Note: Descriptions are shown in the official language in which they were submitted.
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LINE CARDS FOR WG, COIN, ISDN, AND SPECIAL SERVICES
Cross-References
This application claims the benefit of U.S.
Provisional Application No. 60/011,242 filed on
February 6 1996 entitled ~Hex and Quad Line Cards fo~
POTs, ISDN and coin services," of which Thomas R. Eames
is the inventor, ~ith attorney docket number P708.
This application is also related to US patent
application serial number filed
on even date herewith, entitled ~Method and Apparatus
for Reliable Operation of Universal Voice Grade Cards,"
of which Thomas ~. Eames, Lac X. Trinh, E. Barton
Manchester, Bradley N. Yearwood, David J. Manley, Scott
T. Hicks, Jaskarn S. Johal, and Charles A. Eldering are
the inventors, with attorney docket number M-4066, and
which describes the construction and operation of
Universal Voice Grade cards.
All of the aforementioned applications are
incorporated herein by this reference, but are not
admitted to be prior art.
Field Of The Invention
The present invention relates to a method and
apparatus for delivering Plain Old Telephony (POTs)
voice telecommunications services in combination with
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coin phone, Integrated Service Digital Network (ISDN)
and special services.
Bachyl~ul~d Of The Invention
Fiber-to-the-curb (FTTC) systems can provide both
traditional telecommunications services such as Plain
Old Telephony service (POTs), coin phone services,
Integrated Services Digital Network (ISDN) and special
telecommunications services as well as advanced
multimedia services such as Switched Diyital Video
(SDV) and high speed data access. Because o~ the range
of services which can be supported, it is likely that
FTTC systems will be widely deployed ~y telephone
companies as they install new lines and upgrade their
networks.
FTTC systems typically have equipment in the
central o~ice including a Host Digital Terminal (HDT)
which is connected by optical ~iber to an Optical
Network Unit (ONU), which can be located on a telephone
pole or in a pedestal in a neighborhood. For
traditional telecommunications services including POTs,
coin, ISDN and special services the ONU is connected to
subscriber residences by twisted copper pair wire. A
printed circuit board containing electronics and
~requently re~erred to as a channel unit or line card
is inserted into the ONU to provide telecommunications
services over the twisted copper pair. The ONU
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typically serves between 8 and 16 residences. Each
subscriber is provided service by a subscriber circuit
on a line card in the ONU
The majority of the subscribers require POTs
services which can be provided by a Universal Voice
Grade (WG) card. In addition to POTs, the WG card
can provide a number of other locally switched special
services which include Centrex Lines, Private Branch
Exchange (PBX) lines, and 800 number service lines.
The WG card cannot provide coin phone or IDSN services
without additional or substantially different
circuitry.
In addition to POTs, coin, and ISDN services,
there are a number of special locally switched, non-
locally switched, digital data, non-switched, DC alarm,
and low speed signaling services which a telephone
company may need to support, although they may be
required by a very small percentage of customers.
In any telephone service area there will be a
percentage of subscriber circuits which require either
ISDN or coin services. This percentage may be in the
range of 6-12~, although the demand for ISDN services
is presently growing, and could re~ult ln ~ penetrati3n
(as a percentage of homes served) for ISDN services
which reaches 25~.
Construction of an ONU is typically such that the
line cards (WG or otherwise) can be inserted into the
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ONU and made operational as additional lines are
required. To keep the manu~acturing costs o~ the ONU
as low as possible, it is common to integrate two, ~our
or six subscriber circuits on a line card. In the case
o~ W G cards this results in what are re~erred to as
dual, quad or hex WG line cards. It is also possible
that eight subscriber circuits could be integrated on a
line card resulting in a octal line card.
Because coin and ISDN services are an important
component o~ the services delivered by the ONU, it is
necessary to have line cards which can support these
services. One approach is to use a special line card
which provides one coinicircuit. Similarly, a special
card ~or ISDN services can be developed. Having a
single circuit on a card allows ~or the possibility o~
closely matching the percentage o~ coin or ISDN
circuits provided with the percentage o~ coin or I~DN
circuits required by inserting the appropriate nu~ber
o~ coin or ISDN cards in the ONU. The drawback with
this approach is that cards containing a single
subscriber circuit are not cost e~ective, due to the
~act that they do not share overhead circuitry with
other subscriber circuits, and occupy an entire slot in
the ONU.
A second approach to solving this problem is to
have a line card which contains ~our or six W G, coin,
or ISDN circuits. Since multiple identical circuits
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are on the same board, a cost savings over multiple
individual boards with the same circuit can be
realized, and the number of slots required in the ONU
- to serve a given number of subscribers is decreased
over that which would be found if dual or single
circuit cards are used. The drawback with this
approach is that it is difficult to match the
percentage of coin or ISDN circuits provided with the
percentage of coin or ISDN circuits required since
insertion of an ISDN or coin card results in four or
six coin or ISDN circuits.
A third approach, the requirements for which has
been outlined by Bellcore in their publication TR-TSY-
0003~8, entitled "Universal Digital Channel (UDC)
Generic Requirements and Objectives," is to use a card
which provides existing analog and digital service
capability including ISDN service. However, since this
card will contain additional circuitry over which is
~ound in a W G card, it will inherently be more costly
than a WG card. The aforementioned Bellcore
specification is incorporated herein by reference.
Even if these problems for coin phones and ISDN
lines are addressed, there is still the need to provide
special services, which will often require a line card
with special circuitry.
For the foregoing reasons, there is a need for
cost-effective line cards which provide ~or a close
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match between the number of coin and ISDN circuits
provided, with the number of coin and ISDN circuits
required. There i8 also the need for a method of
providing special services which does not result in an
engineering and cost penalty to the other type of
telecommunications circuits in high demand.
Summary Of The Invention
In the present invention a channel unit or line
card contains a circuit for Plain Old Telephony service
~POTs) and a circuit for a service such as Integrated
Services Digital Network (ISDN), coin (pay phone)
service, a Tl line, or another type of special service.
Another feature of the present invention is that
it allows for multiple POTs circuits in conjunction
with a circuit for other types of telecommunications
services on one line card. By integrating POTs
circuits with circuits for special telecommunications
services it is possible to provide the infrequently
requested telecommunications services in addition to
the commonly used POTs services without having to have
a separate line card. In particular, line cards having
one coin circuit or one ISDN circuit and five POTs
circuits allow for a close statistical match between
the number of coin and ISDN circuits required and the
number of circuits supported by the equipment. Close
matching between the demand and the available circuits
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prevents having to have partially utilized line cards
in the telecommunications equipment, which would
require more than the minimum amount of space and
power. Optimizing the line card results in a more
efficient and cost-ef~ective network.
In a Fiber-to-the-Curb (FTTC) telecommunications
architecture, the present invention provides for the
deployment of line cards at an Optical Network Unit
(ONU) where the line cards have multiple POTs circuits
and one ISDN, coin phone, or special service circuit.
The present invention also allows for delivery of
special services by generating a Tl circuit on a hybrid
Tl line card at an ONU, and transmitting the Tl signal
to a special services unit, where a special service
line card is used to generate the subscriber interface
for that special service. The hybrid Tl line card
contains ~our POTs circuits and one Tl circuit, thereby
allowing the card to be used for POTs services in
addition to the Tl service. Dedicating a line card to
Tl service without providing POTs services would
utilize an entire slot in the ONU and severely limit
the POTs capacity o~ the ONU.
These and other features and objects of the
invention will be more fully understood from the
following detailed description of the preferred
embodiments which should be read in light of the
accompanying drawings.
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Brie~ Description O~ The Drawings
The accompanying drawings, which are incorporated
in and form a part o~ the specification, illustrate the
embodiments of the present invention and, together with
the description serve to explain the principles of the
invention.
In the drawings:
FIG. 1 shows a Fiber-to-the-Curb network;
FIG. 2 shows a functional block diagram of a
Broadband Network Unit;
FIG. 3 shows a ~unctional block diagram of a dual
line Universal Voice Grade card circuit;
FIG. 4 shows a functional block diagram of a dual
line Univer~al Voice Grade/ISDN circuit;
15FIG. 5 shows a functional block diagram of a
Universal Voice Grade/coin circuit;
FIG. 6 shows a method of delivering special
services in a FTTC network using a T1 hybrid card;
FIG. 7 shows an architectural view of a T1 hybrid
card; and
FIG. 8 shows a ~lock diagram of a T1 circuit.
Detailed De~cription
Of The Preferred ~mho~ nt
25In describing a preferred embodiment of the
invention illustrated in the drawings, specific
terminology will be used for the sake of clarity.
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However, the invention i8 not intended to be limited to
the specific terms so selected, and it is to be
understood that each specific term includes all
technical equivalents which operate in a similar manner
to accomplish a similar purpose.
Table o~ Contents
I. Fiber-to-the-curb systems
A. System overview
B. Broadband Network Unit overview
II. Use o~ W G+ cards
III. Universal Voice Grade circuit
IV. Universal Voice Card + circuits
A. W G/ISDN circuit
B. W G/coin circuit
V. Delivery o~ special services
VI. Uses o~ the invention
I. Fiber-to-the-curb systems
A. SYstem overview
FIG. l illustrates a FTTC system which comprises a
Broadband Digital Terminal (BDT) lO0, which is
connected by an optical ~iber 200 to a Broadband
Networ~ Unit (BNU) llO. The BNU llO contains an
optical receiver and transmitter to receive signals
~rom and send signals to the BDT lOO, as well one or
more Universal Voice Grade cards 140 which connect to
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residences 175 via twisted pair drop cable 260. In the
residence 175 the in-home twisted pair cable 280
connects the telephone 185 to the twisted pair drop
cable 260. For the purposes of the present invention,
the term Broadband Digital Terminal can be used
interchangeably with the term Host Digital Terminal.
Similarly, the term Broadband Network Unit can be used
interchangeably with the term Optical Network Unit.
In a typical application BNU 110 serves 8
residences 175, each residence having one or more
twisted pair drop cable 260 coming from the BNU 110.
Each BDT 100 typically serves 64 BNUs 110.
The BDT 100 is connected to telecommunications
networks via a Public Switched Telecommunication
Network (PSTN) switch 10, and networks for advanced
services such as the Asynchronous Trans~er Mode IATM)
network 7. The interface to the PSTN switch 10 is the
switch interface 12, which in the US will be speci~ied
by Bellcore specification TR-TSY-000008, TR-NWT-000057
or TR-NWT-000303. The BDT 100 can also receive special
services signals from private or non-switched public
networks.
The FTTC system can be controlled through the use
of an Element Management System (EMS) 150 which is
software which runs on a workstation or computer which
is connected to the BDT 100. The EMS 150 provides the
ability to provision services or equipment which is
--10--
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e~fect the ability to modi~y the state of equipment in
the system or provide new services. The EMS 150 can
typically be operated locally by an operator at the
- workstation or PC, or remotely via a connection through
5 the PSTN switch 10 or the ATM network 7. The EMS 150
also provides the ability to monitor and control the
WG cards 140 in the BNU 110.
Telecommunications systems are based on standards
which have evolved over many years and insure
compatibility o~ equipment from dif~erent manufacturers
as well as providing clearly de~ined and precise
specifications for different types of
telecommunications services so that these services can
be provided across geographic boundaries in a network
with various generations o~ analog and digital
telecommunications equipment. For FTTC systems the
Bellcore specification TA-NWT-OOO909, entitled "Generic
Requirements and Objectives for Fiber in the Loop
Systems,~ Issue 2, December 1993, provides a
comprehensive description o~ the requirements ~or FTTC
systems as well as signaling and transmission
requirements for W G circuits, and is incorporated
herein by reference.
A WG circuit is de~ined as one which can provide
either a loop start or ground start line/trunk
interface with no intervention by a cra~tsperson at the
~ site o~ the W G circuit. In the present embodiments,
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the UVG card 140 supports 13 of the 14 locally switched
special services as described in Section 3.1 of the
Bellcore specification TA-NWT-000909, entitled "Generic
Requirements and Objectives for Fiber in the ~oop
Systems." The service not supported is Data Inward
Dial ~DID).
B. Broadband Network Unit overview
A block diagram of the BNU 110 shown in FIG. 1 is
illustrated in FIG. 2. The BNU 110 contains a
Broadband Network Unit Power Supply (BNPS) 804 which
receives a voltage ~rom an external source at power
supply header 848, and can power terminal equipment by
connections made at a 4-drop header 856. The BNU 110
further contains a BNU Common Control (BNCC) 800 which
receives signals from optical fiber 200 at an optical
connector 844. The BNCC 800 contains the circuitry to
send and receive optical si~nals, as well as a
microprocessor and associated software to communicate
20 with the BDT 100 and control the WG cards 140.
As illustrated in FIG. 2, the BNU 110 can contain
UVG cards 140 which further contain a dual line WG
circuit 812. The dual line UVG circuit is further
illustrated in FIG. 3. As shown in FIG. 2, the BNU 110
can also contain W G+ circuits 818 which may be a
WG/coin circuit 816 such as the one shown in FIG. 5, a
WG/ISDN circuit 814 such as the one shown in FIG. 6, a
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WG/special services circuit, or a W G/Tl circuit.
Multiple embodiments o~ the BNU 110 are possible,
a first embodiment being a BNU-8 which nominally serves
8 residences 175 and can contain up to two insertable
WG cards 140, two insertable W G+ cards 141 or a
combination thereof.
An alternate embodiment o~ BNU 110 is a BNU-16
which nominally serves 16 residences 175 and can
contain up to ~our insertable W G cards 140, ~our
insertable W G+ cards 141 or a combination thereof.
The WG cards 140 may have ~rom one to four dual
line W G circuits 812, and the WG+ card 141 may have
one W G/coin circuit 816 with the remainder o~ the
circuits being W G circuits 812, or it may have one
WG/ISDN circuit 814 with the remainder o~ the circuits
being W G circuits 812. Hex cards which have three
dual line WG circuits 812 are believed to be the most
cost e~ective, as are hex cards with two dual line WG
circuits 812 and one W G/coin circuit 816, or hex line
cards with two dual line WG circuits 812 and one
WG/ISDN circuit 814.
II. Use o~ W G+ cards
Tables I and II illustrate the services supported
by a BNU-8 and BNU-16 respectively with various
combinations o~ hex or quad WG and hex or quad WG+
cards. From these tables it can be seen that the use
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of WG+ cards allows the IDSN or coin penetration
supported to vary from 09~ to 25~. This can be
accomplished with an inventory of no more than 6 cards:
hex and quad W~ cards 14 0, hex and quad WG+ cards
141 containing one coin/l~VG circuit 816, and hex and
quad WG+ cards 141 containing one ISDN/WG circui'c
814 .
Alternately, by maintaining an inventory of 4
cards only (hex WG cards 140, hex WG~ cards 141
containing one coin/WG circuit 816, and hex WG+ cards
141 containing one ISDN/WG circuit 814) the same range
o~ penetration can be achieved, but with fewer
increment s .
The WG penetration supported exceeds 100~ when
some number of subscribers request a second telephone
line for a WG service. For this reason greater than
100~ penetration occurs in Tables I and II.
Table I
Services supported by BNU 8 with W G and W G+ cards
WG quad WG+ quad WG hex WG+ hex WG ISND/coin
car~scardscard3cardspenetration penetration
supported supported
2 lO0 00~ 0.00
1 1 125.00~ o.00
2 150 00~ o 00~
1 1 87 50~ 12 50%
1 1 137 50~ 12.50
1 1 112 50% 12 50
1 1 112.50% 12.50~
1 1 100 00~ 25.00%
2 75 00~ 25 00~
2 125.00~ 25 00%
-14-
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Table II
Servicect ~upported by BNU 16 with WG and WG+ cards
WG quad UVG+ quad WG hex WG+ hex UVG ISND/coin
cards card3 cards cards penetration penetration
supported supported
4 100.00% 0.00~
3 1 112.50~ 0,00%
2 2 125.00~ 0.00%
1 3 137.50% 0,00%
4 150.00% 0.00%
0 3 1 93.75% 6.25%
2 2 87 50% 12.50%
1 3 81.25% 18.75%
1 1 1 l112 50~ 12.50%
2 1 1106 . 25%18 75.
2 2137 50 12.50
2 1 1118.75 6 . 25~
1 1 2 118 75 6 . 25%
3 1106 . 25 6.25%
1 3118.75 18.75~
3 1 93.75 18.75%
1 3 131.25 6.25~
2 2 112 50 12.50%
4 75.00 25 00%
4125.00 25 00%
1 3 131 25 18.75~
1 3112 50 25 00%
3 1 143.75 6 . 25%
3 187.50 25.00%
III. Universal Voice Grade circuit
The W G card 140 illustrated in FIGS. 2 and 3
provides POTs service to a number of residences 175
served by a BNU 110, and can provide this service
through a Loop Start or Ground Start line/trunk
interface. Typically, 6 ~ubscriber voice circuits
(POTs lines) are served from a W G card 140. Referring
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to FIG . 2 the WG card 140 contains three dual line WG
circuits 812 such as the one illustrated in FIG. 3.
WG card connectors 860 allow connection of the
WG card to backplane interconnects 808 which provide
connectivity to the BNCC 800. The backplane
interconnectg 808 provides connections to a number of
signals including data buses which contain
telecommunications data for subscribers as well as
control information from the BDT 100 or the BNCC 800,
and power and ground for the WG card itself.
Referring again to FIG. 3, the WG card contains a
common control bus signal 882 which connects a
Telephony Inter~ace Unit Application Specific
Integrated Circuit (TIUA) 880 to BNCC 800.
TIUA 880 provides the time division multiplexing
functions, state machine functions, and general control
functions for the generation o~ a voice signals in
conjunction with the other components of WG circuit
812.
An Electrically Erasable Programmable Read Only
Memory (EEPROM) 886 is used in conjunction with TIUA 880
for the storage of operational data required when WG
card 140 is initially powered.
In addition to TIUA 880, each WG card 140 also
includes a microcontroller and SRAM. These are
indicated respectively by re~erence characters 884 and
887. Microcontroller 884 may be implemented using
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generally available products such as ~or example a
Motorola 68HCllD3, and a suitable design choice for
SRAM 887 is a 32K x 8 SRAM. A suitable SRAM for this
purpose lS an Integrated Devices Technology SRAM
denoted IDT 712565A. Of course other manufacturer's
devices having the indicated source capacity may also
be used as a substitute.
A ringing generator 890 is included on the WG
card 140, which is capable of providing 40 V RMS into a
5 ringing equivalent (REN) load. Ringing generator 890
is controlled by a digital pulse train 892 ~rom TIUA
880, and receives a -130 V signal 894. The output o~
the ringing generator is ringing voltage 896.
A Pulse Code Modulated (PCM) bus 883 and serial
bus 885 transfer signals to and ~rom TIUA 880 to
subscriber line audio circuits. A single component
known as a dual audio line subscriber audio circuit is
used to provide a first audio line subscriber audio
circuit 900 and a second subscriber line audio circuit
902 in dual line WG circuit 812 The Advanced Micro
Devices' product denoted AM79C031, known by its
trademarked name as DSLAC~ is a suitable design choice.
When used herein, the term DSLAC~ re~ers generically to
a dual subscriber line audio circuit. An alternate
design choice for a dual audio line subscriber audio
circuit is the Siemens SiCoFi device.
The DSLAC~s are connected to a Subscriber Line
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Interface Circuit (SLIC) 906. There are two SLICs 906
in each dual line W G circuit 812. In addition to
generating the voice circuit interface for basic
telephone service, each SLIC also performs loop sense
and ring trip detection, tip and ring polarity
reversals, provides ring delay drivers and provides a
battery switch function to allow two different battery
voltages to be used. Subscriber line interface circuits
906 may be implemented utilizing commercially available
devices such as the Advanced Micro Devices product
denoted AM7949.
A solid state relay 91O is used in each subscriber
circuit to allow the application of the ringing voltage
896 through a lOO Q ringing resistor 898, as well as
for providing metallic test access from the test in bus
912 and test out bus 914 toward the communications
channel formed by the WG circuit and toward the
twisted pair drop cable 260. AT&T part number ATTL7583
is a suitable design choice for solid state relay 910.
A transient over-voltage protector 918 is used to
protect the solid state relay 91O from excessive
voltages. A suitable design choice for the transient
over-voltage protector 918 is the Teccor P2103 200 V
Sidactor.
Protection resistor 920 consists of two resistors,
one in series with the tip (T) line 266 and on in
series with the ring (R) line 268 which together form
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the twisted pair drop cable 260. The protection
resistors serve to protect the WG circuit from
overvoltages, in particular overvoltages due to
lightning strikes. Thick ~ilm or wirewound ~usible
protection resistors are typically used. A suitable
design choice ~or a protection resistor in protection
resistor 920 is a 50 Q thick film resistor on a ceramic
substrate.
A gas tube or carbon block device at the premises
is used in conjunction with the transient over-voltage
protector 918 and protection resistor to provide over-
voltage protection. Protection resistor 920 presents
suf~icient resistance such that in the event o~ a
lightning strike the voltage at the premises will
-15 remain su~iciently high to activate the gas tube or
carbon block in addition to activating transient over-
voltage protector 918.
IV. Universal Voice Card + circuits
A. WG/ISDN circuit
The WG/ISDN circuit 814 is illustrated in FIG. 4.
The circuit can provide ISDN Basic Access using 3-DS0
or 4:1 multiplexing. The inter~ace to the subscriber
is a U-inter~ace operating over two wires at a data
rate of 160 kb/s ~ull duplex.
The PCM bus 883 interconnects the TIU ASIC 880
with the U transceiver 862. The U transceiver 862
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provides basic ISDN Basic Access functionality as
described in the American National Standards Institute
T1.601-1991 specification. ~ suitable design choice
for the U transceiver 862 is the Siemens ISDN
Echocancellation Circuit IEC-Q 2091.
The U transceiver 862 is connected to the 4-2 wire
hybrid 864 which converts half duplex transmission to
full duplex transmission at the U interface. The 4-2
wire hybrid 864 can be realized using resistors and
capacitors or with a single IC such as the Pulse
Engineering PE36005W single chip hybrid.
The 4-2 wire hybrid is connected to the
transformer 865. A suitable design choice for the 4-2
wire hybrid is the Pulse Engineering PE-65575 line
transformer.
The transformer 865 is connected to a solid state
relay 910 which provides access for the test in bus 912
and test out bus 914. Switching in and out of ringing
is not required in the ISDN application.
A transient over-voltage protector 918 is used to
protect the solid state relay 910 from excessive
voltages. A suitable design choice for the transient
over-voltage protector 918 is the Teccor P2103 200 V
Sidactor.
Following the transient over-voltage protector 918
a Positive Temperature Coefficient (PTC) device 866 is
used to protect the circuit from excessive currents.
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B. WG/coin circuit
The WG/coin circuit 814 is illustrated in FIG. 5.
Operation of the WG/coin circuit 814 is similar to
- that of the W G circuit 812 with the addition of coin
check/control 872 which permits the application of the
four coin voltages: +48V, 874; -48V, 876; +80V, 878;
and -80V, 879. These voltages are used to control the
functions of coin collect, coin refund, coin presence
check, and coin base amount check, and keypad disable.
10 The voltages 874, 876, 878 and 879 are applied via the
solid state relay 910.
The requirements for coin signaling are described
in detail in Section 4.6 of Bellcore specification TA-
NWT-O009O9, entitled "Generic Requirements and
Objectives for Fiber in the Loop Systems," Issue 2,
December 1993. Circuits for meeting these signaling
requirements are known by those skilled in the art.
V. Delivery of s~ecial services
Because there is a re~uirement to provide special
services in addition to POTs, coin, and ISDN lines,
there is a need for a method and apparatus of
delivering those services efficiently from the BNU 110.
FIG. 6 illustrates a method in which special
services are delivered from BNU 110 by the use of a T1
hybrid card A610, which includes POTs circuits and one
- T1 circuit. The T1 circuit is used to provide a T1
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W097/29585 PCT~S97/01245
signal containing 24 DS0's to a Special Service Unit-8
(SSU-8) A620, which has plug-in cards for special
services. The special services are then provided using
a telecommunications link A618 and appropriate Customer
Premises Equipment (CPE) A630. By providing special
services in this way it is not necessary to have
special service cards resident in BNU 110.
Referring to FIG. 6, delivery of special services
is accomplished by providing DS0 channels to BDT 100
either by means of a D4 signal A604 which contains up
to 24 special services circuits, or by using a Central
Office Terminal Channel Bank A600 which receives
unbundled specials signals A602 and ~orms a DSl signal
A601. Signals are transported to BNU 110 via optical
1~ fiber 200. Tl hybrid card A610 provides a Tl signal
over a four-wire twisted pair loop A623 to a Special
Service Unit-8 (SSU-8) A620. SSU-8 A620 accepts
whatever type of special services card is needed to
provide the special service. Telecommunications link
A618 can be twisted pair, coaxial cable, or any other
type of telecommunications link required ~or the
special service.
The special service unit shown in FIG. 6 as SSU-8
A620 can be located inside of a building, or can be
located outside on a telephone pole or in any other
suitable location for network equipment. A number of
existing channel banks can be used as special service
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unit, and the size o~ the special service unit can vary
~rom a two-card unit up to a 24 card unit. The
construction of channel banks is well understood by
- those skilled in the art.
In addition to providing special services, T1
hybrid card A610 contains four POTs circuits, and can
provide POTs services to residences 175 using via
twisted pair drop cable 260. In the residence 175 the
in-home twisted pair cable connects the telephone 185
to the twisted pair drop cable 260.
FIG. 7 illustrates the T1 hybrid card A610 in
~urther detail, showing ~our POTs circuits, POTS1
A72Oa, POTS2 A72Ob, POTs3 A720c, and POTS4 A72Od. A
DS1 circuit A730 is present to transmit and receive the
15 T1 signal to and ~rom SSU-8 A620. The DS1 common
daughter board A710 plugs into the mother board A709
and provides the inter~ace ~unction to the BNCC 800.
The DS1 common daughter board A710 contains a T1 ASIC
A818, T1 microprocessor A822, external T1 Static Random
20 Access Memory (T1 S~AM) A826, and T1 ~P SRAM A824. A
separate processor (microcontroller) is used ~or the T1
circuit ~unctions in order not to burden the
microcontroller 824 which is used ~or POTs circuit
functions.
The common POTs block A740 provides the functions
common to all o~ the POTs circuits. Included in the
common POTs block A740 are the microcontroller 884,
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SRAM 887 TIUA 880, EEPROM 886, and ringing generator
890 illustrated in FIG. 3.
The DS1 clrcuit A730 is comprised of the clock
adapter A820, framer A816, and Line Interface Unit
~LIU) A814.
A block diagram of the entire T1 circuit is
illustrated in further detail in FIG. 8. The receive
pair A810 and transmit pair A812 which form the four-
wire twisted pair loop A623 are connected to the ~ine
Interface Unit (LIU) A814. A suitable design choice
for the ~IU A814 is the Level One LXT350 short haul
TltE1 Transceiver.
A ~ramer A816 per~orms the ~raming ~unctions on
the received and transmitted signals. A suitable
design choice for ~ramer A816 is the BT8360.
A clock adapter A820 is used to generate a 1. 544
MHz clock A823 ~rom the 4.096 MHz clock A821 which is
present on the hybrid T1 card A610. A suitable design
choice ~or the clock adapter is the Level One LXP604
Clock Adapter.
The Tl ASIC A818 is used to form the Tl signal
~rom the BNU payload. Tl ASIC A818 is connected to TIU
BUS 882 which is connected to BNCC 800 via backplane
interconnects 808. The Tl ASIC A818 is responsible for
interfacing to backplane interconnects 808 and
provides the processor interface and address decoding.
TI ASIC A818 stores a 4 ~rame downstream signaling
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history and translates upstream and downstream
signaling on a per DS0 basis.
External T1 Static Random Access Memory (T1 SRAM)
A826 is utilized in conjunction with T1 ASIC A818 for
storing 4 signaling ~rames required for signaling
freeze conditions. The T1 SRAM A826 is also used for
storing downloaded signaling translation tables. The
processor loads the tables via a memory banking method,
through T1 ASIC A818. A suitable design choice for the
size of T1 SRAM A826 is 32K*8, although only a few
hundred bytes of memory may be required in actual
operation.
A microprocessor A822 is used to configure the
various components on the T1 hybrid card A610. A
suitable design choice is a Motorola 68HCllD3
microprocessor running at 2MHz. The microprocessor
A822 will download code from the BNCC 800 via the data-
link. External ~P Static Random Access Memory (~P
SRAM) A824 is utilized for storage of program
information. A suitable design choice for the size of
the ~P SRAM A824 is a 128K*8 SRAM, although only 64K is
addressable space. The microprocessor A822 performs
any necessary alarm monitoring and performance
monitoring functions required, along with
initialization of the LIU A814, framer A816, and T1
SRAM A826.
In a preferred embodiment, four POTs circuits are
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placed on a T1 Hybrid Card with one T1 circuit. This
is because 2 twisted wire pairs are used ~or T1
service, and there are 6 pairs available ~or each WG
card 140, W G+ card 141, or Tl hybrid card A610. In an
alternate embodiment, 5 POTs circuits can be placed on
a card with one Tl circuit. This alternate embodiment
requires connections ~or an additional twisted pair
In an alternate embodiment the special service
circuits can be placed on a WG+ card 141, in a manner
similar to the placement of ISDN or coin circuits. The
construction o~ the special service circuits are well
~nown to those skilled in the art. In this alternate
embodiment, a special services unit is not required,
since the special services circuit is deployed directly
in BNU 110.
YI. U~es of the invention
As an example of the use o~ the invention, it is
possible to provision a BNU 110 which serves 8
residences 175 with two hex W G cards and achieve 150
penetration ~or W G services by supporting 12 W G
circuits, and later replace one of the W G cards with
hex W G+ card, thus supporting ll W G circuits and one
coin or ISDN circuit. Similarly, both hex WG cards
can be replaced with two WG+ cards to support 10 WG
lines and 2 coin/ISDN lines or 1 coin and l ISDN line.
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As an example of the use of the invention for the
delivery of special services, a BNU 110 could be
located in a residential area which contains a small
business which requires a lottery circuit, which is a
special service circuit. The BNU 110 could be
provisioned with one hex WG card and one T1 hybrid
card, and a special services unit could be deployed in
the business or outside the business. A lottery
circuit card would be placed in the special services
unit, and the business would have the appropriate CPE
for lottery services. In this way a special lottery
circuit card does not need to be deployed in the BNU.
Although this invention has been illustrated by
reference to specific embodiments, it will be apparent
~5 to those skilled in the art that various changes and
modifications may be made which clearly fall within the
scope of the invention. The goal of the invention as an
apparatus for providing a mixture of WG, coin, ISDN,
or special services remains the same however. The
invention is intended to be protected broadly within
the spirit and scope of the appended claims.
Therefore, the spirit and scope of the appended claims
should not be limited to the description of the
preferred versions contained herein.
