as for the constitutive matrix
whose weight is 2 or larger, the data corresponding to
the position of 1 of the unit matrix, the quasi-unit
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matrix, and the shift matrix whose weight is 1 (the
message corresponding to the edge belonging to the unit
matrix, the quasi-unit matrix, or the shift matrix) when
the constitutive matrix is represented as the sum of a
plurality of the P x P unit matrix whose weight is 1, the
quasi-unit matrix in which one or more of the elements 1
of the unit matrix is set to 0, and the shift matrix
obtained by the cyclic shift of the unit matrix or the
quasi-unit matrix is stored in the same address (same
FIFO out of the FIFOs 3041 to 304n)=
[0560] Hereinafter, the data is stored in the storage
regions of fourth and fifth stages in association with
the conversion parity check matrix H'. The number of
stages of the storage regions of the FIFO 3041 is five
being the maximum number of the number of 1 in the row
direction from the first to fifth columns of the
conversion parity check matrix H' (Hamming weight).
[0561] The data is similarly stored in association
with the conversion parity check matrix H' in the FIFOs
3042 and 3043, the length (the number of stages) of which
is five. The data is similarly stored in association with
the conversion parity check matrix H' in the FIFOs 3044 to
30412, the length of which is three. The data is similarly
stored in association with the conversion parity check
matrix H' in the FIFOs 30413 to 30418, the length of which
is two.
[0562] Next, operation of the decoding device in Fig.
124 is described.
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[0563] The edge data storage memory 300 is configured
of the six FIFOs 3001 to 3006, selects the FIFO in which
the data is stored from the FIFOs 3001 to 3006 according
to information (matrix data) D312 indicating the row of
the conversion parity check matrix H' in Fig. 123 to
which five messages D311 supplied from the cyclic shift
circuit 308 in a preceding stage belong, and collectively
stores the five messages D311 in the selected FIFO in
sequence. When reading the data, the edge data storage
memory 300 reads five messages D3001 from the FIFO 3001 in
sequence to supply to the selector 301 in a subsequent
stage. The edge data storage memory 300 reads the message
also from the FIFOs 3002 to 3006 in sequence after
finishing reading the message from the FIFO 3001 to supply
to the selector 301.
[0564] The selector 301 selects the five messages from
the FIFO from which the data is currently read out of the
FIFOs 3001 to 3006 according to a select signal D301 and
supplies the same as a message D302 to the check node
calculation unit 302.
[0565] The check node calculation unit 302 configured
of five check node calculators 3021 to 3025 performs the
check node operation according to equation (7) using the
messages D302 (D3021 to D3025) supplied through the
selector 301 (message vi in equation (7)) and supplies
five messages D303 (D3031 to D3035) obtained as a result
of the check node operation (message uj in equation (7))
to the cyclic shift circuit 303.
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[0566] The cyclic shift circuit 303 performs the
cyclic shift of the five messages D3031 to D3035 obtained
by the check node calculation unit 302 based on
information (matrix data) D305 indicating the value by
which the cyclic shift of the original unit matrix (or
the quasi-unit matrix) in the conversion parity check
matrix H' is performed to obtain the corresponding edge
and supplies a result to the edge data storage memory 304
as a message D304.
[0567] The edge data storage memory 304 is configured
of 18 FIFOs 3041 to 30418, selects the FIFO in which the
data is stored from the FIFOs 3041 to 30418 according to
the information D305 indicating the row of the conversion
parity check matrix H' to which the five messages D304
supplied from the cyclic shift circuit 303 in the
preceding stage belongs, and collectively stores the five
messages D304 in the selected FIFO in sequence. When
reading the data, the edge data storage memory 304 reads
the five messages D3061 in sequence from the FIFO 3041 to
supply to the selector 305 in the subsequent stage. The
edge data storage memory 304 reads the message in
sequence also from the FIFOs 3042 to 30418 after finishing
reading the data from the FIFO 3041 to supply to the
selector 305.
[0568] The selector 305 selects the five messages from
the FIFO from which the data is currently read out of the
FIFOs 3041 to 30418 according to a select signal D307 and
supplies the same to the variable node calculation unit
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307 and the decoded word calculation unit 309 as a
message D308.
[0569] On the other hand, the received data
rearrangement unit 310 rearranges an LDPC code D313
received through the communication channel 13
corresponding to the parity check matrix H in Fig. 121 by
the column permutation in equation (12) and supplies the
same to the received data memory 306 as received data
D314. The received data memory 306 calculates a received
LLR (log likelihood ratio) from the received data D314
supplied from the received data rearrangement unit 310 to
store and collectively supplies the five received LLRs to
the variable node calculation unit 307 and the decoded
word calculation unit 309 as received value D309.
[0570] The variable node calculation unit 307 is
configured of five variable node calculators 3071 to 3075,
performs the variable node operation according to
equation (1) using the messages D308 (D3081 to D3085)
supplied through the selector 305 (message uj in equation
(1) and the five received values D309 supplied from the
received data memory 306 (received value uoi in equation
(1)) and supplies messages D310 (D3101 to D3105) obtained
as a result of the operation (message vi in equation (1))
to the cyclic shift circuit 308.
[0571] The cyclic shift circuit 308 performs the
cyclic shift of the messages D3101 to D3105 calculated by
the variable node calculation unit 307 based on the
information indicating the value by which the cyclic
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shift of the original unit matrix (or the quasi-unit
matrix) in the conversion parity check matrix H' is
performed to obtain the corresponding edge and supplies a
result to the edge data storage memory 300 as a message
D311.
[0572] Single decoding (variable node operation and
check node operation) of the LDPC code may be performed
by single round of the above-described operation. The
decoding device in Fig. 124 decodes the LDPC code a
predetermined number of times, and then obtains a final
decoding result by the decoded word calculation unit 309
and the decoded data rearrangement unit 311 to output.
[0573] That is to say, the decoded word calculation
unit 309 is configured of five decoded word calculators
3091 to 3095, calculates the decoding result (decoded
word) based on equation (5) as a final stage of a
plurality of times of decoding using the five messages
D308 (D3081 to D3085) (message uj in equation (5)) output
by the selector 305 and the five received values D309
(received value un in equation (5)) supplied from the
received data memory 306, and supplies decoded data D315
obtained as a result to the decoded data rearrangement
unit 311.
[0574] The decoded data rearrangement unit 311 applies
the inverse permutation of the column permutation in
equation (12) to the decoded data D315 supplied from the
decoded word calculation unit 309, thereby rearranging an
order thereof and outputs the same as a final decoded
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result D316.
[0575] As described above, by applying any one or both
of the row permutation and the column permutation to the
parity check matrix (original parity check matrix) and
converting the same to the parity check matrix
(conversion parity check matrix) represented by the
combination of the P x P unit matrix, the quasi-unit
matrix in which one or more of the elements of 1 of the
unit matrix is set to 0, the shift matrix obtained by the
cyclic shift of the unit matrix or the quasi-unit matrix,
the sum matrix obtained by summing a plurality of the
unit matrix, the quasi-unit matrix, and the shift matrix,
and the P x P 0 matrix, that is to say, the combination
of the constitutive matrices, it becomes possible to
adopt the architecture to simultaneously perform the P
check node operations and the P variable node operations
as the decoding of the LDPC code where P is fewer than
the numbers of the columns and rows in the parity. When
it adopts the architecture to simultaneously perform the
P check node operations and the P variable node
operations as the decoding of the LDPC code where P is
fewer than the numbers of the columns and rows in the
parity check matrix, the operation frequency may be
limited within the feasible range to perform a great
number of times of repetitive decoding, as compared to a
case that the node operations are performed at the same
time for the same numbers of the numbers of the columns
and rows in the parity check matrix.
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[0576] The LDPC decoder 166, which configures the
receiving device 12 in Fig. 118, performs the LDPC
decoding by simultaneously performing the P check node
operations and the P variable node operations as is the
case with the decoding device in Fig. 124.
[0577] That is to say, in order to simplify the
description, supposing that the parity check matrix of
the LDPC code output by the LDPC encoder 115 configuring
the transmitting device 11 in Fig. 8 is the parity check
matrix H in which the parity matrix has the stepwise
structure illustrated in Fig. 121, for example, the
parity interleaver 23 of the transmitting device 11
performs the parity interleave to interleave the K + qx +
y + 1-th code bit to the position of the K + Py + x + 1-
th code bit by setting the information length K, the
number of columns being the unit of the cyclic structure,
and the submultiple q (= M/P) of the parity length M to
60, 5, and 6, respectively.
[0578] The parity interleave corresponds to the column
permutation in equation (12) as described above, so that
the LDPC decoder 166 is not required to perform the
column permutation in equation (12).
[0579] Therefore, in the receiving device 12 in Fig.
118, as described above, the LDPC code to which the
parity deinterleave is not applied, that is to say, the
LDPC code in a state in which the column permutation in
equation (12) is performed is supplied from the column
twist deinterleaver 55 to the LDPC decoder 166, and the
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LDPC decoder 166 performs the process similar to that of
the decoding device in Fig. 124 except that this does not
perform the column permutation in equation (12).
[0580] That is to say, Fig. 125 shows a configuration
example of the LDPC decoder 166 in Fig. 118.
[0581] In Fig. 125, the LDPC decoder 166 is configured
as the decoding device in Fig. 124 except that the
received data rearrangement unit 310 in Fig. 124 is not
provided, and this performs the process similar to that
of the decoding device in Fig. 124 except that the column
permutation in equation (12) is not performed, so that
the description thereof is omitted.
[0582] As described above, the LDPC decoder 166 may be
configured without the received data rearrangement unit
310, so that a scale thereof may be made smaller than
that of the decoding device in Fig. 124.
[0583] Although the code length N in the LDPC code,
the information length K, the number of columns (the
number of rows and the number of columns of the
constitutive matrix) being the unit of the cyclic
structure P, and the submultiple q (= M/P) of the parity
length M in the LDPC code are set to 90, 60, 5, and 6,
respectively, in Fig. 121 to Fig. 125 in order to
simplify the description, the code length N, the
information length K, the number of columns P being the
unit of the cyclic structure, and the submultiple q (=
M/P) are not limited to the above-described values.
[0584] That is to say, in the transmitting device 11
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in Fig. 8, the LDPC encoder 115 outputs the LDPC code of
the code length N of 64800, 16200 and the like, the
information length K of N - Pq (= N - M), the number of
columns P being the unit of the cyclic structure of 360,
and the submultiple q of M/P, for example, the LDPC
decoder 166 in Fig. 125 may also be applied to a case in
which the LDPC decoding is performed by simultaneously
performing the P check node operations and the P variable
node operations to such LDPC code.
[0585]
<Block diagram showing configuration example of block
deinterleaver 54>
[0586] Fig. 126 is a block diagram showing a
configuration example of a block deinterleaver 54.
[0587] The block deinterleaver 54 is configured
similar to the block deinterleaver 25 illustrated in Fig.
106.
[0588] The block deinterleaver 54 has a storage region
called as Part 1 and a storage region called as Part 2.
The Parts 1 and 2 store one bit in a row direction. The
number C of columns that are the storage regions for
storing the predetermined number of bits in a column
direction are arranged. The number C is equal to the
number of bits m of the symbols.
[0589] The block deinterleaver 54 preforms the block
deinterleave to the parts 1 and 2 by writing and reading
the LDPC code.
[0590] In the block deinterleave, the LDPC code (as
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the symbol) is written in an order that the block
interleaver in Fig. 106 reads the LDPC code.
[0591] Further, in the block deinterleave, the LDPC
code is read in an order that the block interleaver 25 in
Fig. 106 writes the LDPC code.
[0592] That is to say, in the block interleave by the
block interleaver 25 in Fig. 106, the LDPC code is
written to the parts 1 and 2 in the column direction and
is read in the row direction. In the block deinterleave
by the block deinterleaver 54 in Fig. 126, the LDPC code
is written to the parts 1 and 2 in the row direction and
is read in the column direction.
[0593]
<Another configuration example of bit deinterleaver 165>
[0594] Fig. 127 is a block diagram illustrating
another configuration example of the bit deinterleaver
165 in Fig. 118.
[0595] In the drawing, the same reference numeral is
assigned to a part corresponding to that in Fig. 119 and
the description thereof is hereinafter appropriately
omitted.
[0596] That is to say, the bit deinterleaver 165 in
Fig. 127 is configured in the same manner as that in Fig.
119 except that a parity deinterleaver 1011 is newly
provided.
[0597] In Fig. 127, the bit deinterleaver 165 is
configured of the block deinterleaver 54, the group-wise
deinterleaver 55, and the parity deinterleaver 1011 and
=
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performs the bit deinterleave of the code bit of the LDPC
code from the demapper 164.
[0598] That is to say, the block deinterleaver 54
performs the block deinterleave (inverse process of the
block interleave) corresponding to the block interleave
performed by the block interleaver 25 of the transmitting
device 11 for the LDPC code from the demapper 164, i.e.,
the block deinterleave to return the position of the code
bit interchanged by the block interleave to the original
position, and supplies the LDPC code obtained as a result
to the group-wise deinterleaver 55.
[0599] The group-wise deinterleaver 55 applies the
group-wise deinterleave corresponding to the group-wise
interleave as the rearranging process performed by the
group-wise interleaver 24 of the transmitting device 11
to the LDPC code from the block deinterleaver 54.
[0600] The LDPC code obtained as a result of the
group-wise deinterleave is supplied from the group-wise
deinterleaver 55 to the parity deinterleaver 1011.
[0601] The parity deinterleaver 1011 applies the
parity deinterleave (inverse process of the parity
interleave) corresponding to the parity interleave
performed by the parity interleaver 23 of the
transmitting device 11, that is to say, the parity
deinterleave to return the code bit of the LDPC code, the
arrangement of which is changed by the parity interleave,
to the original arrangement for the code bit after the
group-wise deinterleave by the group-wise deinterleaver
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55.
[0602] The LDPC code obtained as a result of the
parity deinterleave is supplied from the parity
deinterleaver 1011 to the LDPC decoder 166.
[0603] Therefore, in the bit deinterleaver 165 in Fig.
127, the LDPC code to which the block deinterleave, the
group-wise deinterleave, and the parity deinterleave are
applied, that is to say, the LDPC code obtained by the
LDPC encoding according to the parity check matrix H is
supplied to the LDPC decoder 166.
[0604] The LDPC decoder 166 performs the LDPC decoding
of the LDPC code from the bit deinterleaver 165 using the
parity check matrix H used by the LDPC encoder 115 of the
transmitting device 11. That is to say, the LDPC decoder
166 performs the LDPC decoding of the LDPC code from the
bit deinterleaver 165 using the parity check matrix H
itself used by the LDPC encoder 115 of the transmitting
device 11 in the LDPC encoding or the conversion parity
check matrix obtained by at least applying the column
permutation corresponding to the parity interleave to the
parity check matrix H.
[0605] Herein, in Fig. 127, since the LDPC code
obtained by the LDPC encoding according to the parity
check matrix H is supplied from (the parity deinterleaver
1011 of) the bit deinterleaver 165 to the LDPC decoder
166, the LDPC decoder 166 may be configured of the
decoding device, which performs the LDPC decoding by a
full serial decoding scheme to sequentially perform the
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operation of the message (check node message and the
variable node message) one node after another, and the
decoding device, which performs the LDPC decoding by a
full parallel decoding scheme to simultaneously perform
the operation of the message (in parallel) for all the
nodes, for example, when the LDPC decoding of the LDPC
code is performed using the parity check matrix H itself
used by the LDPC encoder 115 of the transmitting device
11 in the LDPC encoding.
[0606] Also, when the LDPC decoder 166 performs the
LDPC decoding of the LDPC code using the conversion
parity check matrix obtained by at least performing the
column permutation corresponding to the parity interleave
of the parity check matrix H used by the LDPC encoder 115
of the transmitting device 11 in the LDPC encoding, the
LDPC decoder 166 may be configured of the decoding device
of the architecture to simultaneously perform the P (or
submultiple of P other than 1) check node operations and
variable node operations being the decoding device (Fig.
124) including the received data rearrangement unit 310
to rearrange the code bits of the LDPC code by applying
the column permutation similar to the column permutation
for obtaining the conversion parity check matrix to the
LDPC code.
[0607] Although the block deinterleaver 54, which
performs the block deinterleave, the group-wise
deinterleaver 55, which performs the group-wise
deinterleave, and the parity deinterleaver 1011, which
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performs the parity deinterleave, are separately formed
for convenience of description in Fig. 127, two or more
of the block deinterleaver 54, the group-wise
deinterleaver 55, and the parity deinterleaver 1011 may
be integrally formed as the parity interleaver 23, the
group-wise interleaver 24, and the block interleaver 25
of the transmitting device 11.
[0608]
<Configuration example of receiving system>
[0609] Fig. 128 is a block diagram showing a first
configuration example of a receiving system to which the
receiving device 12 may be applied.
[0610] In Fig. 128, the receiving system is configured
of an obtaining unit 1101, a transmission channel
decoding processor 1102, and an information source
decoding processor 1103.
[0611] The obtaining unit 1101 obtains a signal
including the LDPC code obtained by at least the LDPC
encoding of the LDPC target data such as the image data
and the audio data of the program through a transmission
channel (communication channel) (not shown) such as
digital terrestrial broadcasting, digital satellite
broadcasting, and a network such as a CATV network, the
Internet and the like, for example, to supply to the
transmission channel decoding processor 1102.
[0612] Herein, if the signal obtained by the obtaining
unit 1101 is broadcasted from a broadcasting station
through the terrestrial wave, a satellite wave, the CATV
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(cable television) network and the like, for example, the
obtaining unit 1101 is configured of a tuner, an STB (set
top box) and the like. When the signal obtained by the
obtaining unit 1101 is multicast-transmitted from a web
server such as IPTV (Internet protocol television), for
example, the obtaining unit 1101 is configured of a
network I/F (interface) such as an NIC (network interface
card), for example.
[0613] The transmission channel decoding processor
1102 corresponds to the receiving device 12. The
transmission channel decoding processor 1102 applies a
transmission channel decoding process at least including
a process to correct the error occurring in the
transmission channel to the signal obtained by the
obtaining unit 1101 through the transmission channel and
supplies the signal obtained as a result to the
information source decoding processor 1103.
[0614] That is to say, the signal obtained by the
obtaining unit 1101 through the transmission channel is
the signal obtained by at least the error correction
encoding for correcting the error occurring in the
transmission channel and the transmission channel
decoding processor 1102 applies the transmission channel
decoding process such as an error correction process, for
example, to such signal.
[0615] Herein, the error correction encoding includes
the LDPC encoding, BCH encoding and the like, for example.
Herein, the LDPC encoding is at least performed as the
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error correction encoding.
[0616] Also, the transmission channel decoding process
may include demodulation of a modulated signal and the
like.
[0617] The information source decoding processor 1103
applies an information source decoding process at least
including a process to expand compressed information to
original information to the signal to which the
transmission channel decoding process is applied.
[0618] That is to say, there is a case in which
compression encoding to compress the information is
applied to the signal obtained by the obtaining unit 1101
through the transmission channel so as to decrease a data
volume of the image and the audio as the information, and
in this case, the information source decoding processor
1103 applies the information source decoding process such
as the process to expand the compressed information to
the original information (expanding process) to the
signal to which the transmission channel decoding process
is applied.
[0619] If the compression encoding is not applied to
the signal obtained by the obtaining unit 1101 through
the transmission channel, the information source decoding
processor 1103 does not perform the process to expand the
compressed information to the original information.
[0620] Herein, the expanding process includes MPEG
decoding and the like, for example. Also, the
transmission channel decoding process might include
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descrambling and the like in addition to the expanding
process.
[0621] In the receiving system configured as above,
the obtaining unit 1101 applies the compression encoding
such as MPEG encoding to the data of the image and the
audio, for example, and obtains the signal to which the
error correction encoding such as the LDPC encoding is
applied through the transmission channel to supply to the
transmission channel decoding processor 1102.
[0622] The transmission channel decoding processor
1102 applies the process similar to that performed by the
receiving device 12 and the like to the signal from the
obtaining unit 1101 as the transmission channel decoding
process, for example, and the signal obtained as a result
is supplied to the information source decoding processor
1103.
[0623] The information source decoding processor 1103
applies the information source decoding process such as
the MPEG decoding to the signal from the transmission
channel decoding processor 1102 and outputs the image or
the audio obtained as a result.
[0624] The receiving system in Fig. 128 as described
above may be applied to a television tuner and the like,
which receives television broadcasting as the digital
broadcasting, for example.
[0625] It is possible to form each of the obtaining
unit 1101, the transmission channel decoding processor
1102, and the information source decoding processor 1103
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as one independent device (hardware (IC (integrated
circuit) and the like) or a software module).
[0626] Also, as for the obtaining unit 1101, the
transmission channel decoding processor 1102, and the
information source decoding processor 1103, it is
possible to form a set of the obtaining unit 1101 and the
transmission channel decoding processor 1102, a set of
the transmission channel decoding processor 1102 and the
information source decoding processor 1103, and a set of
the obtaining unit 1101, the transmission channel
decoding processor 1102, and the information source
decoding processor 1103 as one independent device.
[0627] Fig. 129 is a block diagram illustrating a
second configuration example of the receiving system to
which the receiving device 12 may be applied.
[0628] Meanwhile, in the drawing, the same reference
numeral is assigned to a part corresponding to that in
Fig. 128 and the description thereof is hereinafter
appropriately omitted.
[0629] The receiving system in Fig. 129 is the same as
that in Fig. 128 in that this includes the obtaining unit
1101, the transmission channel decoding processor 1102,
and the information source decoding processor 1103 and is
different from that in Fig. 128 in that an output unit
1111 is newly provided.
[0630] The output unit 1111 is a display device, which
displays the image, and a speaker, which outputs the
audio, for example, and this outputs the image, the audio
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and the like as the signal output from the information
source decoding processor 1103. That is to say, the
output unit 1111 displays the image or outputs the audio.
[0631] The receiving system in Fig. 129 as described
above may be applied to a TV (television receiver), which
receives the television broadcasting as the digital
broadcasting, a radio receiver, which receives radio
broadcasting, and the like, for example.
[0632] If the compression encoding is not applied to
the signal obtained by the obtaining unit 1101, the
signal output by the transmission channel decoding
processor 1102 is supplied to the output unit 1111.
[0633] Fig. 130 is a block diagram showing a third
configuration example of the receiving system to which
the receiving device 12 may be applied.
[0634] In the drawing, the same reference numeral is
assigned to a part corresponding to that in Fig. 128 and
the description thereof is hereinafter appropriately
omitted.
[0635] The receiving system in Fig. 130 is the same as
that in Fig. 128 in that this includes the obtaining unit
1101 and the transmission channel decoding processor 1102.
[0636] However, the receiving system in Fig. 130 is
different from that in Fig. 128 in that the information
source decoding processor 1103 is not provided and a
record unit 1121 is newly provided.
[0637] The record unit 1121 records (stores) the
signal output from the transmission channel decoding
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processor 1102 (for example, a TS packet of MPEG TS) in a
recording (storage) medium such as an optical disk, a
hard disk (magnetic disk), and a flash memory.
[0638] The receiving system in Fig. 130 as described
above may be applied to a recorder and the like, which
records the television broadcasting.
[0639] In Fig. 130, the receiving system may be
provided with the information source decoding processor
1103 and the information source decoding processor 1103
may record the signal to which the information source
decoding process is applied, that is to say, the image
and the audio obtained by the decoding in the record unit
1121.
[0640]
[One embodiment of computer]
[0641] A series of processes described above may be
performed by hardware or by software. When a series of
processes is performed by the software, a program, which
configures the software, is installed on a multi-purpose
computer and the like.
[0642] Fig. 131 shows a configuration example of one
embodiment of the computer on which the program, which
executes a series of processes described above, is
installed.
[0643] The program may be recorded in advance in a
hard disk 705 and a ROM 703 as a recording medium stored
in the computer.
[0644] Alternatively, the program may be temporarily
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or permanently stored (recorded) in a removable recording
medium 711 such as a flexible disk, a CD-ROM (compact
disc read only memory), an MO (magnetooptical) disk, a
DVD (digital versatile disc), the magnetic disk, and a
semiconductor memory. Such removable recording medium 711
may be provided as so-called packaged software.
[0645] In addition to installation from the above-
described removable recording medium 711 on the computer,
the program may be transferred from a downloading site to
the computer by wireless through a satellite for the
digital satellite broadcasting or transferred to the
computer by wire through the network such as a LAN (local
area network) and the Internet, and the computer may
receive the program transferred in this manner by a
communication unit 708 to install on an internal hard
disk 705.
[0646] The computer has a CPU (central processing
unit) 702 built-in. An input/output interface 710 is
connected to the CPU 702 through a bus 701 and, when an
instruction is input through the input/output interface
710 by operation and the like of the input unit 707
configured of a keyboard, a mouse, a microphone and the
like by a user, the CPU 702 executes the program stored
in the ROM (read only memory) 703 according to the same.
Alternatively, the CPU 702 loads the program stored in
the hard disk 705, the program transferred from the
satellite or the network to be received by the
communication unit 708 and installed on the hard disk 705,
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or the program read from the removable recording medium
711 mounted on a drive 709 to be installed on the hard
disk 705 on a RAM (random access memory) 704 to execute.
According to this, the CPU 702 performs the process
according to the above-described flowchart or the process
performed by the configuration of the above-described
block diagram. Then, the CPU 702 outputs a processing
result from an output unit 706 configured of an LCD
(liquid crystal display), a speaker and the like, or
transmits the same from the communication unit 708, or
records the same in the hard disk 705 through the
input/output interface 710, for example, as needed.
[0647] Herein, in this specification, a processing
step to write the program to allow the computer to
perform various processes is not necessarily required to
be processed in chronological order along order described
in the flowchart and this also includes the process
executed in parallel or individually executed (for
example, a parallel process or a process by an object).
[0648] Also, the program may be processed by one
computer or distributedly processed by a plurality of
computers. Further, the program may be transferred to a
remote computer to be executed.
[0649] The embodiment of the present technology is not
limited to the above-described embodiment and various
modifications may be made without departing from the
scope of the present technology.
[0650] For example, (the parity check matrix initial
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value table of) the above-described new LDPC code may be
through the communication channel 13 (Fig. 7), any of
which is a satellite circuit, a terrestrial wave, and a
cable (wire circuit). Furthermore, the new LDPC code may
be used for data transmission other than the digital
broadcasting.
[0651] The above-described GW patterns may be applied
to any other than the new LDPC code. Furthermore, the
modulation scheme to which the above-described GW
patterns are applied is not limited to 16QAM, 64QAM,
256QAM and 1024QAM.
[0652] Effects described herein are not limited only
to be illustrative, there may be effects other than those
described herein.
Description of reference numerals
[0653]
11 transmitting device
12 receiving device
23 parity interleave
24 group-wise interleaver
block interleaver
31 memory
32 interchange unit
25 54 block deinterleaver
55 group-wise interleaver
111 mode adaptation/multiplexer
112 padder
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113 BB scrambler
114 BCH encoder
115 LDPC encoder
116 bit interleaver
117 mapper
118 time interleaver
119 SISO/MISO encoder
120 frequency interleaver
121 BCH encoder
122 LDPC encoder
123 mapper
124 frequency interleaver
131 frame builder & resource allocation
132 OFDM generation
151 OFDM processor
152 frame management
153 frequency deinterleaver
154 demapper
155 LDPC decoder
156 BCH decoder
161 frequency deinterleaver
162 SISO/MISO decoder
163 time deinterleaver
164 demapper
165 bit deinterleaver
166 LDPC decoder
167 BCH decoder
168 BB descrambler
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169 null deletion
170 demultiplexer
300 edge data storage memory
301 selector
302 check node calculation unit
303 cyclic shift circuit
304 edge data storage memory
305 selector
306 received data memory
307 variable node calculation unit
308 cyclic shift circuit
309 decoded word calculation unit
310 received data rearrangement unit
311 decoded data rearrangement unit
601 encoding processor
602 storage unit
611 code rate set unit
612 initial value table read unit
613 parity check matrix generation unit
614 information bit read unit
615 encoding parity operation unit
616 controller
701 bus
702 CPU
703 ROM
704 RAM
705 hard disk
70 output unit
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707 input unit
708 communication unit
709 drive
710 input/output interface
711 removable recording medium
1001 inverse interchange unit
1002 memory
1011 parity deinterleaver
1101 obtaining unit
1101 transmitting channel decoding processor
1103 information source decoding processor
1111 output unit
1121 record unit
