Unified access platform for simultaneously delivering voice and cell-based services

A Unified Access Platform capable of providing telephone and high speed data services in a number of different local loop configurations. In a first embodiment, a broadband digital terminal (BDT receives high speed data and telephony signals, and combines them into a cell based signal which is transported to an access multiplexor. At the access multiplexor, a first linecard generates an analog telephone signal, and a second linecard generates a high-speed data signal. Analog telephone service is provided over a first twisted wire pair drop cable, while the high speed data service is provided over a second twisted wire pair drop cable. In an alternate embodiment, the BDT's cell based signal is transported to two separate terminals. Analog telephone service is provided to a subscriber location from the first terminal, while high speed data service is provided to a second subscriber location from the second terminal. Yet another embodiment provides analog telephone and high speed data services from a single linecard located in an access multiplexor. The analog telephone and high speed data signals are generated on the linecard and combined using a diplexor. At the residence, a receiving diplexor is used to separate the combine signal. Still another embodiment generates a high speed data signal at an access multiplexor which contains a digital representation of the analog telephone signal. The high speed data signal is sent to the residence, where a receiving device generates an analog telephony signal and transmits the high speed data signal to appropriate terminal equipment.

FIELD OF THE INVENTION
 The present invention relates to a Unified Access Platform (UAP) which is
 capable of providing telephone and high speed data services in a number of
 different local loop configurations.
 BACKGROUND OF THE INVENTION
 New telecommunications services such as Internet access are being offered
 by phone companies. There is a growing demand for high speed Internet
 access, in addition to other new services such as digital television,
 which require special high speed connections from networks to residences.
 However, basic telecommunications services such as Plain Old Telephony
 service (POTs) are at present the main source of revenue for telephone
 companies. These services are typically provided from a telephone central
 office to the residences over twisted copper wire pairs which in some
 cases have been in place for many years, and in some cases have been
 recently upgraded.
 The part of the telecommunications network that connects a telephone
 central office to the subscriber residences is known as the access network
 or the local loop. The local loop technology is still based primarily on
 the use of twisted wire pairs, but some optical fiber has been used to
 reach terminals for telephone service. To date there has been little
 deployment of high speed digital data services. When used herein, the term
 high speed data services refers to any type of digital data service
 including Internet access and digital video.
 Access network equipment for telecommunications services must be able to
 support POTs services as well as being able to support new digital
 services which will eventually have high penetration rates.
 A number of technologies for providing high speed digital data services
 have been explored and include wireless, Hybrid Fiber Coax (HFC),
 Fiber-to-the-Curb (FTTC), Fiber-to-the-Home (FTTH), Asymmetrical Digital
 Subscriber Line (ADSL) and Very high rate Digital Subscriber Line (VDSL).
 A general conclusion is that although all of these technologies will play a
 role in phone companies' long term business objectives, the majority of
 today's upgradable narrowband deployment needs will best be met by
 switched wireline infrastrutures based on FTTC, ADSL, and VDSL
 technologies.
 Because the service areas are all different in terms of the length and
 quality of the telephone wire between the telephone central office and the
 residences, the number and type of homes and their distance from the
 telephone central offices, no single technology or configuration of that
 technology will be optimized for all applications and all deployment
 scenarios. It can also be the case that a central office may be located in
 an area which has both urban and suburban characteristics (e.g. some old
 apartment buildings as well as new housing developments), so that a
 mixture of FTTC, ADSL, and VDSL technologies are required.
 Present solutions to the problem of delivering signals over twisted wire
 pairs involve placing additional equipment in the telephone central office
 to transmit and receive high speed data signals, and to convert the high
 speed data signals from a packet based signal to a circuit based signal
 compatible with the Public Switched Telecommunications Network (PSTN).
 Sometimes, because of the distance between the subscriber residence and the
 central office, the equipment for transmission and reception of high speed
 data signals over twisted wire pair must be placed remote from the central
 office, and closer to the subscriber residence. This can be accomplished
 by putting a device called a channel bank near an existing Remote Terminal
 (RT) which provides analog telephone service.
 For transmission over the twisted wire pair, the analog telephone signal
 must be combined with the high speed data signal using a diplexor. At the
 residence, a diplexor is used to separate the signals again.
 In the presently used configuration, numerous problems are encountered
 including the need to convert packet or cell based high speed data signals
 to frame based signals compatible with the public switched telephone
 network; the need to deploy additional racks of equipment in both the
 remote location and the central office to support the high speed data
 applications; the need to have separate computers to program the telephony
 equipment and high speed data equipment, and the need for external
 diplexors at the central office or remote terminal and the subscriber
 residence to combine the analog telephone signals with the high speed data
 signals and separate them back out again. In addition, there may be noise
 from the analog telephone signal which interferes with the high speed
 digital data signal.
 There is the need for a system which can combine high speed data signals
 with digital telephony signals and generate a combined high speed data and
 analog telephone signal which can be transmitted over twisted wire pair
 from a terminal which can be located in the central office or remotely.
 For these reasons it is necessary to have a flexible terminal which can be
 used in both the central office or in the field, and which can generate
 the analog telephone signal and high speed data signal on a single plug-in
 card. In addition, a means of transporting traditional voice signals
 combined with high speed data signals in the access network is required.
 SUMMARY OF THE INVENTION
 In a first embodiment high speed data and telephony signals are received at
 a broadband digital terminal, and combined into a cell based signal which
 is transported to an access multiplexor. At the access multiplexor an
 analog phone signal is generated on a first linecard, and a high-speed
 data signal is generated on a second linecard. Analog telephone service is
 provided over a first twisted wire pair drop cable, while the high speed
 data service is provided over a second twisted wire pair drop cable.
 In an alternate embodiment high speed data and telephony signals are
 received at a broadband digital terminal, and combined into a cell based
 signal which is transported to two separate terminals. Analog telephone
 service is provided to a subscriber location over a twisted wire pair from
 the first terminal, while high speed data services are provided to a
 second subscriber location from the second terminal.
 Another feature of the present invention is the ability to provide analog
 telephone and high speed data services from a single linecard located in
 an access multiplexor. The analog telephone and high speed data signals
 are generated on the linecard and combined using a diplexor. At the
 residence, a receiving diplexor is used to separate the analog telephone
 and high speed data signals.
 An alternate embodiment for simultaneous delivery of telephone service and
 high speed data is to generate a high speed data signal at an access
 multiplexor which contains a digital representation of the analog
 telephone signal. The high speed data signal is sent from the access
 multiplexor to the residence, where a receiving device generates an analog
 telephony signal and transmits the high speed data signal to the
 appropriate terminal equipment.
 The combined transport of digital telephony signals and high speed data
 signals in a cell based Asynchronous Transport Mode (ATM) format allows
 for flexible deployment of the access equipment and the ability to
 simultaneously support traditional telephone services as well as advanced
 digital data services.
 The access equipment can be configured such that analog telephone service
 can be provided to subscribers in one geographical location while
 simultaneously providing data service to subscribers in a different
 geographic location, all from one service platform which has telephone and
 data interfaces. The ability to provide a mix of services over different
 types and lengths of twisted wire pair drop cables allows for flexible
 provisioning of services. Combining voice, video, and data services for
 transmission over a variety of drop cable media while maintaining the
 ability to transport traditional analog telephony signals has not been
 previously accomplished.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
 In describing a preferred embodiment of the invention illustrated in the
 drawings, specific terminology will be used for the sake of clarity.
 However, the invention is 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.
 With reference to the drawings, in general, and FIGS. 1 through 15 in
 particular, the apparatus of the present invention is disclosed.
 FIG. 1 illustrates a Fiber-to-the-Curb (FTTC) network in which various
 devices in the residence 190 are connected to the Public Switched
 Telecommunications Network (PSTN) 100 or Asynchronous Transfer Mode (ATM)
 network 110. The devices in the residence 190 can include telephone 194,
 television (TV) 199 with a television set-top 198, computer with Network
 Interface Card (NIC) 191, and Premises Interface Device (PID)196 connected
 to a telephone 194.
 The FTTC network illustrated in FIG. 1 works by connecting a Broadband
 Digital Terminal 130 to the PSTN 100 and ATM network 110. The PSTN-BDT
 interface 103 is specified by standards bodies, and in the US are
 specified by Bellcore specifications TR-TSY-000008, TR-NWT-000057 or
 GR-NWT-000303. The BDT 130 can also receive special services signals from
 private or non-switched public networks. The physical interface to the
 PSTN is twisted wire pairs carrying DS-1 signals, or optical fibers
 carrying OC-3 optical signals.
 The interface to the ATM network-BDT interface 113 can be realized using an
 OC-3 or OC-12c optical interfaces carrying ATM cells. In a preferred
 embodiment, BDT 130 has two OC-12c broadcast ports, which receive signals
 carrying ATM cells, and one OC-12c interactive port which receives and
 transmits signals.
 An element management system (EMS)151 is connected to BDT 130 and forms
 part of the Element Management Layer (EML) which is used to provision
 services and equipment on the FTTC network, in the central office where
 the BDT 130 is located, in the field, or in the residences. The EMS 151 is
 software based and can be run on a personal computer in which case it will
 support one BDT 130 and the associated access network equipment connected
 to it, or can be run on a workstation to support multiple BDTs and access
 networks.
 Broadband Network Units (BNUs) 140 are located in the serving area and are
 connected to BDT 130 via optical fiber 160. Digital signals in a format
 which is similar to the Synchronous Digital Hierarchy (SDH) format are
 transmitted to and from each BNU 140 over optical fiber 160 at a rate of
 155 Mb/s. In a preferred embodiment optical fiber 160 is a single-mode
 fiber and a dual wavelength transmission scheme is used to communicate
 between BNU 140 and BDT 130. In an alternate embodiment a single
 wavelength scheme is used in which low reflectivity components are used to
 permit transmission and reception on one fiber.
 A Telephony Interface Unit (TIU) 145 in BNU 140 generates an analog Plain
 Old Telephony (POTs) signal which is transported to the residence 190 via
 a twisted wire pair drop cable 180. At the residence 190 a Network
 Interface Device (NID) 183 provides for high-voltage protection and serves
 as the interface and demarcation point between the twisted wire pair drop
 cable 180 and the inside twisted wire pairs 181. In a preferred embodiment
 TIU 145 generates POTs signals for six residences 190, each having a
 separate twisted wire pair drop cable 180 connected to BNU 140.
 As shown in FIG. 1, a Broadband Interface Unit (BIU) 150 is located in BNU
 140 and generates broadband signals which contain video, data and voice
 information. BIU 150 modulates data onto an RF carrier and transmits the
 data over a coaxial drop cable 170 to a splitter 177, and over inside
 coaxial wiring 171 to the devices in the residence 190.
 In a preferred embodiment 64 BNUs 140 are served by an BDT 130. Each BNU
 serves 8 residences 190. In an alternate embodiment, each BNU 140 serves
 16 residences 190.
 As shown in FIG. 1, each device connected to the inside coaxial wiring 171
 will require an interface sub-system which provides for the conversion of
 the signal from the format on the inside coaxial wiring 171 to the service
 interface required by the terminal equipment, which can be a telephone
 194, television 199, computer, or other device. In a preferred embodiment,
 the PID 196 extracts time division multiplexed information carried on the
 inside coaxial wiring 171 and generates a telephone signal compatible with
 telephone 194. Similarly, the television set-top 198 converts digital
 video signals to analog signals compatible with TV 199. The NIC card
 generates a computer compatible signal.
 In the system illustrated in FIG. 1, a Network Interface Device (NID) 183
 is located on the side of residence 190 at what is known in the industry
 as the network demarcation point. For the delivery of telephony services
 NID 183 is a passive device whose principal functions are lightning
 protection and the ability to troubleshoot the network by allowing
 connection of a telephone 194 to the twisted wire pair drop cable 180 to
 determine if wiring problems exist on the inside twisted wire pairs 181.
 FIG. 2 illustrates the use of a gateway 200 to generate signals compatible
 with the devices in the home, which are connected to the gateway 200 via
 inside twisted wire pairs 181 or inside coaxial cable wiring 210 and a
 splitter 177. The connection to the splitter is made using a
 gateway-splitter connection 210, which in a preferred embodiment is
 coaxial cable. A direct connection to a television can be made using a
 gateway-television connection 205, which in a preferred embodiment is a
 four conductor cable carrying an S-video signal.
 The use of a gateway 200 can reduce the number of devices required in the
 residence 190 to interface between the access network and the terminal
 equipment including television 199, telephone 194, and computer 193.
 FIG. 3 illustrates a FTTC network which relies on twisted wire pair drop
 cables 180 instead of coaxial drop cables 170. This embodiment is
 preferable when it is cost prohibitive to install coaxial drop cables from
 BNUs 140 to residences 190.
 As shown in FIG. 3, a Universal Service Access Multiplexor (USAM) 340 is
 located in the serving area, and is connected to BDT 130 via optical fiber
 160. An xDSL modem 350 provides for the transmission of high-speed digital
 data over the twisted wire pair drop cable 180 to and from residence 190.
 When used herein, the term xDSL refers to any one of the twisted wire pair
 digital subscriber loop transmission techniques including High Speed
 Digital Subscriber Loop, Asymmetric Digital Subscriber Loop, Very high
 speed Digital Subscriber Loop, Rate Adaptive Digital Subscriber Loop, or
 other similar twisted wire pair transmission techniques. Such transmission
 techniques are know to those skilled in the art. The xDSL modem 350
 contains the circuitry and software to generate a signal which can be
 transmitted over the twisted wire pair drop cable 180, and which can
 receive high speed digital signals transmitted from gateway 200 or other
 devices connected to the subscriber network.
 Traditional analog telephone signals are combined with the digital signals
 for transmission to the residence 190 and a NID/filter 360 is used to
 separate the analog telephone signal from the digital signals. The
 majority of xDSL transmission techniques leave the analog voice portion of
 the spectrum (from approximately 400 Hz to 4,000 Hz) undisturbed. The
 analog telephone signal, once separated from any digital data signals in
 the spectrum, is sent to telephone 194 over the inside twisted wire pairs
 181.
 The digital signals which are separated at the NID/filter 360 are sent from
 a separate port on the NID/filter 360 to the gateway 200. The gateway
 serves as the interface to the devices in the residence 190 including the
 television 199, the computer 193, and additional telephone 194.
 The central office configuration illustrated in FIG. 3 includes a Universal
 Service Access Multiplexor Central Office Terminal (USAM COT) 324
 connected to BDT 130 via a USAM COT-BDT connection 325, which in a
 preferred embodiment is an STS3c signal transmitted over a twisted wire
 pair. The PSTN-USAM COT interface 303 is one of the Bellcore specified
 interfaces including TR-TSY-000008, TR-NWT-000057 or TR-NWT-000303. The
 USAM COT 324 has the same mechanical configuration as the USAM 340 in
 terms of power supplies and common control cards, but has line cards which
 support twisted wire pair interfaces to the PSTN (including DS-1
 interfaces) and cards which support STS3c transmission over twisted wire
 pair for the USAM COT-BDT connection 325.
 A Channel Bank (CB) 322 is also used in the central office to connect
 specials networks 310, comprised of signals from special private or public
 networks, to the access system via the specials networks-CB interface 313.
 In a preferred embodiment, the CB-USAM COT connection 320 are DS1 signals
 over twisted wire pairs.
 When used herein the term subscriber network refers in general to the
 connection between the BNU 140 and the devices or gateway 200 in the
 residence 190 or the connection between USAM 340 and the devices or the
 gateway in the residence 190. The subscriber network may be comprised of
 coaxial cable and a splitter, twisted wire pairs, or any combination
 thereof.
 Although FIG. 2 and FIG. 3 illustrate the gateway 200 located inside the
 living area of residence 190, the gateway can be located in the basement,
 in the garage, in a wiring closet, on an outside wall of the residence
 190, in the attic, or in any of the living spaces. For outside locations
 gateway 200 will require a hardened enclosure and components which work
 over a larger temperature range than those used for a gateway located
 inside the residence 190. Techniques for developing hardened enclosures
 and selecting temperature tolerant components are known to those skilled
 in the art.
 FIG. 4 illustrates system architectures which have been used to provide
 high speed data services over existing twisted wire pair networks. In
 these systems a Host Digital Terminal (HDT) 422 is connected to the PSTN
 100 via twisted wire pairs 423 or optical fiber 160. A Remote Terminal
 (RT) 430 is connected to the HDT 422 via one or more optical fibers 160.
 An analog POTs linecard 432 is located in RT 432 and can provide analog
 telephone services over distances up to approximately 12,000 ft.
 As shown in FIG. 4, an analog POTs linecard 432 can be located directly in
 HDT 422 to provide analog telephone service to residences which are within
 12,000 ft. of the telephone central office or remote structure.
 The architecture illustrated in FIG. 4 is based on the provisioning of
 telephone service to subscribers. The Operational and Support Systems
 (OSS) 410 connected to HDT 422 support basic and advanced telephone
 services, but does not support advanced high speed data services.
 For the additional high speed data services, the traditional approach has
 been to utilize overlay equipment to provide those services. FIG. 4.
 illustrates the use of ADSL Channel Banks (ADSL CBs) 414 which are added
 to the network to provide high speed data services. An ADSL CB 414 with an
 xDSL modem 350 can be added at the central office, and routes data signals
 into an Inter-Networking Unit (INU) 400 which takes data signals which are
 typically in the form of Internet Protocol (IP) packets and adapts them
 for transmission on the PSTN 100 in a PSTN compatible format such as frame
 relay, or switched multimegabit data service, or switched 56 data service.
 Because the OSS 410 does not support high speed data services, a separate
 computer 193 is used to configure the INU 400 and provision data services.
 Referring to the upper portion of FIG. 4, a fiber optic transceiver 351 can
 be used in ADSL CB 414 to transmit high speed data signals over an optical
 fiber 160 to an ADSL CB 414 located in the local loop, remote from the
 central office. The ADSL CB 414 in the local loop can be located near the
 RT 430, and a line side diplex filter 418 is used to combine the analog
 telephony signal with the high speed data signal. The combined signals are
 transmitted over twisted wire pair drop cable 180 to a subscriber side
 diplex filter 420 which separates the high speed data signal from the
 analog telephony signal.
 The lower portion of FIG. 4 illustrates how high speed data can be
 transmitted from an ADSL CB in the telephone central office or remote
 office to a subscriber. The high speed data signals generated on XDSL
 modem 350 are transmitted over twisted wire pair 423 to a line side diplex
 filter 418 which combines the high speed data signal with the analog
 telephony signal generated on the analog POTs linecard 432. The combined
 signals are transmitted over twisted wire pair drop cable 180, and are
 received at the residence 190, where a subscriber side diplex filter 420
 separate the high speed data signal from the analog telephony signal. The
 high speed data signals are transmitted over the inside twisted wire pairs
 181 to devices in the residence, while the analog telephony signal is
 transmitted to telephone 194.
 FIG. 5 illustrates one embodiment of the present invention for providing
 both high speed data and voice services from a single access network
 platform. In this architecture, a BDT 130 is connected to an ATM network
 110 via optical fibers 160 using the ATM network-BDT interfaces 113, and
 simultaneously to the PSTN 100 via optical fibers 160 and twisted wire
 pairs 423 using the PSTN-BDT interfaces 103 previously described ATM/TDM
 description. An EMS 151 which consists of a computer 193 and specialized
 EML software allows for the provisioning of traditional telephone as well
 as new services. OSS 410 supports the provisioning of traditional
 telephone services, and as the OSS 410 is updated, EMS 151 allows for new
 services to be provisioned from the OSS 410 using flow-through
 provisioning.
 At the central office side of the network in FIG. 5, a USAM COT in the
 Central Office (USAM COT-CO) 530 can be used to interface telephony
 signals from TR-TSY-000008, TR-NWT-000057 or GR-NWT-000303 interfaces
 provided by a public or private network to the BDT 130. This is
 accomplished by receiving the signals in the TR-008, TR-057, and GR-303
 formats transmitted over twisted wire pairs 423 at USAM COT-CO 530,
 grooming and mulitplexing those signals as required, and transmitting them
 to BDT 130 over twisted wire pairs 423 using a STS3c format. In this way
 the BDT can be used to handle signals from additional networks.
 Additionally, signals from other telecommunications services networks,
 typically referred to as "specials," can be routed to the BDT 130 through
 the use of a Channel Bank 322 which receives "specials" on twisted wire
 pairs 423, multiplexes and grooms the signals, and transmits them on to
 USAM COT-CO over twisted wire pairs 423. The USAM COT-CO can perform
 additional grooming and multiplexing as required, and transmit the signals
 to BDT 130.
 Referring to the upper portion of FIG. 5, an optical signal in an SDH type
 format at 155 Mb/s can be transmitted via optical fiber 160 to USAM ADSL
 in a Remote Terminal configuration (USAM ADSL-RT) 520. A telephony/xDSL
 linecard 353 contained within the USAM ADSL-RT 520 is used to generate
 both an xDSL signal as well as an analog telephony signal. In the case of
 the system shown in FIG. 5, the telephony/xDSL linecard 353 generates an
 ADSL signal in addition to the analog telephony signal. The architecture
 for the telephony/xDSL linecard 353 is described later in this
 specification and is illustrated in FIGS. 11A-12B.
 In the case of the USAM ADSL-RT 520 the combined telephony and high speed
 data signals are transmitted over the twisted wire pair drop cable 180 to
 a subscriber side diplex filter 420, which separates the separate the high
 speed data signal from the analog telephony signal. The high speed data
 signals are transmitted over the inside twisted wire pairs 181 to devices
 in the residence, while the analog telephony signal is transmitted to
 telephone 194.
 The lower portion of FIG. 5 illustrates the use of a USAM ADSL in a Central
 Office configuration (USAM ADSL-CO) 510. In this instance, high speed data
 and digitized telephony signals are transmitted from BDT 130 to USAM
 ADSL-CO 510 over twisted wire pairs 423. The USAM-ADSL-CO contains a
 telephony/xDSL linecard 353 which generates both an xDSL signal as well as
 an analog telephony signal. These signals are transmitted to residence
 190, where there is a subscriber side diplex filter 420 which separates
 the high speed data signal from the analog telephony signal. The high
 speed data signals are transmitted over the inside twisted wire pairs 181
 to devices in the residence, while the analog telephony signal is
 transmitted to telephone 194.
 FIG. 6 illustrates an alternate embodiment, in which a USAM VDSL 620 is
 used to provide both the telephony and data signals. In this configuration
 a telephony/xDSL linecard 353 is used to generate both telephony and high
 speed data signals, but the high speed data signals are in a Very high
 speed Digital Subscriber Loop (VDSL)format as opposed to an Asymmetric
 Digital Subscriber Loop (ADSL) format. The principal distinction between
 ADSL and VDSL is that VDSL transmission supports data rates up to
 approximately 26 Mb/s downstream to the residence 190, and 5 Mb/s upstream
 from the residence 190 over distances not exceeding 3,000 ft., while ADSL
 supports data rates of up to 9 Mb/s downstream, and up to 640 kb/s
 upstream over distances of up to 9,000 ft. Using ADSL transmission
 techniques it is possible to span distances up to 12,000 ft. with some
 reduction in the data rate.
 In the upper part of FIG. 6 a system is illustrated in which signals are
 transmitted from a telephony/XDSL linecard 353 in USAM VDSL 620 over a
 twisted wire pair drop cable 180 to the subscriber side diplex filter 420
 which separates the telephony and high speed data signals. In the
 embodiment illustrated, the analog telephony signals are transmitted from
 the subscriber side diplex filter 420 over inside twisted wire pairs 181
 to telephone 194. Data signals are transmitted over inside coaxial wiring
 171 to devices in residence 190.
 The lower portion of FIG. 6 illustrates an alternate embodiment in which
 digital signals are transmitted from a VDSL modem 354 in USAM VDSL 620
 over a twisted wire pair drop cable 180 and are received at an Active
 Network Interface Device (ANID) 610 which generates an analog telephony
 signal for transmission over inside twisted wire pairs 181 to a telephone
 194. The VDSL modem 354 and ANID 610 architecture which can provide this
 functionality are described in greater detail in FIGS. 11A and 11B along
 with the corresponding text.
 FIG. 7 illustrates an embodiment in which signals are received at residence
 190 by a subscriber side diplex filter 420 which separates the analog
 telephony signal from the digital xDSL signal using filter techniques well
 understood by those skilled in the art. From the subscriber side diplex
 filter 420 the analog telephony signals are sent over a
 point-to-multi-point in-home network based on inside twisted wire pairs
 181 and are received by telephones 194. In this embodiment, the digital
 high speed data signal is routed over a point-to-multipoint in-home
 network based on inside twisted wire pairs 181 to a variety of devices
 including a residential telephony interface unit 710, a Local Area Network
 (LAN) unit 720, a television set-top 198, and a Network Interface Card
 (NIC) 750. The residential telephony interface unit 710 serves to separate
 the Time Division Multiplexed (TDM) data which contains telephony signals
 from the digital data stream on twisted wire pair 181, and generate an
 analog telephony signal compatible with telephone 194. Set-top 198
 extracts the ATM cells containing video and set-top specific data and
 presents that information on TV 199. A remote keyboard 730 can be used
 with set-top 198 to provide computer-type functionality. LAN unit 720
 extracts ATM cells which have the address of the LAN unit 720 and permit
 the computer 193 connected to the LAN unit 720 to be connected to the
 Internet or other intranets. Similarly, NIC card 750 interfaces computer
 193 to external networks.
 FIG. 8 illustrates an embodiment in which an ANID 610 receives the high
 speed digital data from a twisted wire pair drop cable 180, and generates
 a coaxial cable compatible signal which is transmitted over inside coaxial
 cable wiring 171 to a splitter 177. Splitter 177 is of the type commonly
 used in homes today for the distribution of cable TV signals. The signals
 are routed from the splitter 177 over inside coaxial cable wiring 171 to a
 variety of devices including a Premises Interface Device (PID) 196, a
 Local Area Network (LAN) unit 720, a television set-top 198, and a Network
 Interface Card (NIC) 750.
 FIG. 9 illustrates the mechanical configuration of the Universal Service
 Access Multiplexor (USAM) 340. The USAM 340 can be rack mounted using
 brackets 910, and has redundant USAM power supply plug-ins 930. An air
 ramp 900 is used to provide cooling. There are two common control cards,
 Common Control A 932 and Common Control B 934, which interface to BDT 130
 via optical fiber 160. In a preferred embodiment the bi-directional
 optical signals sent on optical fiber 160 are in an SDH like format, at a
 rate of 155 Mb/s.
 USAM linecard plug-in units 920 are used to provide telecommunications
 services to subscribers. These linecards interface to twisted wire pair
 drop cables 180. In addition to linecards which interface to twisted wire
 pair drop cables 180 it is possible to have USAM linecard plug-in units
 920 have fiber optic interfaces and which support optical transmission
 over fiber optic cable 160. There are four general categories of linecard
 plug-in units 920, including narrowband linecards, broadband linecards,
 VDSL linecards, and ADSL linecards.
 The narrowband linecards support legacy telephony services including POTs,
 coin phone services, T1 services, ISDN services, and all of the existing
 special telecommunications services.
 Broadband linecards support Asynchronous Transfer Mode Universal Network
 Interfaces (UNIs). These UNI based broadband cards use an appropriate
 physical media which may be twisted wire pair, coaxial cable, optical
 fiber, or wireless connections.
 VDSL linecards are used to support residential broadband services over
 existing twisted wire pair drop cables 180 using VDSL transmission
 techniques, and can support transmission of traditional telephone signals
 either by generation of a POTs signal on the VDSL linecard and
 transmission with the digital VDSL signal in different portions of the
 spectrum, or by transmission of the telephone data in a digital form
 within the VDSL signal, with generation of the analog POTs signal
 occurring at the residence 190. In yet another embodiment, analog
 telephone signals can be combined with the VDSL signal in a diplexor
 external to the linecard.
 In a preferred embodiment the VDSL transmission technique used is based on
 Quadrature Amplitude Modulation (QAM) transmission techniques in which
 data is sent in multiple levels in the I and Q channels, with the number
 of levels depending on the specific characteristics of the twisted wire
 pair drop cable 180 which is being used. For poor quality drop cables, or
 where there is a large amount of radio frequency ingress, a single level
 phase inversion scheme (in both the I and Q channels) is used which
 results in a Quadrature Phase Shift Keying (QPSK) transmission, which can
 be considered equivalent to 4-QAM. For better quality transmission
 channels in high quality twisted wire pair drop cables, 16-QAM or 64-QAM
 transmission can be used.
 ADSL linecards are used to support residential broadband services using
 ADSL transmission techniques. ADSL transmission techniques are based upon
 the use of Discrete MultiTone (DMT) transmission, or QAM techniques,
 including the Carrierless Amplitude Modulation technique, commonly
 referred to as CAP, which is a method for generation of QAM signals.
 Analog telephone signals can be transmitted by the ADSL linecards in a
 manner similar to the VDSL linecards including generating the POTs signal
 on the ADSL linecard and combining it with the digital ADSL signal,
 generating the POTs signal externally and combining it with the ADSL
 signal, or generating the POTs signal at the residence 190.
 In a preferred embodiment the USAM 340 supports 16 USAM linecard plug-ins
 920. When used for VDSL and ADSL applications, there are 2 VDSL or ADSL
 circuits per USAM linecard plug-in 920, resulting in 32 VDSL or ADSL
 circuits per USAM shelf. When configured entirely with ADSL cards the USAM
 340 becomes a USAM ADSL-RT 520 or USAM ADSL-CO 510 as illustrated in FIG.
 5. When configured entirely with VDSL cards the USAM 340 becomes a USAM
 VDSL 620 as illustrated in FIG. 6. In an alternate embodiment, there are 4
 circuits per VDSL or ADSL linecard.
 When USAM 340 is configured for POTs services, there are 6 circuits per
 linecard in one embodiment, resulting in 96 circuits per USAM shelf. In
 another embodiment, there are 12 circuits per POTs linecard, resulting in
 192 POTs circuits per shelf. The USAM illustrated in FIG. 9 represents a
 single shelf, but clearly it is possible to have multiple shelves for
 greater capacity.
 In equipping USAM 340 it is also possible to mix the types of linecards to
 simultaneously provide ADSL, VDSL, and POTs services from the same
 platform. By having a cell based transport for voice and high speed data
 it is possible to support a variety of linecards simultaneously and to
 provide traditional telephone services along with high speed data
 services.
 FIG. 10 illustrates the architecture of USAM 340, and shows how Common
 Control A 932, and Common Control B 934, are connected via optical fibers
 160 to front access panel optical connectors 936. These connectors are
 connected to optical fibers 160 which are in turn connected to BDT 130. In
 a preferred embodiment, signals are sent from Common Control A 932 to USAM
 linecard plug-ins 920 via a downstream common bus A 954, and from Common
 Control B 934 to USAM linecard plug-ins 920 via a downstream common bus B
 955. Downstream common buses A and B 954 and 955 respectively are
 point-to-multipoint buses, and all of the downstream payload is received
 at all of the USAM linecard plug-ins 920. Upstream individual buses 952
 are used to transmit information from the USAM linecard plug-ins 920 to
 the Common Control A 932 and Common Control B 934.
 A Front Access Panel (FAP) connector 938 allows connection from the front
 of the USAM to an internal Front Access Panel (FAP) bus 940 which can be
 used for diagnostics.
 A Mechanized Loop Testing (MLT) bus 950 is used to allow central office
 equipment to simulate a direct connection to a particular twisted wire
 pair drop cable 180, in spite of the fact that there is actually an
 optical transmission system between the central office and the twisted
 wire pair drop cable 180. The MLT bus 950 in conjunction with circuitry on
 the POTs linecard allows central office equipment to determine the loop
 resistance and perform other key tests on a specific twisted wire pair
 drop cable 180.
 The Tip and Ring (TR) connectors 956 serve as the point of connectivity
 between the USAM linecard plug-ins 920 and the twisted wire pair drop
 cables 180. The linecard-TR connector bus 960 provides the internal
 connectivity between the USAM linecard plug-ins 920 and the TR connectors
 956.
 USAM linecard plug-ins 920 which use optical media for transmission and
 reception are connected to a front access optical connector 936 via
 optical fiber 160, or in an alternate embodiment the front access optical
 connector 936 is mounted directly on USAM linecard plug-in 920.
 FIGS. 11A and 11B illustrate an embodiment in which VDSL signals are sent
 to the residence 190 from a VDSL linecard, along with a powering signal.
 The signal is received by a unit powered from the USAM which is capable of
 both deriving data for subsequent transmission in the residence 190 over
 inside twisted wire pairs 181, or inside coaxial wiring 171, as well as
 generating an analog telephony signal.
 In FIG. 11A a combined digital telephony and data xDSL line side modem 660
 at the USAM 340 is illustrated and consists of a VDSL system Application
 Specific Integrated Circuit (ASIC) 654 which is connected to a USAM
 backplane bus connector 652, which connects to the downstream common bus A
 954, downstream common bus B 955, and upstream individual buses 952. A
 line side VDSL modem 658 is connected to the VDSL system ASIC 654 and
 generates a twisted wire pair compatible signal for transmission to the
 residence over the twisted wire pair drop cable 180. A controller 662,
 which can be any suitable microcontroller, is used to configure and
 program the VDSL system ASIC 654.
 Power is added via a power connector 650, and a current limiting circuit
 656 prevents overcurrents, and a line protection power insertion module
 664 permits the combining of the VDSL signal and the powering voltage,
 which in a preferred embodiment is -90 V and in an alternate embodiment is
 -130 V. At the twisted wire pair 180 leaving the combined digital
 telephony and data xDSL line side modem 660 a line side twisted wire pair
 with power interface 666 is formed.
 The subscriber side is illustrated in FIG. 11B, where a subscriber side
 twisted wire pair with power interface 667 is formed, and connects to a
 combined digital telephony and data xDSL subscriber side modem 661 via
 twisted wire pair drop cable 180. Signals with power are received from the
 combined digital telephony and data xDSL line side modem 660 via the
 twisted wire pair drop cable 180.
 In FIG 11B line protection 670 serves to separate the power and protect the
 subscriber side VDSL modem 674. Subscriber side VDSL modem 674 separates
 out the TDM signals containing telephony data and routes that data to a
 POTs circuit 676. The POTs circuit 676 generates an analog telephony
 signal which is routed to a twisted wire pair connector assembly 682,
 which contains a derived first line POTs connector 690, which in a
 preferred embodiment is an RJ-11 jack.
 An optional POTs/ISDN circuit 678 may be present and supports an additional
 POTs or ISDN line which can be connected via a derived second line POTs or
 ISDN connector 692 which is present in twisted wire pair connector
 assembly 682.
 In the embodiment shown in FIG. 11B, a coaxial modem 680 also receives and
 transmits digital data to subscriber side VDSL modem 674. Coaxial modem
 680 can take information from subscriber side VDSL modem 674 and generate
 a coaxial signal, which in a preferred embodiment is the Digital Audio
 Visual International Council (DAVIC) profile A type signal. The coaxial
 signal generated by coaxial modem 680 is routed to a coaxial modem
 connector 694, and subsequently to a combiner 696. The combiner 696
 permits combining of the coaxial modem signal 680 with off-air broadcast
 television signals which come from an antenna or cable TV system connected
 to off-air connector 695. The inside wiring network interface 697 has both
 the analog POTs signals and digital data signals.
 Although the embodiment illustrated in FIGS. 11A and 11B show the
 subscriber side modem and line side modem as VDSL modems, ADSL or other
 types of modems can be used to realize the invention.
 The combined digital telephony and data xDSL subscriber side modem 661 can
 also be located in gateway 200, and as illustrated in FIG. 3, a variety of
 devices can be directly connected to the gateway using twisted wire pair,
 coaxial cable, or other types of wiring.
 FIGS. 12A and 12B illustrate an alternate embodiment for transmitting
 telephony signals along with xDSL data signals. In this embodiment the
 analog POTs signal is generated on a POTS circuit 676 which is located in
 a combined analog telephony and data xDSL line side modem 760 which is
 located in USAM 340. Referring to FIG. 12A, the POTs circuit 676 generates
 an analog telephone signal which is combined with a digital data signal
 from VDSL modem 658 in the line protection POTs filter 664 which serves as
 a line side diplex filter 418. The combined analog telephony signal and
 digital data signal is present at the line side xDSL twisted wire pair
 with POTs interface 766.
 At the subscriber side, a combined analog telephony and data xDSL
 subscriber side modem 761 is used to receive the POTs and data signals. In
 a preferred embodiment, powering from the residence 190 is used via an AC
 plug 779 and power supply 668. An optional battery pack 777 can be used to
 provide power to the combined analog telephony and data xDSL subscriber
 side modem 761 in the event the AC power in the residence 190 fails. Power
 from the AC plug 779 or optional battery pack 777 is transmitted to power
 supply 668 using conventional two conductor power cable or inside twisted
 wire pairs 181.
 The combined analog telephony and data xDSL subscriber side modem functions
 for data according to the description for the data portion of the combined
 digital telephony and data xDSL line side modem 660. The line protection
 POTs filter 770 serves to separate the analog telephony signal from the
 digital data signal and serves to protect VDSL modem 674 and telephone 194
 from excessive currents.
 In the traditional approach to combining analog telephony signals with xDSL
 data signals (as shown in FIG. 4) the analog POTs signal is externally
 combined with the xDSL signal in the line side diplex filter 418. The
 principal problems with this approach are that there are two twisted wire
 pairs from the cross connect frame (the connection location for twisted
 wire pair drop cables 180 coming from the telephone central office) two
 sets of lightning protection, and unknown characteristics in terms of the
 trip ring and other impulse noise on the POTs line which could be
 detrimental to the xDSL signal. By having the POTs circuit 676 integrated
 onto the combined analog telephony and data xDSL line side modem it is
 possible to control the interference between the data signals generated by
 line side VDSL modem 658 and the analog POTs signal. This embodiment
 minimizes the amount of lightning protection required, as well as assuring
 that the impulse noise generated by the POTs circuit is characterized and
 controllable. In addition, a feeder pair from the central office is
 liberated for reuse.
 The embodiment illustrated in FIGS. 12A and 12B show the subscriber side
 modem and line side modem as VDSL modems, ADSL or other types of modems
 can be used to realize the invention.
 The combined analog telephony and data xDSL subscriber side modem 761 can
 also be located in gateway 200, and as illustrated in FIG. 3, a variety of
 devices can be directly connected to the gateway using twisted wire pair,
 coaxial cable, or other types of wiring.
 In transmitting signals to and from BDT 130 to BNU 140 over optical fiber
 160, or to and from BDT 130 to USAM 340, a frame structure based on the
 Synchronous Digital Hierarchy (SDH) standard is utilized in which the most
 significant bit (bit 1) is sent first and the least significant bit (bit
 8) is sent last. A system specific datalink channel is sent within the SDH
 frame. The SDH frame itself has 2430 bytes in a 125 .mu.s frame, divided
 into overhead areas, a 41 cell payload area and a 3 byte footer which is
 not used.
 The downstream ATM data (BDT 130 to BNU 140 or BDT 130 to USAM 340) is
 carried in a cell format illustrated in FIG. 13A, in which 4 system
 specific bytes form a downstream header 1004 which is added to a 53 byte
 ATM cell 1002. The first two bytes in the header, 1006 and 1008, are left
 unused, while the following two bytes 1010 and 1012 contain two BIU 150
 routing tags, BIU 150 routing tag high byte 1010, and BIU routing tag low
 byte 1012. An ATM Virtual Path Indicator/Virtual Channel Indicator
 (VPI/VCI)and cell header field 1014 are also present. A Header Error
 Control (HEC) field 1016 contains an error correction code word which
 covers the header 1004 and the VPI/VCI cell header field 1014.
 Upstream ATM data is carried in a cell format illustrated in FIG. 13B, in
 which 4 system specific bytes form an upstream header 1005, which contains
 two unused bytes 1026 and 1028, an ODU source ID byte 1030, and a TCAM ID
 byte 1032. An ATM VPI/VCI cell header field 1014 is also present, as is an
 HEC field 1016. An ATM cell 1002 of 53 bytes contains the ATM data.
 Time Division Multiplex (TDM) data is carried in both directions on optical
 fiber 160 (BDT 130 to BNU 140 or BDT 130 to USAM 340) as well as on the
 twisted wire pair BDT-USAM link 226 in a cell format of 57 bytes. In both
 directions, the TDM cell consists of two segments of 28 bytes and a TDM
 cell reserved byte, as illustrated in FIG. 14A, in which a 57 byte TDM
 cell is comprised of a TDM cell reserved byte 1102, a first TDM segment
 1104, and a second TDM segment 1106.
 As illustrated in FIG. 14B, the individual DSOs within the TDM segments are
 mapped into three TDM blocks of nine bytes each. A reserved segment byte
 1108 precedes a first TDM block 1110, a second TDM block 1112, and a third
 TDM block 1114.
 An asynchronous virtual tributary (VT 1.5) can be transported in a TDM
 segment as illustrated in FIG. 14C by sending one reserved VT 1.5 byte
 1116 followed by a 27 byte VT1.5 field 1118.
 The particular mapping of DSOs in a TDM block is illustrated in FIG. 15,
 where eight DSO channels are transported in bytes 2-9 (1204, 1206, 1208,
 1210, 1212, 1214, 1216, and 1218 respectively). The signaling information
 for each DS0 is transported in a signaling byte. The signaling byte is the
 first byte in the nine byte sequence which forms a frame, and each of
 eight frames carries the signaling information for one DS0 channel. As
 shown in FIG. 15, channel 1 signaling byte 1214 appears as the first byte
 of frame 1, channel 2 signaling byte 1216 as byte 1 of frame 2. Channel
 3-8 signaling bytes (1218, 1220, 1222, 1224,1226,1228 respectively) appear
 in the first byte of frames 3-8 respectively.
 An advantage of transmitting the voice and data information in an ATM
 format is that cells are routed to their destination regardless of data
 type, and no discrimination needs to be made between TDM voice signals and
 high speed data. The destination can be a BIU 150, USAM linecard plug-in
 920, ANID 610, PID 196, set-top 198, computer with NIC card 191, telephony
 interface unit 710, LAN unit 720, or gateway 200.
 The mapping of cells occurs at both the network side, where cells are
 formed from the data received from ATM network 110, and from PSTN 100, and
 at the subscriber side, where the different devices generate TDM voice
 information or high speed data. As an example, a PID 196 would generate
 TDM information and a set-top 198 or computer with NIC card 191 would
 generate high speed data. The devices in the residence or the gateway 200
 would map the information into ATM cells for transmission on the Unified
 Access Platform.
 In a preferred embodiment the mapping of TDM information into ATM cells,
 and the formation of the headers, is performed in one or more Application
 Specific Integrated Circuits (ASICs). Methods for the implementation of
 such ASICs are well known to those skilled in the art. In an alternate
 embodiment the mapping of TDM and high speed data information can be
 performed in software.
 Within BDT 130 the mapping of TDM information into cells allows for the
 efficient routing of those cells to the individual Optical Distribution
 Units (ODUs) in the BDT which generate and receive optical signals from
 BNUs 140 or USAMs 340. In a preferred embodiment there are 64 ODUs in BDT
 130. Furthermore, a BDT common control card controls the routing of cells
 to the individual ODUs in BDT 130.
 The use of ATM cells in BDT 130 and over optical fiber 160 allows voice and
 data information to be simultaneously routed from one BDT 130 to BNUs 140,
 USAM ADSL-RT 520, USAM ADSL-CO 510, and USAM VDSLs 620, where traditional
 analog telephone signals can be generated along with high speed data
 signals. Because the transmission technique and media for transmission of
 high speed data signals will vary from installation to installation, it is
 important to be able to support the various xDSL and coaxial drop cable
 networks from one Unified Access Platform.
 Although this invention has been illustrated by reference to specific
 embodiments, it will be apparent to those skilled in the art that various
 changes and modifications may be made which clearly fall within the scope
 of the invention. The invention is intended to be protected broadly within
 the spirit and scope of the appended claims.