CA 02651608 2008-11-06
WO 2007/133022 PCT/KR2007/002342
Description
APPARATUS AND METHOD FOR PROVIDING RELAY LINK
ZONE INFORMATION IN A MULTI-HOP RELAY
BROADBAND WIRELESS ACCESS COMMUNICATION
SYSTEM
Technical Field
[1] The present invention generally relates to a multi-hop relay Broadband
Wireless
Access (BWA) communication system, and in particular, to an apparatus and
method
for providing information about a relay link zone in which information to be
relayed to
a Mobile Station (MS) is sent.
Background Art
[21 Providing services with diverse Quality of Service (QoS) requirements at
or above
100Mbps to users is an active study area for a future-generation communication
system
called a 4th Generation (4G) communication system. In particular, active
research is
being conducted on providing high-speed service by ensuring mobility and QoS
to a
BWA communication system, such as Wireless Local Area Network (WLAN)
systems, Wireless Metropolitan Area Network (WMAN) systems, etc. Such major
examples comply with Institute of Electrical and Electronics Engineers (IEEE)
802.16d and IEEE 802.16e standards.
[31 IEEE 802.16d and IEEE 802.16e communication systems are implemented by
applying Orthogonal Frequency Division Multiplexing (OFDM)/Orthogonal
Frequency Division Multiple Access (OFDMA) to physical channels. IEEE 802.16d
considers only a single-cell structure with no regard to mobility of
Subscriber Stations
(SSs). In contrast, IEEE 802.16e supports mobility of SSs to the IEEE 802.16d
com-
munication system. A mobile SS is referred to below as an MS.
[41 FIG. 1 shows a conventional IEEE 802.16e communication system configured
in a
multi-cell structure. The system shown in FIG. 1 includes cells 100 and 150,
BSs 110
and 140 for managing the cells 100 and 150, respectively, and a plurality of
MSs 111,
113, 130, 151 and 153. Signaling is carried out in OFDM/OFDMA between the BSs
110 and 140 and the MSs 111, 113, 130, 151 and 153. The MS 130 exists in a
cell
boundary area between the cells 100 and 150, i.e. in a handover region. When
the MS
130 moves to the cell 150 managed by the BS 140 during signal
transmission/reception
to/from the BS 110, the serving BS of the MS 130 changes from the BS 110 to
the BS
140.
[51 Since signaling in FIG. 1 is performed between an MS and a fixed BS via a
direct
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link, a highly reliable radio communication link can be established between
them in the
conventional IEEE 802.16e communication system. However, due to the fixedness
of
BSs, a wireless network cannot be configured with flexibility. As a result,
the IEEE
802.16e communication system is not effective in efficiently providing
communication
services under a radio environment experiencing a fluctuating traffic
distribution and a
great change in the number of calls.
[61 The above problem can be solved by applying a multi-hop relay data
transmission
scheme using fixed Relay Stations (RSs), mobile RSs, or general MSs to general
cellular wireless communication systems, such as IEEE 802.16e. A multi-hop
relay
wireless communication system can advantageously reconfigure a network rapidly
according to a communication environmental change and enables efficient
operation of
the whole wireless network. For example, a multi-hop relay wireless
communication
system can expand cell coverage and increase system capacity. When the channel
status between a BS and an MS is bad, an RS can be installed between them so
the
resulting establishment of a multi-hop relay path through the RS renders a
higher-
speed radio channel available to the MS. With the use of a multi-hop relay
scheme at a
cell boundary offering a bad channel status, high-speed data channels can be
provided
and the cell coverage can be expanded.
[71 Now a description will be made of the configuration of the multi-hop relay
wireless
communication system which expands cell coverage of BSs.
[81 FIG. 2 shows a conventional multi-hop relay BWA communication system
configured to expand the cell coverage of BSs. The multi-hop relay BWA com-
munication system, which is configured in a multi-cell structure, includes
cells 200 and
240, BSs 210 and 250 for managing the cells 200 and 240, respectively, a
plurality of
MSs 211 and 213 within the coverage area of the cell 200, a plurality of MSs
221 and
223 managed by the BS 210 but located in an area 230 outside the cell 200, an
RS 220
for providing multi-hop relay paths between the BS 210 and the MSs 221 and 223
within the area 230, a plurality of MSs 251, 253 and 255 within the coverage
area of
the cell 240, a plurality of MSs 261 and 263 managed by the BS 250 but located
in an
area 270 outside the cell 240, and an RS 260 for providing multi-hop relay
paths
between the BS 250 and the MSs 261 and 263 within the area 270.OFDM/OFDMA
signals are exchanged among the BSs 210 and 250, the RSs 220 and 260, and the
MSs
211, 213, 221, 223, 251, 253, 255, 261 and 263.
[91 Although the MSs 211 and 213 within the coverage area of the cell 200 and
the RS
220 can communicate directly with the BS 210, the MSs 221 and 223 within the
area
230 cannot communicate with the BS 210 directly. Therefore, the RS 220
covering the
area 230 relays signals between the BS 210 and the MSs 211 and 223. Meanwhile,
although the MSs 251, 253 and 255 within the coverage area of the cell 240,
and the
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RS 260 can communicate directly with the BS 250, the MSs 261 and 263 within
the
area 270 cannot communicate with the BS 250, directly. Therefore, the RS 260
covering the area 270 relays signals between the BS 250 and the MSs 261 and
263.
[101 In the multi-hop relay BWA communication system shown in FIG. 2, the RSs
220
and 260 are infrastructure RSs installed by service providers and are thus
known to the
BSs 210, 240 and 310, or client RSs acting as SSs or MSs, or as RSs under cir-
cumstances. The RSs 220 and 260 may also be fixed, nomadic (e.g. laptop), or
mobile
like MSs.
[ill To expand cell coverage by use of an RS as described above, a
conventional frame
structure defined for communications between a BS and an MS should be extended
to
enable communications among a BS, an MS and an RS. In other words, a frame
structure should be defined, which enables a BS to communicate with a
plurality of
RSs and MSs based on a single communication platform. To do so, a DownLink
(DL)
frame from the BS should be divided into a BS-MS communication zone and a BS-
RS
communication zone and an UpLink (UL) frame to the BS should be divided into
an
MS-BS communication zone and an RS-BS communication zone. That is, the RSs
should be accommodated through appropriate division of limited resources.
However,
considering that the number of RSs connected to the BS and the channel
environment
are time-variant, i.e. the cell environment is very variable, it is
inefficient to fix the BS-
RS communication zone or the RS-BS communication zone. In this context,
techniques for dynamically operating these zones have recently been proposed.
Ac-
cordingly, a need exists for defining a signaling procedure for providing
information
about the zones to an RS.
Disclosure of Invention
Technical Solution
[121 The present invention substantially solves at least the above-described
problems and/
or disadvantages and provides at least the advantages below. Accordingly, an
aspect of
the present invention is to provide an apparatus and method for providing an
RS with
information about a relay link zone for communications between a BS and the RS
in a
multi-hop relay BWA communication system.
[131 Another aspect of the present invention is to provide an apparatus and
method for
providing information about a relay link zone to an RS during initial access
of the RS
to a BS in a multi-hop relay BWA communication system.
[141 A further aspect of the present invention is to provide an apparatus and
method for,
when a change occurs in size of a relay link zone in which communications are
conducted between a BS and an RS, providing information about the size change
to the
RS in a multi-hop relay BWA communication system.
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[151 Still another aspect of the present invention is to provide an apparatus
and method
for, when a mobile RS performs a handover, providing the RS with information
about
a relay link zone for communications between the RS and a target BS in a multi-
hop
relay BWA communication system.
[161 According to an aspect of the present invention, there is provided a
communication
method for a BS in a multi-hop relay cellular communication system, in which
the BS
performs a network entry procedure with an RS during an initial access of the
RS to
the BS, generates a message including relay link zone information regarding a
relay
link zone in which the BS communicates with the RS, processes the message in a
physical layer, and transmits the processed message to the RS.
[171 According to another aspect of the present invention, there is provided a
com-
munication method for a BS in a multi-hop relay cellular communication system,
in
which the BS determines whether to change a relay link zone in which the BS
com-
municates with an RS, generates a message including relay link zone change in-
formation when the BS determines to change the relay link zone, processes the
message in a physical layer, and broadcasts the processed message to RSs.
[181 According to a further aspect of the present invention, there is provided
a com-
munication method for a BS in a multi-hop relay cellular communication system,
in
which the BS receives relay link zone information regarding a target BS from
the
target BS, when an RS performs a handover, generates a message including the
relay
link zone information regarding the target BS, processes the message in a
physical
layer, and transmits the processed message to the RS.
[191 According to still another aspect of the present invention, there is
provided a com-
munication method for an RS in a multi-hop relay cellular communication
system, in
which the RS performs a network entry procedure with a BS during an initial
access to
the BS, receives a message including relay link zone information about a relay
link
zone for communications between the RS and the BS, and performs an RS
operation in
the relay link zone indicated by the relay link zone information.
[201 According to yet another aspect of the present invention, there is
provided a com-
munication method for an RS in a multi-hop relay cellular communication
system, in
which the RS monitors reception of a message including relay link zone change
in-
formation about a relay link zone for communications between the BS and the
RS,
detects a changed relay link zone from the message, upon receipt of the
message, and
performs an RS operation in a relay link zone indicated by the relay link zone
change
information.
[211 According to still a further aspect of the present invention, there is
provided a com-
munication method for an RS in a multi-hop relay cellular communication
system, in
which the RS receives a message including relay link zone information
regarding a
CA 02651608 2011-11-17
target BS, when the RS performs a handover, detects a relay link zone for
communications between the RS and the target BS from the received message, and
performs an RS operation in the relay link zone after the handover.
According to an aspect of the present invention, there is provided a
communication
method for a Base Station (BS) in a multi-hop relay cellular communication
system, the
communication method comprising:
performing a network entry procedure with a Relay Station (RS) during an
initial
access of the RS to the BS;
generating a message including relay link zone information regarding a relay
link
zone in which the BS communicates with the RS;
processing the message in a physical layer; and
transmitting the processed message to the RS,
wherein the message includes a relay zone indicator indicating whether the
relay
link zone information is included.
According to another aspect of the present invention, there is provided a
communication
method for a Base Station (BS) in a multi-hop relay cellular communication
system, the
communication method comprising:
performing a network entry procedure with a Relay Station (RS) during an
initial
access of the RS to the BS;
generating a message including relay link zone information regarding a relay
link
zone in which the BS communicates with the RS;
processing the message in a physical layer; and
transmitting the processed message to the RS,
wherein the message includes a relay zone indicator indicating whether one of
a
Gap and a Peak-to-Average Power Ratio (PAPR) reduction region is allocated.
According to a further aspect of the present invention, there is provided a
communication method for a Base Station (BS) in a multi-hop relay cellular
communication system, the communication method comprising:
determining whether to change a relay link zone in which the BS communicates
with a Relay Station (RS);
generating a message including relay link zone change information when the BS
determines to change the relay link zone, wherein the message includes
information
indicating a start of a relay link zone in a next frame;
processing the message in a physical layer; and
broadcasting the processed message to RSs.
According to a further aspect of the present invention, there is provided a
communication method for a Base Station (BS) in a multi-hop relay cellular
communication system, the communication method comprising:
receiving relay link zone information defining a relay link zone of a frame
CA 02651608 2011-11-17
5a
through which a target BS communicates with a Relay Station (RS) from the
target BS,
when the RS performs a handover;
generating a message including the relay link zone information regarding the
target BS; and
processing the message in a physical layer and transmitting the processed
message to the RS.
According to a further aspect of the present invention, there is provided a
communication method for a Relay Station (RS) in a multi-hop relay cellular
communication system, the communication method comprising:
performing a network entry procedure with a Base Station (BS) during an
initial
access to the BS;
receiving a message including relay link zone information about a relay link
zone
for communications between the RS and the BS; and
performing an RS operation in the relay link zone indicated by the relay link
zone
information,
wherein the message includes a relay zone indicator indicating whether the
relay
link zone information is included.
According to a further aspect of the present invention, there is provided a
communication method for a Relay Station (RS) in a multi-hop relay cellular
communication system, the communication method comprising:
performing a network entry procedure with a Base Station (13S) during an
initial
access to the BS;
receiving a message including relay link zone information about a relay link
zone
for communications between the RS and the BS; and
performing an RS operation in the relay link zone indicated by the relay link
zone
information,
wherein the message includes a relay zone indicator indicating whether one of
a
Gap and a Peak-to-Average Power Ratio (PAPR) reduction region is allocated.
According to a further aspect of the present invention, there is provided a
communication method for a Relay Station (RS) in a multi-hop relay cellular
communication system, the communication method comprising:
monitoring reception of a message including relay link zone change information
about a relay link zone for communications between the BS and the RS, wherein
the
message includes information indicating a start of a relay link zone in a next
frame;
detecting a changed relay link zone from the message, upon receipt of the
message; and
performing an RS operation in a relay link zone indicated by the relay link
zone
change information.
According to a further aspect of the present invention, there is provided a
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Sb
communication method for a Relay Station (RS) in a multi-hop relay cellular
communication system, the communication method comprising:
receiving a message including relay link zone information defining a relay
link
zone of a frame through which a target Base Station (BS) communicates with the
RS,
when the RS performs a handover;
detecting a relay link zone for communications between the RS and the target
BS
from the received message; and
performing an RS operation in the relay link zone after the handover.
According to a further aspect of the present invention, there is provided a
communication method in a multi-hop relay cellular communication system, the
communication method comprising:
transmitting a first message including relay link zone information to a Relay
Station (RS) by a Base Station (BS) during an initial access of the RS to the
BS;
detecting the relay link zone information from the first message by the RS;
and
performing an RS operation in a relay link zone indicated by the relay link
zone
information by the RS,
wherein the first message includes a relay zone indicator indicating whether
the
relay link zone information is included.
According to a further aspect of the present invention, there is provided a
communication method in a multi-hop relay cellular communication system, the
communication method comprising:
transmitting a first message including relay link zone information to a Relay
Station (RS) by a Base Station (BS) during an initial access of the RS to the
BS;
detecting the relay link zone information from the first message by the RS;
and
performing an RS operation in a relay link zone indicated by the relay link
zone
information by the RS,
wherein the message includes a relay zone indicator indicating whether one of
a
Gap and a Peak-to-Average Power Ratio (PAPR) reduction region is allocated.
According to a further aspect of the present invention, there is provided an
apparatus of
a Base Station (BS) in a multi-hop relay cellular communication system, the
apparatus
comprising:
a message generator for generating a first message including relay link zone
information about a relay link zone for communications between the BS and a
Relay
Station (RS); and
a transmitter for processing the first message in a physical layer and
transmitting
the processed message to the RS during an initial access of the RS,
wherein the first message includes a relay zone indicator indicating whether
the
relay link zone information is included.
According to a further aspect of the present invention, there is provided an
apparatus of
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Sc
a Base Station (BS) in a multi-hop relay cellular communication system, the
apparatus
comprising:
a message generator for generating a first message including relay link zone
information about a relay link zone for communications between the BS and a
Relay
Station (RS); and
a transmitter for processing the first message in a physical layer and
transmitting
the processed message to the RS during an initial access of the RS,
wherein the message includes a relay zone indicator indicating whether one of
a
Gap and a Peak-to-Average Power Ratio (PAPR) reduction region is allocated.
According to a further aspect of the present invention, there is provided an
apparatus of
a Relay Station (RS) in a multi-hop relay cellular communication system, the
apparatus
comprising:
a controller for receiving a first message including relay link zone
information
about a relay link zone for communications between the RS and a Base Station
(BS)
during an initial access to the BS and controlling a transceiver to perform an
RS
operation in the relay link zone indicated by the relay link zone information;
and
the transceiver for communicating with the BS in the relay link zone,
wherein the first message includes a relay zone indicator indicating whether
the
relay link zone information is included.
According to a further aspect of the present invention, there is provided an
apparatus of
a Relay Station (RS) in a multi-hop relay cellular communication system, the
apparatus
comprising:
a controller for receiving a first message including relay link zone
information
about a relay link zone for communications between the RS and a Base Station
(BS)
during an initial access to the BS and controlling a transceiver to perform an
RS
operation in the relay link zone indicated by the relay link zone information;
and
the transceiver for communicating with the BS in the relay link zone,
wherein the first message includes a relay zone indicator indicating whether
one
of a Gap and a Peak-to-Average Power Ratio (PAPR) reduction region is
allocated.
Brief Description of the Drawings
[221 The above and other objects, features and advantages of the present
invention will
become more apparent from the following detailed description when taken in
conjunction with the accompanying drawings in which:
[23] FIG. I illustrates a conventional IEEE 802.16e communication system;
[24] FIG. 2 illustrates a conventional multi-hop relay BWA communication
system
configured to expand the cell coverage of BSs;
[251 FIG. 3 illustrates a frame structure for providing synchronized
synchronization
channels to MSs or RSs in a multi-hop relay BWA communication systems
according to
the present invention;
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Sd
[26] FIG. 4 is a flowchart illustrating an operation of a BS for providing
relay link zone
information to an RS in the multi-hop relay BWA communication systems
according to
the present invention;
[27] FIG. 5 is a flowchart illustrating an operation of an RS for receiving
relay link zone
information from a BS in the multi-hop relay BWA communication systems
according to
the present invention;
[28] FIG. 6 is a diagram illustrating a signal flow for providing relay link
zone information
regarding a target BS to an RS that performs a handover to the target BS in
the multi-hop
relay BWA communication systems according to the present invention; and
[29] FIG. 7 is a block diagram of a BS or an RS according to the present
invention.
Best Mode for Carrying Out the Invention
[30] Preferred embodiments of the present invention will be described herein
below with
reference to the accompanying drawings. In the following description, well-
known
functions or constructions are not described in detail since they would
obscure the
invention.
[311 The present invention discloses a signaling procedure for providing a
Relay Station
(RS) with information. about a relay link zone in which information to be
relayed to a
Mobile Station (MS) is sent in a multi-hop relay Broadband Wireless Access
(BWA)
communication system. The following description is made of a method for
providing
relay link zone information to an RS that initially accesses a Base Station
(BS) and a
method for, when a change occurs to size of the relay link zone, providing
information
about the size change to the RS. Further, when a mobile RS performs a handover
to a
target BS, a method for providing the RS with information about a relay link
zone for
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communications with the target BS is provided.
[321 The multi-hop relay BWA communication system operates in Orthogonal
Frequency
Division Multiplexing/Orthogonal Frequency Division Multiple Access
(OFDM/OFDMA). In view of the nature of OFDM/OFDMA that sends physical
channel signals on a plurality of subcarriers, the multi-hop relay BWA
communication
system is capable of high-speed data transmission and supports the mobility of
MSs.
[331 In the multi-hop relay BWA communication system, RSs are fixed or mobile
nodes,
or particular systems installed by BSs. Such a node serves as an RS through
relay
capability negotiations with a BS according to a preset criterion for cell
coverage
expansion.
[341 While the present invention is described in the context of a multi-
carrier BWA com-
munication system as an example,, the present invention may also be used with
any
cellular communication system using a multi-hop relay scheme.
[351 FIG. 3 shows a frame structure for providing synchronized synchronization
channels
to MSs or RSs in a multi-hop relay BWA communication systems according to the
present invention. A BS frame 300 is divided into a DownLink (DL) subframe 310
and
an UpLink (UL) subframe 320. The DL subframe 310 is configured to provide a
syn-
chronization channel to an MS in the form of a preamble, for synchronization
and cell
search at the MS, and to provide a synchronization channel to an RS in the
form of a
postamble, for synchronization and cell search at the RS. With the fixed syn-
chronization channels at the start and end of the DL subframe 310, the MS or
the RS
can acquire synchronization information and neighbor BS information.
[361 The DL subframe 310 is divided into time-multiplexed first and second
zones 311
and 313, and the UL subframe 320 is divided into time-multiplexed first and
second
zones 321 and 323. The lengths of the first and second zones 311, 321, 313 and
323
are fixed or dynamically changed according to cell environment.
[371 In the BS frame 300, a BS communicates with an MS connected to the BS via
a
direct link in the first zones 311 and 321 and communicates with an RS in the
second
zones 313 and 323. Because the first and second zones 311, 321, 313 and 323
may
vary in length according to the cell environment, the BS allocates the
synchronization
channels or ranging channels at the start of the first zones 311 and 321 and
at the end
of the second zones 313 and 323, thereby providing the synchronized
synchronization
channels to the MS and the RS. The ranging channels (or ranging slots) may
reside at
positions indicated by a control channel in the UL subframe 320, instead of
fixed
positions.
[381 In an RS frame 350, the RS communicates with an MS connected to the RS
via a
direct link in first zones 361 and 371. To provide a synchronized
synchronization
channel to the MS, the RS allocates the synchronization channel or a ranging
channel
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at the start of the first zones 361 and 371.
[391 As stated earlier, since the first zones 311 and 321 and the second zones
313 and 323
of the BS frame 300, and the first zones 361 and 371 of the RS frame 350 may
change
in length dynamically according to the cell environment, the BS should inform
the RS
of a change in the zone sizes. Accordingly, there exists a need for defining a
signaling
procedure for providing information about a change in the sizes of
communication
zones to the RS in the relay system using the frame structures shown in FIG.
3.
[401 FIG. 4 shows an operation of a BS for providing relay link zone
information to an RS
in the multi-hop relay BWA communication systems according to the present
invention. The BS performs an initial access operation (i.e. network entry)
with the RS
in the first zones 311 and 321 of the BS frame 300 shown in (A) of FIG. 3 in
step 401.
That is, a necessary DL message is sent to the RS in the first zone 311 of the
DL
subframe 310 and a necessary UL message is sent to the BS in the first zone
321 of the
UL subframe 320 during the initial access. When the RS is activated as a relay
after the
initial access, the BS communicates with the RS in relay link zones
corresponding to
the second zones 313 and 323 of the BS frame 300. In the mean time, the RS com-
municates with an MS in the first zones 361 and 371 of the RS frame 360.
[411 After the initial access, the BS sends to the RS information about the
relay link zone,
i.e. the second zone 313 of the DL subframe 310 of the BS frame 300 in step
403.
[421 The relay link zone information can be delivered by System Time Clock
(STC)_DL_ZONE_IE designed to indicate a zone using a specific permutation or a
specific transmit diversity mode. The STC_DL_ZONE_IE is configured as follows
in
Table 1 below.
[431 Table 1
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[Table 11
Table 1
Syntax Size Notes
(bits)
STC_DL_ZONE_IEO {
Extended DIUC 4 STC/DL ZONE SWITCH=OxOl
Length 4 Length=0x04
OFDMA symbol offset 8 Denotes the start of zone (counting from the
frame preamble and starting from 0)
Permutation 2 ObOO=PUSC permutation
ObO 1=FUSC permutation
OblO=Optional FUSC permutation
Obi 1=Optional adjacent subcarrier
permutation
Use All SC indicator 1 0=do not use all subchannels
f=use all subchannels
STC 2 ObOO=no STC
ObOl=STC using 2/3 antennas
Ob 10=STC using 4 antennas
Ob11=FHDC using 2 antennas
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[44] Matrix indicator 2 STC matrix
If (STC=ObO I or STC==Ob 10)
{
0b00=Matrix A
ObO1=Matrix B
Ob1O=Matrix C
Ob 11=reserved
}
else if (STC=Obl 1)
{
ObOO=Matrix A
ObO 1 =Matrix B
OblO-11=reserved
}
DL_PermBase 5
PRBS ID 2 Value: 0..2
AMC type 2 Indicates the AMC type in case permutation
type=Ob11, otherwise shall be set to 0.
AMC type (NxM=N bits by M symbols)
ObOO=1x6
ObOl=2x3
0b10=3x2
Obi 1=reserved
note that only 2x3 Band AMC subchannel
type (AMC type=ObOI) is supported by MS
Midamble presence 1 0=not present
1=present at the first symbol in STC zone
[451 Midamble boosting 1 O=no boost
1=boosting (3dB)
2/3 antennas select 1 O=STC using 2 antennas
l=STC using 3 antennas
selects 2/3 antennas when STC=ObO1
Dedicated pilots 1 O=pilot symbols are broadcast
1=pilot symbols are dedicated. An MS
should use only pilots specific to its burst
for channel estimation
RS DL zone indicator 1 Indicates the RS DL zone
Reserved 3 Shall be set to zero
}
[461 In Table 1, STC_DL_ZONE_IE includes OFDMA symbol offset indicating the
start
of the zone indicated by the Information Element (IE), Permutation indicating
a
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permutation type used for the zone, and RS DL zone indicator indicating that
the zone
is a relay link zone.
[471 Aside from the use of 1 bit as the RS DL zone indicator in the
STC_DL_ZONE_IE
shown in Table 1, a conventional message or a new message can be used to
deliver the
relay link zone information in step 403. For instance, the 1-bit RS DL zone
indicator
can be included in AAS_DL_IE designed to indicate an Adaptive Antenna System
(AAS) zone. The AAS_DL_IE has the following configuration.
[481 Table 2
[Table 21
Table 2
Syntax Size (bits) Notes
Downlink preamble 2 ObOO=O symbols
coding ObOl=1 symbol
OblO=2 symbols
Ob11=3 symbols
Preamble type 1 0-Frequency shifted preamble is used in this
DL AAS zone
1 -Time shifted preamble is used in this DL
AAS zone
PRBS ID 2 Refer to 8.4.9.4.1
RS DL zone indicator 1 Indicates the RS DL zone
}
[491 To send the relay link zone information to the RS, an RS DL zone
indicator may be
included in a Frame Control Header (FCH) and a relay link zone may be
indicated by a
Generic Access Protocol (GAP)/Peak-to-Average Power Ratio (PAPR) reduction IE
that specifies a GAP/PAPR reduction region. In this case, the FCH contains the
following information shown in Table 3 below.
[501 Table 3
[Table 31
Table 3
RS DL zone indicator 1 bit Indicates the RS DL zone
[511 Upon receipt of the FCH with RS DL zone indicator, the RS determines that
a zone
indicated by GAP/PAPR reduction IE in a DL-MAP is a relay link zone and
operates
as a relay in the relay link zone.
[521 The GAP/PAPR reduction IE may serve the original purpose other than
indicating th
e relay link zone. In this case, when a lower node (MS or RS) of the BS
receives a
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signal in the zone indicated by the GAP/PAPR reduction IE, the lower node can
neglect the signal. Hence, when the RS receives a plurality of GAP/PAPR
reduction
IEs from the BS or an upper RS, the RS should be able to distinguish a
GAP/PAPR
reduction IE that indicates a relay link zone from among the GAP/PAPR
reduction IEs.
To notify which GAP/PAPR reduction IE indicates the relay link zone, the RS DL
zone indicator in the FCH can be used. Then, the FCH may contain the following
RS
DL Zone Indicator.
[531 Table 4
[Table 41
Table 4
RS DL Zone indicator x bits Indicates the RS DL zone
[541 In Table 4, RS DL Zone indicator indicates that a GAP/PAPR reduction IE
is
included in the DL MAP and, when a plurality of GAP/PAPR reduction lEs are
included, the RS DL Zone indicator identifies a GAP/PAPR reduction IE
indicating the
relay link zone.
[551 For example, the RS DL Zone indicator occupies 2 bits and when the RS DL
Zone
indicator is set to 01, a first one of GAP/PAPR reduction lEs in the DL-MAP
indicates
the relay link zone. Therefore, upon receipt of an FCH with the RS DL Zone
indicator
of 01, the RS determines that the first GAP/PAPR reduction IE in the DL-MAP
indicates the relay link zone and operates as a relay in the indicated relay
link zone.
[561 While it has been described above that the RS DL zone indicator of the
FCH and the
GAP/PAPR reduction IE are used to indicate a relay link zone in the next
frame, they
may also be used to indicate a relay link zone in a second next, a third next,
or any
other following frame. A frame in which an indicated relay link zone resides
can be
indicated by a system initialization value or system information. The frame
may be
fixed or changed during system operation. In the latter case, the BS notifies
its lower
nodes of the change by system information or the like.
[571 Meanwhile, when an MS receives the GAP/PAPR reduction IE with the relay
link
zone information, the MS considers that a zone indicated by the GAP/PAPR
reduction
IE is not valid for the MS.
[581 In step 405, the BS determines whether to change a size of the relay link
zone cor-
responding to the second zone 313 of the DL subframe 310 for the next frame.
The B S
maintains the current relay link zone in step 407 when the BS determines not
to change
the size of the relay link zone. The BS sends relay link zone change
information to the
RS in step 409 when the BS determines to change the size of the relay link
zone.
[591 A message notifying of the relay link zone change in the next frame is
configured as
follows in Table 5 below.
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[601 Table 5
[Table 51
Table 5
Syntax Size Notes
(bits)
DL_Frame_Prefix() {
used subchannel bitmap 6 Bit #0: subchannel group 0
Bit #1: subchannel group 1
Bit #2: subchannel group 2
Bit #3: subchannel group 3
Bit #4: subchannel group 4
Bit #5: subchannel group 5
2 Ob00: no repetition coding on DL-MAP
repetition_coding_indication ObOl: repetition coding of 2 used on DL-
MAP
OblO: repetition coding of 4 used on DL-
MAP
Obll: repetition coding of 6 used on DL-
MAP
[611
coding_indication 3 Ob000: CC encoding used on DL-MAP
ObOOl: BTC encoding used on DL-MAP
ObO10: CTC encoding used on DL-MAP
ObOll: ZT CC encoding used on DL-
MAP
OblOO: CC encoding with optional
interleaver
OblOl: LDPC encoding used on DL-
MAP
Ob11O-Oblll:reserved
DL-MAP length 8
OFDMA symbol offset 5 Ob00000: no change
ObOxxxx: xxx symbols increase
Oblxxxx: xxx symbols decrease
}
[621 Referring to Table 5, the relay link zone change notification message
called
DL_Frame_Prefix is included in an FCH that the BS sends to the RS in the relay
link
zone. DL_Frame_Prefix contains used subchannel bitmap indicating a subchannel
group to be used in the next frame, repetition-coding-indication indicating a
repetition
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coding for a DL-MAP following DL_Frame_Prefix, coding-indication indicating a
coding scheme for the DL-MAP, DL-MAP length indicating the length of the DL-
MAP, and OFDMA symbol offset (or OFDMA symbol index) indicating the start of
the relay link zone in the next frame. OFDMA symbol offset may notify whether
the
start offset is changed and how much the start offset is increased/decreased.
For
example, given an OFDMA symbol offset=0b00000, the OFDMA symbol offset
implies that the start offset of the relay link zone is not changed in the
next frame.
When an OFDMA symbol offset=ObOxxxx, the OFDMA symbol offset implies that the
start offset of the relay link zone is increased by xxxx symbols in the next
frame. When
an OFDMA symbol offset=0blxxxx, the OFDMA symbol offset implies that the start
offset of the relay link zone is decreased by xxxx symbols in the next frame.
The
OFDMA symbol offset can be set according to a link variation. Besides the
sequential
increase/decrease described in Table 5, the increase/decrease may happen in a
pattern
specifying an exponential or linear increase/decrease.
[631 As an example of Table 5, the relay link zone change information about
the next
frame can be sent to the RS by a DL-MAP message in the relay link zone of the
current
frame. Table 6 below shows an RS_DL-MAP message with the relay link zone
change
information.
[641 Table 6
[Table 61
Table 6
Syntax Size Notes
(bits)
RS DL MAP format() {
Compressed map indicator 2 Set to binary 11
Reserved 1 Shall be set to zero
RS UL MAP appended 1 Indicates that RS UL MAP follows
RS DL MAP
Next RS DL zone change 1 Indicates whether the RS DL zone is
indicator changed in next frame
MAP message length 10
OFDMA PHY 32 Frame duration code (8 bits), Frame
synchronization field number (24 bits)
DCD count 8
Operator ID 8
Sector ID 8
No. OFDMA symbol 8 Number of OFDMA symbols in RS
DL subframe including all
permutation zone
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[65] DL IE count 8
For (i=0; i<DL IE count;
i++) {
DL-MAP IEO Variable
}
If (Next RS DL zone change
indicator=l) {
OFDMA symbol offset 4 Oxxxx: xxxx symbols increase
lxxxx: xxxx symbols decrease
}
}
[661 In Table 6, the RS_DL-MAP message includes Compressed map indicator
indicating
that this message is a compressed MAP, RS UL MAP appended indicating whether
an
RS_UL-MAP message providing MAP information about the relay link zone 323 of
the UL subframe 320 of the BS frame 300 is present or not, Next RS DL zone
change
indicator indicating whether the start offset of the relay link zone changes
in the next
frame, OFDMA symbol offset indicating the increase/decrease of the start
offset of the
relay link zone in the next frame, MAP message length indicating the length of
the
RS_DL-MAP message, No. OFDMA symbol indicating the number of OFDMA
symbols in the relay link zone 313 of the DL subframe 310 in the BS frame 300,
and a
plurality of DL-MAP_IEs that provide MAP information about the relay link zone
313.
The value of the OFDMA symbol offset is set according to a link variation. The
increase/decrease of the start offset of the relay link zone in the next frame
can be
performed in a pattern specifying an exponential or linear increase/decrease
other than
a sequential increase/decrease.
[671 In the presence of the RS UL MAP that provides MAP information about the
relay
link zone 323 of the UL subframe 320 in the BS frame 300 in Table 6, the
RS_UL-MAP has the following configuration.
[681 Table 7
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[Table 71
Table 7
Syntax Size Notes
(bits)
RS UL MAP format() {
UCD count 8
Allocation start time 32
No. OFDMA symbols 8 Number of OFDMA symbols in the
RS UL subframe
while (map data remains) {
UL-MAP_IEO Variable
}
If ! (byte boundary) {
padding nibble 4 Padding to reach byte boundary
}
[691 In Table 7, the RS_UL-MAP message contains UCD count indicating the count
of
Uplink Channel Descriptor (UCD) messages that include profile information
about
bursts sent in the relay link zone 323 of the UL subframe 320 in the BS frame
300,
Allocation start time indicating the allocation start time of the relay link
zone 323, No.
OFDMA symbols indicating the number of OFDMA symbols in the relay link zone
323, and a plurality of UL-MAP lEs that provide MAP information about the
relay link
zone 323.
[701 As described above, the relay link zone change information can be sent to
the RS in
the FCH message or the MAP message. Alternatively, the relay link zone change
in-
formation can be delivered on a newly defined message configured as follows.
[711 Table 8
[Table 81
Table 8
Syntax Size (bits) Notes
RS_DL zone_change_IE() {
Extended DIUC/Extended-2 4/8 BS-RS-DL-zone-change
DIUC
Length 4
OFDMA symbol offset 4 Oxxxx: xxxx symbols increase
lxxxx: xxxx symbols decrease
}
[721 In Table 8, RS_DL_zone_change_IE contains OFDMA symbol offset indicating
the
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size of an increased/decrease in the start offset of the relay link zone in
the next frame.
The OFDMA symbol offset is set to a value based on a pattern specifying an ex-
ponential or linear increase/decrease other than a sequential
increase/decrease.
[731 FIG. 5 shows an operation of an RS for receiving relay link zone
information from a
BS in the multi-hop relay BWA communication systems according to the present
invention. The RS initially accesses the BS in the first zones 311 and 321 of
the BS
frame 300 shown in (A) of FIG. 3 in step 501. The RS, which has been activated
as a
relay after the initial access, receives STC_DL_ZONE_IE shown in Table 1 from
the
BS and acquires relay link zone information about the DL relay link zone 313
of the
BS frame 300 from the STC_DL_ZONE_IE in step 503. Another way to acquire the
relay link zone information is to receive AAS_DL_IE including an RS DL zone
indicator from the BS. A third way to acquire the relay link zone information
is to
receive an FCH with an RS DL zone indicator and a DL MAP with a GAP/PAPR
reduction IE.
[741 In step 505, the RS receives a DL signal from the BS in a relay link zone
indicated
by the relay link zone information. Then the RS monitors reception of a relay
link zone
change message from the BS in step 507. The relay link zone change message can
be
DL_Frame_Prefix shown in Table 5, RS_DL-MAP shown in Table 6, or
RS_DL_zone_change_IE shown in Table 8.
[751 Upon receipt of the relay link zone change message, the RS acquires
information
about a changed relay link zone from the received message and performs an RS
operation in the changed relay link zone in step 509. If the RS does not
receive the
relay link zone change message, it performs an RS operation in the current
relay link
zone in step 511.
[761 With reference to FIGs. 4 and 5, the above description is made of the BS
that
performs an initial access operation with the RS and the RS that performs an
RS
operation after the initial access.
[771 If the RS is mobile, it should continue relaying signals to lower nodes
under its
control even when it moves from the serving BS to a target BS. Accordingly,
the RS
needs to have knowledge of a relay link zone of the target BS for
communications with
the target BS after the handover.
[781 FIG. 6 shows a signal flow for providing relay link zone information
regarding a
target BS to an RS that performs a handover to the target BS in the multi-hop
relay
BWA communication systems according to the present invention. A target BS 650
sends its relay link zone information to a serving BS 610 over a backbone
network in
step 611. The relay link zone information is configured as follows.
[791 Table 9
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[Table 91
Table 9
Name Size (bits) Notes
DL zone symbol 8 Denotes the start of RS DL zone (starting
offset from 0)
DL zone permutation 2 ObOO: PUSC permutation
ObOl: FUSC permutation
Ob 10: Optional FUS C permutation
0b 1l: Optional adjacent subcarrier
permutation
}
[801 In Table 9, the relay link zone information received from the target BS
contains DL
zone symbol offset indicating a first symbol of a DL relay link zone of the
target BS
and DL zone permutation indicating a permutation type applied to the DL relay
link
zone.
[811 In step 613, the serving BS 610 sends the relay link zone information
shown in Table
9 to an RS 640. The relay link zone information may be delivered in a Mobile
Neighbor Advertisement (MOB_NBR-ADV) message that the serving BS 610 sends to
provide neighbor BS information to the RS 640. Or the relay link zone
information
may be included in a handover request message that the BS sends to the RS in
order to
request a handover, or a handover response message that the BS sends to the RS
in
response to a handover request message received from the RS.
[821 The RS 640 notifies the serving BS 610 of a handover to the target BS 650
in step
615. In step 617, the serving BS 610 notifies the target BS 650 of the
handover of the
RS 640 by a handover notification message with the relay link zone information
regarding the target BS 650 known to the RS 640.
[831 Therefore, the target BS 650 keeps the relay link zone unchanged until
the handover
is completed in step 619. In the mean time, the RS 640 performs the handover
to the
target BS 650 in step 621 and continues serving as a relay in the service area
of the
target BS 650 using the relay link zone information of the target BS 650 in
step 623.
[841 The above description focuses on how to send information about relay link
zones
corresponding to the second zones 313 and 323, particularly the DL relay link
zone
313 in the BS frame 300 shown in (A) of FIG. 3. Information about the UL relay
link
zone 323 can be provided to the RS in an RS_UL-MAP message without the RS DL
zone indicator that exists in the STC DL ZONE IE of Table 1 or the AAS DL IE.
That is, the RS can acquire information about the UL relay link zone 323 for
every
frame, referring to Allocation start time and No. OFDMA symbols in the RS-UL-
MAP
message shown in Table 7.
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[851 An overall operation for sending/receiving information about relay link
zones
between a BS and an RS in the multi-hop relay BWA communication system has
been
described. Now a description will be made of the structure of the BS and the
RS for
sending/receiving the relay link zone information between them. The BS and the
RS
with the same interface module (i.e. communication module) have the same con-
figuration. Thus, the operations of the BS and the RS will be described in the
context
of a single device shown in FIG. 7. While the following description is made in
a Time
Division Duplex (TDD)-OFDMA system, it is to be clearly understood that the
present
invention is easily applicable to a Frequency Division Duplex (FDD)-OFDMA
system,
a hybrid TDD-FDD system, and other cellular systems using different resource
division schemes.
[861 FIG. 7 shows a BS or an RS according to the present invention. The BS (or
the RS)
includes a Radio Frequency (RF) processor 701, an Analog-to-Digital Converter
(ADC) 703, an OFDM demodulator 707, a message processor 709, a controller 711,
a
message generator 713, an encoder 715, an OFDM modulator 717, a Digital-to-
Analog
Converter (DAC) 719, an RF processor 721, a switch 723, and a timing
controller 725.
[871 The timing controller 725 controls the switching of the switch 723 based
on time
synchronization. For example, during a signal reception period, the timing
controller
725 controls the switch 723 to switch an antenna to the RF processor 701 at a
receiver
side. During a signal transmission period, the timing controller 725 controls
the switch
723 to switch the antenna to the RF processor 721 at a transmitter side.
[881 During the reception, the RF processor 701 downconverts an RF signal
received
through the antenna to an analog baseband signal. The ADC 703 converts the
analog
baseband signal to sample data. The OFDM demodulator 705 converts the sample
data
to frequency data by Fast Fourier Transform (FFT) and selectively outputs data
on
intended subcarriers from among the frequency data.
[891 The decoder 707 demodulates and decodes the OFDM-demodulated data
received
from the OFDM demodulator 705 at a Modulation and Coding Scheme (MCS) level.
[901 The message processor 709 analyzes a control message received from the
decoder
707 and provides the analysis result to the controller 711. The controller 711
ap-
propriately processes the information received from the message processor 709,
and
generates and provides transmission information to the message generator 713.
The
message generator 713 generates a message with the received information.
[911 The encoder 715 in a physical layer encodes and modulates the data
received from
the message generator 713 at an MCS level. The OFDM modulator 717 converts the
coded data to sample data (i.e. an OFDM symbol) by Inverse Fast Fourier
Transform
(IFFT). The DAC 719 converts the sample data to an analog signal. The RF
processor
721 upconverts the analog signal to an RF signal and sends the RF signal
through the
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antenna.
[921 The controller 711 is a protocol controller for controlling the message
processor 709
and the message generator 713. That is, the controller 711 can implement the
functions
of the message processor 709 and the message generator 713. While the message
processor 709 and the message generator 713 are shown separately for
describing their
functions distinguishably, their functions can be partially or wholly
incorporated into
the controller 711.
[931 The controller 711 receives necessary information from a function block
in the
physical layer or provides a control signal to a function block during
protocol
processing.
[941 Operations of the BS and the RS will be described in the context of the
configuration
shown in FIG. 7. The following description focuses on processing control
messages in
a Media Access Control (MAC) layer.
[951 During the BS operation, the controller 711 provides overall control in
relation to a
change in a relay link zone. After initial access by an RS, the controller 711
generates
information about a relay link zone of a BS DL subframe in which to
communicate
with the RS. The message generator 713 generates a message including the relay
link
zone information received from the controller 711 and provides the message to
the
physical layer. This message can be the zone switch message STC_DL_ZONE_IE
shown in Table 1, the AAS_DL_IE shown in Table 2, or a GAP/PAPR reduction IE.
When the GAP/PAPR reduction IE carries the relay link zone information, an FCH
message may have an RS DL zone indicator indicating that the GAP/PAPR
reduction
IE includes the relay link zone information.
[961 The controller 711 determines whether to change the relay link zone in
size. The
controller 711 generates relay link zone change information when the
controller 711 is
determining to change the relay link zone size. The message generator 713
generates a
message including the relay link zone change information received from the
controller
711 and provides the message to the physical layer. The message with the relay
link
zone change information is the FCH message shown in Table 5 sent from the BS
to the
RS in a current frame, the RS DL MAP message shown in Table 6, or the newly
defined message shown in Table 8.
[971 Upon receipt of a message with relay link zone information regarding a
target BS
(Table 9) to which a mobile RS performs a handover over a backbone network,
the
controller 711 extracts relay link zone information of the target BS from the
received
message. The message generator 713 generates a message including the relay
link zone
information of the target BS received from the controller 711 and provides the
relay
link zone information to the physical layer. This message can be a MOB_NBR-ADV
message designed to provide neighbor BS information to the RS, a handover
request
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message from the BS for requesting a BS-initiated handover, or a handover
response
message that the BS sends to the mobile RS in response to a handover request
message
received from the RS.
[981 The controller 711 also generates information about a UL relay link zone
in which
the BS communicates with the RS. The message generator 713 generates a message
including the UL relay link zone information received from the controller 711
and
provides it to the physical layer. This message can be the RS UL MAP message
shown
in Table 4.
[991 The messages generated from the message generator 713 are processed in
transmittable forms in the physical layer and sent through the antenna.
[1001 During the RS operation, the message processor 709 analyzes a control
message
received from an MS or the BS and provides the analysis result to the
controller 711.
Upon receipt of a message with DL relay link zone information (STC_DL_Zone_IE,
AAS_DL_IE, or GAP/PAPR reduction IE), or a message with DL relay link zone
change information (DL_Frame_prefix, RS DL MAP, or RS_DL_zone_change_IE)
from the BS according to the present invention, the message processor 709
extracts
control information from the received message.
[1011 The controller 711 determines a relay link zone in which to communicate
with the
BS based on the control information received from the message processor 711
and
provides overall control to the RS so the RS acts as a relay in
synchronization to the
relay link zone.
[1021 Upon receipt of a message with relay link zone information of a target
BS shown in
Table 9 from the serving BS during a handover, the message processor 709
extracts the
relay link zone information of the target BS from the received message. The
controller
711 determines a relay link zone in which to communicate with the target BS
based on
the control information received form the message processor 711 and provides
overall
control to the RS so the RS acts as a relay in synchronization to the relay
link zone of
the target BS after the handover.
[1031 As described above, the present invention provides a method for
providing an RS
with information about a relay link zone in which a BS communicates with the
RS in a
multi-hop relay BWA communication system. Because the relay link zone can be
changed within a limited frame dynamically according to a cell environment,
limited
resources are efficiently utilized.
[1041 While the invention has been shown and described with reference to
certain preferred
embodiments thereof, it will be understood by those skilled in the art that
various
changes in form and details may be made therein without departing from the
spirit and
scope of the invention as defined by the appended claims.
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