Ulllted States Patent [19]
`Seazholtz et al.
`
`US005812786A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,812,786
`Sep. 22, 1998
`
`[54] VARIABLE RATE AND VARIABLE MODE
`TRANSMISSION SYSTEM
`
`
`[75] Inventors: John W. Seazholtz, Great Falls; Wendell NI Sims, WOOdfOrd; Kamran
`Sistanizadeh Arlington all of Va
`’
`’
`'
`[73] Assignee: Bell Atlantic Network Services, Inc.,
`Arlington, Va.
`
`[21] Appl. No.: 494,082
`_
`_
`Jun‘ 21’ 1995
`Flled'
`[22]
`[51] Int. Cl? ................................................. .. G06F 15/163
`[52] US. Cl. ............................... .. 395/200.63- 395/200.81
`I58] Field of Search
`395/260 01 200 6
`""""""""""""" "395/200 '63 ’200
`'
`’
`'
`
`[56]
`
`References Cited
`
`US. PATENT DOCUMENTS
`3/1981 Herschtal et al
`
`370/465
`455/41
`8/1989 Schoeneberger et a1.
`____ __ 379/94
`9/ 1989 HeinZelmann ......... ..
`370/276
`5/1993 Renner et a1_
`..... .. 348/7
`9/1993 Litteral et a1.
`8/1994 Gelman et al. .................. .. 395/200.09
`
`4 258 433
`
`4,860,379
`4,866,758
`572147650
`5,247,347
`5,341,474
`
`9/1994 Moura et a1. ........................... .. 348/ 12
`5,347,304
`5,365,264 11/1994 Inoue et a1.
`348/70
`5,371,532 12/1994 Gelman et a1. .
`348/7
`
`,
`,
`
`?ns?“ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ll rapa I18. ........................... .. ~ ~
`
`5,594,726
`1/1997 Thompson .............................. .. 370/85
`5,613,190
`3/1997 Hylton ................................... .. 455/31
`Primary Examiner—Eric Coleman
`Attorney, Agent, or Firm—IJoWe, Price, LeBlanc & Becker
`[57]
`ABSTRACT
`
`A public switched telephone network (PSTN) provides
`communication of digital data from a data provider or LAN
`to one Or more of a plurality of subscriber premises Asym
`metrical digital Subscriber line interface units Operating at
`variable rates and in variable modes (ADSL/AVRs) over a
`local loop offer one-Way video-on-demand and other ser
`vices and carry the necessary signalling betWeen the sub
`scribers and information providers. In an asymmetric mode,
`the interface units frequency multiplex digital information
`With voice information to the subscriber and support trans
`mission of a reverse control channel from the subscriber to
`the central office for transmission back to the information
`_
`.
`.
`.
`provider. Other modes are supported WhlCh perm1t selective
`bi-directional and reversible communications as Well.
`
`26 Claims, 8 Drawing Sheets
`
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`Netflix 1028 - Page 1
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`U.S. Patent
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`Sep. 22, 1998
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`Sep. 22, 1998
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`Netflix 1028 - Page 5
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`Sep. 22, 1998
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`U.S. Patent
`
`Sep. 22, 1998
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`Sheet 7 of 8
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`Netflix 1028 - Page 8
`
`

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`U.S. Patent
`
`Sep. 22, 1998
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`Netflix 1028 - Page 9
`
`

`
`1
`VARIABLE RATE AND VARIABLE MODE
`TRANSMISSION SYSTEM
`
`TECHNICAL FIELD OF THE INVENTION
`
`The invention relates to a transmission system for trans
`mitting video or other information over a netWork, and more
`particularly to a transmission system for efficiently, selec
`tively and interactively transmitting video and other infor
`mation over a single tWisted copper Wire pair in the Public
`SWitched Telephone NetWork (PSTN) at a variable rate or in
`a variable mode.
`
`BACKGROUND OF THE RELATED ART
`It has recently become possible to provide Wired trans
`mission of full-motion digitized video programming, rather
`than still frame or limited video conferencing, Without the
`use of dedicated leased, Wide bandWidth circuits and T1
`lines. In particular, it has become possible to provide for the
`cost effective routing and distribution of a large amount of
`video or other data at high speed and in real time using the
`existing copper plant. For example, US. Pat. Nos. 5,341,474
`and 5,371,532 to Gelman et al discuss a “store-and-forWard”
`architecture and method for distributing information to
`subscribers and US. Pat. No. 5,247,347, issued to L. Litteral
`et al on Sep. 21, 1993 and assigned to the assignee of the
`present invention, discusses a method of providing video
`on-demand (VOD) services With VCR type functional con
`trol of the programming.
`In the systems discussed in these three patents, a menu of
`programming information is accessible at the subscriber’s
`premises. The subscriber may transmit order requests via the
`PSTN to the independent information providers. Informa
`tion programs may be accessed and transmitted to the
`subscriber directly from an information provider or through
`a video buffer located at a central of?ce (CO) serving the
`subscriber.
`The information provider transmits coded digital data
`over Wideband PSTN to a central of?ce. The data may be
`buffered at the central office for transmission over a POTS
`(plain old telephone service) line to the subscriber using a
`video gateWay. An access concentrator/packet sWitch at the
`central office receives the order request from the subscriber
`loop. A video gateWay in turn is responsive to the order
`request for producing routing data. A ?le server, responsive
`to requests received from the video gateWay, obtains
`selected information from the digital information storage
`medium. A circuit or ATM cross-connect sWitch in turn is
`responsive to the routing data for transferring the informa
`tion from the ?le server to the subscriber loop transmission
`means.
`A subscriber in such a system may use either a standard
`telephone instrument over the PSTN or a dedicated control
`device over an X.25/ISDN packet netWork to order the
`information program. The dedicated control device is either
`a settop box Which is located at a television set of the
`subscriber and Which permits a display of the program menu
`on the television screen or a computer With appropriate
`control boards.
`Connectivity betWeen the central of?ce and the subscriber
`for transmission of data is provided by one of a number of
`different interface units, such as an asymmetrical digital
`subscriber line (ADSL) interface or a high bit rate digital
`subscriber line (HDSL) interface. ADSL systems are gen
`erally preferable to bi-directional HDSL systems for ser
`vices such as video-on-demand in Which the amount of
`information transmitted in one direction is much greater than
`
`10
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`15
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`5,812,786
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`2
`the amount of information transmitted in the opposite direc
`tion. ADSL systems provide a cost effective and bandWidth
`ef?cient platform for receiving or transmitting a large vol
`ume of information at high speed in a single direction using
`the existing copper plant. An asymmetrical communication
`transport provides high bandWidth for fast transfer of bulk
`data in one direction, While a sloW transmission rate is used
`for bi-directional communication. Typically, a request for
`data requires very little data transfer in the upstream direc
`tion and the data delivery involves high data traf?c in the
`doWnstream direction. In addition, ADSL systems are gen
`erally capable of transmitting over longer distances than
`HDSL, do not interfere With POTS or ISDN communica
`tions and therefore require only a single copper pair.
`T1 communication enables simultaneous high speed digi
`tal transmission of bulk data in both directions, but requires
`special Wiring and circuitry and exceeds requirements for
`data netWork applications in Which high bulk data transfer
`occurs only in one direction at a time. Existing video
`conferencing transceivers and HDSL systems permit
`bi-directional transmission at high bit data rates.
`The data rates of the channels in conventional ADSL
`systems are typically predetermined according to the struc
`ture of the ADSL interface units. Therefore, although pre
`vious systems may be Well suited for some services such as
`video-on-demand, they are not Well suited for other services
`in Which the nature and amount of data and control signal
`transfer is substantially different or changes frequently.
`Speci?cally, the tWo-Way control channel may be unaccept
`ably sloW for services such as interactive multi-media,
`distance learning, or accessing a server in a remote local area
`netWork (LAN) over a POTS line using a single copper pair.
`One or more of these services may require a bi-directional
`control channel of up to, for example, 384 kbps in order to
`alloW substantially real-time communications so that a sub
`scriber is not Waiting for information to be transmitted.
`Furthermore, systems Which provide services such as
`video-on-demand and home shopping typically only provide
`for the transfer of video programming or other data in a
`single direction from a VIP or other information provider to
`a subscriber. They may not provide signi?cant bi-directional
`capability, full connectivity amongst all of the subscribers on
`the netWork, or multi-cast transmission capability Which can
`be point-to-point or point-to-multipoint for distance
`learning, video phone etc.
`SUMMARY OF THE INVENTION
`Accordingly, it is a broad object of the invention to
`controllably operate in one of a plurality of different modes
`and at any one of a plurality of different bit rates so as to
`provide a single transmission platform Which may support a
`plurality of different services, including but not limited to,
`video on demand and reliable bi-directional communica
`tions at data rates greater than 16 kbps.
`Another object of the invention is to provide an asym
`metrical ?oW of information Wherein the direction of the
`asymmetrical How of information can be simply and easily
`reversed.
`Still another object of the invention is to simply and easily
`vary the bit rates of the upstream and doWnstream channels,
`or the modes of the transceivers, of an ADSL netWork.
`Another object is to either automatically control bit rate or
`mode by the CO or selectively control bit rate or mode by
`the subscriber.
`Afurther object of the invention is to provide a high speed
`reversible channel for receiving and sending unidirectional
`data/video.
`
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`

`
`3
`Still another object is to provide a truly bi-directional
`fractional T1 service using a transceiver that transmits only
`a fractional T1.
`It is a further object of the invention to provide a full
`service information netWork over the existing copper plant
`of telephone Wires by connecting to a computer netWork and
`performing format conversion and multi-cast transmission
`in real time.
`In order to achieve the above objects, this invention adds
`10
`capabilities to present netWorks by providing an ADSL
`having adjustable variable rate functionality (ADSL/AVR).
`A controllable transceiver in the ADSL/AVR alloWs the
`communication rate to be selected from 2x64 KB up to 1.5
`Mb/s or 6.2 Mb/s into a digital cross connect system or ATM
`edge device or sWitch. Such a netWork has the advantages of
`conventional ADSLs, While alloWing the data rate of the
`reverse control signaling channel to be controllably
`increased so as to have a higher rate transmission than ADSL
`in a bi-directional mode.
`A preferred embodiment of the invention uses a termi
`nating unit Which has a T1 interface on one side and a
`variable rate interface on the other side. A digital cross
`connect system has at least one 1/1 cross-connect to cross
`connect T1s and a plurality of 1/0 cross connects to cross
`connect fractional parts of T1s (DSOs) in order to aggregate
`or groom services in the backbone netWork betWeen the 1/0
`DCSs and provide more ef?cient transport across the net
`Work.
`Other embodiments of the invention use an ATM, Frame
`Relay, or SMDS netWork at the central of?ce end. Ethernet
`interfaces are used to facilitate transport to a personal
`computer at the remote end and LAN/WAN connections to
`ATM, Frame Relay, or SMDS sWitching at the central office
`end.
`This variable rate/variable mode ADSL service Will
`accommodate access to a Wide variety of information pro
`viders such as the Internet or other data netWorks through
`Which data from servers are to be retrieved. The service has
`applicability in various contexts such as telecommuting and
`banking services. The ADSL service can also be used in an
`of?ce building LAN or betWeen house pairs.
`In addition to variable bit rates for the control channel, the
`invention enables at least tWo modes for the ADSL
`transceivers, one providing bi-directional communications
`45
`and the other providing asymmetrical communications such
`as video-on-demand. Each ADSL transceiver is either a
`discrete multi-tone (DMT), CAP or DWMT transceiver
`comprising identical programmable chip sets in Which dif
`ferent ?rmWare may be doWnloaded to enable the different
`rates and different modes.
`In accordance With a further aspect of the invention, the
`transmission bit rate may be asymmetrical in selectively
`changeable directions so that parties to a communication
`session can individually exchange bulk data transmission in
`both directions. The ADSL transceivers may be responsive
`to a control signal transmitted in the upstream channel Which
`indicates that the direction in Which data is transmitted
`should be reversed.
`The above and other objects, features and advantages of
`the present invention Will become apparent from the fol
`loWing description taken in conjunction With the accompa
`nying draWings.
`BRIEF DESCRIPTION OF DRAWINGS
`FIG. 1 is a system diagram of a ?rst preferred embodi
`ment of the invention shoWing connection betWeen a video
`
`4
`server, a local area netWork and a single subscriber through
`a digital cross connect and tWo ADSL/AVRs.
`FIG. 2 is a system diagram of a second embodiment of the
`invention shoWing connection betWeen a video server/ATM
`Edge device and a single subscriber through an ATM sWitch
`and tWo ADSL/AVRs.
`FIG. 3 is a functional diagram of a conventional asym
`metrical digital subscriber line unit (ADSL).
`FIG. 4 is a frequency domain diagram shoWing the preset
`channeliZation of a local loop in a system using the con
`ventional ADSL of FIG. 3.
`FIG. 5 shoWs a typical in-the-home con?guration provid
`ing video transported over a 1.544 MBPS channel overlaid
`With standard telephone service signaling in the system
`using the conventional ADSL of FIG. 3.
`FIG. 6 is a hardWare block diagram of the conventional
`ADSL of FIG. 3 con?gured to provide simplex high-bit-rate
`access and POTS on a common copper loop.
`FIG. 7 is a hardWare block diagram of a con?guration in
`Which an ADSL/AVR is used to provide variable rate and
`variable mode service on top of POTS on a common copper
`loop.
`FIG. 8 is a diagram of a conventional video decoder unit
`resident at the subscriber’s premises.
`FIG. 9 is a block diagram of a preferred embodiment of
`the ADSL/AVR DMT transceiver used in the present inven
`tion.
`FIG. 10 is a frequency domain diagram shoWing an
`example of the possible channeliZation of a local loop in a
`system in When the ADSL/AVR transceiver of the present
`invention is operating in a bi-directional mode.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`A ?rst preferred embodiment of the invention shoWn in
`FIG. 1 utiliZes existing components of the Public SWitched
`Telephone NetWork (PSTN) to access video programs from
`a video server 20 in a video-on-demand service or data
`through a private local area netWork (LAN) 30. The sWitch
`ing facilities are located in a central of?ce (CO) 10 serving
`residential customers or other subscribers. Loop electronic
`devices modify the transmission characteristics of the local
`copper loop as necessary to provide required enhancements
`to the PSTN and/or permit high bit rate delivery of full
`motion video or other information.
`Video Server 20 implements compression techniques to
`store video and other information for subsequent forWarding
`over interof?ce facilities in a video-on-demand service, such
`as that disclosed in US. Pat. No. 5,247,347 and hereby
`incorporated by reference, in Which analog video informa
`tion is ?rst converted to a digital format using standard
`encoding techniques such as MPEG.
`Video server 20 may also process information and serve
`information other than video information, such as still
`pictures, audio, interactive video, including interactive
`learning, interactive games, and other presentations some
`times termed “multi-media.” The server may also store and
`process all data required for video ?le and other media
`applications including text, still pictures, audio, and partial
`and full motion video, as Well as interactive application
`scripts.
`In addition to storing pre-encoded video ?le information,
`video server 20 may also accept live video feeds and other
`media ?le programming from other servers for later trans
`mission or for real-time and multi-pass encoding in an
`
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`encoder (not shown). Real-time encoding is used to provide
`encoded high bandwidth signals, such as full motion live
`action video, in real time While minimizing network trans
`mission requirements and providing a signal compatible
`With ADSL connectivity to subscriber premises 40. Multi
`pass encoding performed by the ?le servers provides a
`higher quality video signal for storage and later transmission
`over the netWork to subscriber premises 40 than is possible
`With single-pass encoding.
`The netWork control softWare of the server in combination
`With management resources of the PSTN control the “net
`Work session” betWeen an output controller of the ?le server,
`external program providers, and user ports. An associated
`session manager also maintains a record of relevant data
`regarding each session Which is forWarded to a customer
`billing system. Video and other media ?le data from the
`server are provided to the CO and selectively supplied to
`subscribers under control of netWork controller 11, level 2
`gateWay 16, level 1 gateWay 17, and signalling and control
`netWork 18.
`A control server (not shoWn) in video server 20 keeps
`track of all information, and routes the movies and other
`video programs to subscribers at an appropriate port through
`a high bandWidth interface. The control server has a large
`number of ports, each port controlling a single transmission
`to one or more subscribers sharing the session (vieWing a
`movie). The state of each port is knoWn by a table stored in
`the control server.
`Upon receipt of an order from the level 2 gateWay 16, the
`control server bundles the order With other identical orders
`received recently, and assigns a port based on the states read
`from the table. For example, a particular port Will be
`reserved for all subscribers placing the same order Within the
`next ?ve minutes. Conversion betWeen the telephone num
`ber of the subscriber and frame address for establishing a
`physical connection through the DCS is carried out by a
`look-up table in a data base of the level 2 gateWay 16. Level
`2 gateWay 16 may be implemented by any one of number of
`different available equipment suitable for that purpose
`including, but not limited to, a IBM RISC 6000 computer
`supplied With catalog information of the ?les available from
`video server 20.
`The ?le server processes all requests from the gateWay to
`provide video ?le and video ?le feeds to customer premises
`via the CO and ADSL/AVR interfaces. The ?le servers
`perform input of video and other information ?les, store
`these ?les or pass real-time data through to subscriber
`premises 40, monitor and record user sessions, process
`interactive control requests from users, and control outputs
`to the users. A session supervisor manages all program
`sessions including system access by subscribers, other video
`?le users and input and output to, from and through the ?le
`server by multi-?le information providers. The session
`supervisor tracks and records all data considered pertinent to
`a user’s session including output port, input port, ?le
`address, ?le index data, ?le frame data, and sessions con
`dition. The session supervisor also performs netWork
`resource optimiZation by the simultaneous broadcast of the
`same ?le over one output port to multiple subscribers.
`HoWever, each subscriber session is individually managed to
`permit interactive features such as video pause.
`Asession trace processor tracks each subscriber’s session
`based on ?le and frame so that the execution of a pause
`sequence can be managed for each individual session. A
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`subscriber may start vieWing a ?le individually or as part of
`a larger group. Selection of a pause function places the
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`subscriber “out of sync” With the rest of the group and,
`hence, requires establishment of a separate session for that
`user and causes level 2 gateWay 16 to establish a neW
`netWork link to the subscriber’s vieWing location. Although
`each user is assigned an individual logical session, sessions
`in sync With one another can share output and netWork
`facilities.
`Dial-up access to video server 20 is provided by a voice
`sWitch Which establishes connectivity With a voice recog
`nition unit (VRU) Which ansWers the incoming call and
`prompts the subscriber for a user ID Which is input via the
`DTMF pad of a telephone. The user ID is checked and, if
`valid, the VRU prompts for a selection. The selection is then
`input using the DTMF pad of the telephone Which then sends
`the selection information to the ?le server via the level 1
`gateWay and level 2 gateWay. The ?le server identi?es the
`requested ?le and determines if the ?le is available and notes
`any vieWer restrictions.
`If the ?le is found, is not restricted from the requestor and
`has not been previously queued for transmission, it is opened
`and a reserve idle communications port is identi?ed for
`transmission of the data to the CO. Transmission of the data
`is delayed for a predetermined number of minutes in
`response to a ?rst request to alloW for simultaneous trans
`mission of the data ?le to subsequent subscribers placing an
`order Within the delay period. The subsequent request orders
`are also placed in the queue and the associated communi
`cations port ID is matched to the subscriber’s netWork
`address.
`After expiration of the predetermined delay, i.e., When
`current time equals the designated start time, the data ?le is
`transmitted from ?le server through the DCS to the desig
`nated ADSL/AVRs for transmission to subscriber premises
`40. At the end of the program, a message is transmitted by
`the server to netWork controller 11 to take the system doWn
`by terminating DCS connectivity.
`30 such as an
`A standard local area netWork
`Ethernet LAN With associated ?le server 31 and Workstation
`32 provides and receives data through a router (not shoWn)
`and LAN interface unit 33. A T1 MUX, HDSL or an
`ADSL/AVR interface 34 connects the LAN to a T1 MUX,
`HDSL or an ADSL/AVR interface 36 in CO 10 in any one
`of three corresponding modes via local loop 35. The HDSL
`interface may contain multiple fractional T1 interfaces (not
`shoWn) Which utiliZe different portions of the T1/E1 band
`Width may also be used to provide connectivity With the
`central of?ce. Furthermore, some form of ?ber extension
`may be utiliZed in local loop 35, to provide reliable over
`distances of more than about 1.5 kilo-feet from central office
`10 (see, e.g., US. patent application Ser. No. 08/233,579, in
`the name of Bruce Kostreski, ?led Apr. 26, 1994, and
`entitled “Extended Range Video On Demand System”). In
`the illustrated netWork, the connection is a Wired ADSL
`loop.
`The subscriber’s premises 40 are preferably provided With
`a telephone 41, television 42, set top box 43, remote control
`unit 44 and personal computer 45. Although a personal
`computer is illustrated, any user station Which processes
`data may be used by the subscriber and connected to the
`netWork. Remote control 44 can be a conventional infrared
`remote control for sending commands to, and otherWise
`interacting With, set top box 43. Data from set top box 43 is
`provided to the subscriber side ADSL/AVR 46 or, although
`not shoWn, to a decoder for transmission of command data
`to ISDN D-channel or X25 interface. The set top box 43 can
`provide subscriber order information directly to level 2
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`gateway 16 in lieu of a voice response unit. The ADSL/AVR
`interface 46 preferably contains a toggle sWitch Which can
`control the direction of an incoming and outgoing signals to
`either the set top box 43 or personal computer 45.
`The subscriber’s premises are connected to CO 10 via
`subscriber side ADSL/AVR unit 46, CO side ADSL/AVR
`unit 48 and local subscriber loop 50. The ADSL/AVR units
`are similar to each other in structure and constitute an
`improvement over conventional ADSL units as described in
`detail beloW. Again, some form of ?ber extension may be
`utiliZed in local subscriber loop 50, to provide reliable
`connections over distances of more than about 1.5 kilo-feet
`from central of?ce 10 (see, e.g., US. patent application Ser.
`No. 08/233,579, in the name of Bruce Kostreski, ?led Apr.
`26, 1994, and entitled “Extended Range Video On Demand
`System”) now US. Pat. No. 5,534,912. In the illustrated
`netWork, connection 50 is a Wired ADSL loop.
`Once gateWay 16 identi?es a subscriber request to estab
`lish connectivity betWeen the subscriber and video server
`20, the address of control unit 44 is provided to the video
`server. Upon receipt of the corresponding netWork address
`by control unit 43, direct connectivity is established betWeen
`control unit 43 and video server 20 over packet data netWork
`50. This connectivity permits direct data transfer betWeen
`the customer premises and the associated VIP to support
`interactive video control used in interactive educational
`programming and interactive video presentations such as
`video games. Control unit 43 provides user interactive
`control of the buffered video data.
`Plain old telephone service (POTS) is separately provided
`to the subscriber in a conventional manner through POTS
`sWitch 19 and ADSL/AVR interface 48 so that if the poWer
`goes out, the telephone service still Works. The operations of
`establishing and monitoring connections linking the video
`server 20 and LAN 30 With subscriber’s premises 40 receiv
`ing and sending information is performed by a supervisory
`netWork controller 11 Which controls electronic digital
`cross-connect sWitches 12, 13, 14 and 15 that reside in CO
`10. The netWork controller preferably establishes a path to
`the loop transport system based on a predetermined set of
`options. This alloWs for video or demand as Well as other
`high bit rate data communications over the ADSL/AVR
`interface units. If symmetrical, the 1/0 cross connect is used.
`With speci?c instructions to set up and tear doWn the
`connection as required, the 1/0 controller provides router
`functionality. An example of a suitable netWork controller is
`a netWork management softWare package such as the Mega
`Hub BASiSTM Controller by Digital SWitch Corporation.
`SWitching of the doWnstream T1 rate traf?c may be
`effected through suitable cross connect circuit sWitches such
`as the Digital Access and Cross-connect System (DACS) by
`AT&T or the Dexes product by Digital SWitch Corporation
`placed betWeen the hub and the ADSL/AVR unit. SWitching
`may also be effected through packet sWitching. Each of the
`1/1 DCS’s 12 and 13 are tWo-Way T1 capable and adapted
`to provide bridging or broadcasting of video or other infor
`mation to several subscribers. The multiplexing of fractional
`T1s in each of the 1/0 DCS’s 14 and 15 is controlled by
`netWork controller 11 and is carried out When less than an
`entire DS1 is to be transmitted through the inter office
`netWork (IOF) if it can be combined With other fractional
`services and pumped over the netWork as full groups of T1.
`Fractional HDSL transmission systems With multiple frac
`tional T1 interfaces to utiliZe different portions of the T1/E1
`bandWidth may also be used to provide connectivity
`betWeen the central office and the subscriber.
`Although a single user is shoWn in FIG. 1, it should be
`understood that there may be a large number of users in the
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`netWork, each one having an ADSL/AVR interface con
`nected to one of a plurality of ADSL/AVR interface units
`Within the CO. The ADSL/AVR interface units at the central
`of?ce may be shared by multiple users using a netWork
`management system. (Alternatively, the CO may have a
`router With ADSL functionality built in.) In that case, each
`of the channels can be combined With others in the 1/0 DCS
`15 serving the homes or the 1/0 DCS 14 on the LAN end and
`thereby connected to the LAN over a single T1 link. Once
`connection to the LAN is established, the netWork capabili
`ties are used to combine fractional T1s With others to get
`economies across the netWork directed to the LAN.
`Alternatively, a bandWidth manager may be provided for
`grooming the data from adjusting multi-rate services above
`the DS0 level for individual customers.
`The ADSL/AVR’s used in the present invention are a
`modi?cation of, and an improvement over, conventional
`ADSL units such as those shoWn in FIGS. 3 and 6. Con
`ventional ADSL units carry out error correction and multi
`plex
`voice and signaling information and (ii) digital video
`or other information on subscriber loop 50 using frequency
`multiplexing to divide the available loop bandWidth into
`three channels 302, 304 and 306 (see FIG. 4), including a
`large (i.e., 1.544 Mbps) one-Way data channel doWnstream
`to the subscriber and a small (i.e., 16 or 64 kbps) tWo-Way
`reverse control channel upstream on the ISDN packet data
`netWork betWeen the subscriber and the central of?ce.
`Base band audio and signaling beloW 4 kilohertZ (kHZ)
`provide connectivity for conventional telephone services
`available on the “plain old telephone system” (POTS).
`Alternatively, ISDN channel requirements could consume
`the bottom 80 kHZ of loop bandWidth. Reverse channel
`digital packet information, centered on 95 kHZ, provides 8
`kilobits per second (kbps) of handshaking protocol betWeen
`the customer- and trunk-side ADSLs to test the copper pair
`transmission path, and