Digital loop carrier remote terminal having integrated digital subscriber plug-in line cards for multiplexing of telephone and broadband signals

• US 6,480,487 B1
• Filed: 08/24/1998
• Issued: 11/12/2002
• Est. Priority Date: 08/24/1998
• Status: Expired due to Fees

• Current Assignee: Verizon Patent and Licensing Incorporated (Verizon Communications Inc.)
• Original Assignee: Verizon Services Group (Verizon Communications Inc.)
• Inventors: Brooks, Kenneth R., Wegleitner, Mark A.
• Primary Examiner(s): MARCELO, MELVIN C
• Application Number:
  US09/138,406
• Time in Patent Office: 1,541 Days
• Field of Search: 370/493, 370/494, 370/495, 370/352-356
• US Class Current: 370/354
• CPC Class Codes: H04M 3/005 Interface circuits for subscriber lines current supply H04M19/00 and subgroups; supervisory, monitoring or testing arrangements H04M3/22 and subgroups; in key telephone systems H04M9/006
• CPC Class Codes: H04M 3/007 Access interface units for simultaneous transmission of speech and data, e.g. digital subscriber line [DSL] access interface units DSL access multiplexers H04Q11/0478, and H04L12/2856

Abstract

A fiber-based digital loop carrier (DLC) system provides multiplexed optical transport for telephone line circuits between a terminal in a central office and a remote terminal. The remote terminal performs the multiplexing and demultiplexing for interfacing channels on the fiber(s) to individual subscriber line circuits. To expand the capacity of DLC systems to carry broadband services, fibers are run from broadband terminations in the central office to the remote terminal. The remote terminal includes interfaces for coupling to optical fibers, for two-way telephone communications and for broadband communications. This terminal also includes a line card rack, for mounting various line cards and providing appropriate connections of the cards to the channels through the fiber interfaces. Some of the line cards provide normal telephone type service connections for one or more telephone lines. One or more of the line cards supports xDSL technology, for example Asymmetric Digital Subscriber Line (ADSL) type service. An ADSL line provides multiplexed transport of two-way telephone service signals, and one or more downstream and corresponding upstream digital broadband channel. The ADSL line card connects to one or more narrowband channels for telephone service and signaling communications and connects to a broadband channel, through backplane buses of the remote terminal. The ADSL line card also performs the digital encoding and multiplexing/demultiplexing of the narrowband and broadband communications for transport over a wire pair together with analog or ISDN type telephone signals.

Claims

1. A remote terminal for providing communication between a central office and subscriber premises equipment within a prescribed serving area, the remote terminal comprising:

a first bus for carrying digitally multiplexed narrowband data channels to and from the central office;

a second bus for carrying digitally multiplexed broadband data channels;

a set of first subscriber line circuits, connected to the first bus, for logically connecting first subscriber loops serving a first group of subscribers to the narrowband data channels;

a set of second subscriber line circuits, connected to the first bus and the second bus, for logically connecting second subscriber loops serving a second group of subscribers to the narrowband data channels and the broadband channels; and

a terminal controller for controlling logical connections between the first subscriber loops and the narrowband data channels, and between the second subscriber loops and the narrowband data channels and the broadband channels.

2. The remote terminal of claim 1, further comprising:

an optical interface for receiving an optical fiber carrying narrowband data on the narrowband channels from the central office;

a time slot interchange for selectively outputting the narrowband data received by the optical interface to the first bus; and

a broadband data interface configured for selectively passing broadband data units, based on the respective addresses, between a broadband source and the second bus.

3. The remote terminal of claim 2, wherein the broadband data interface includes an Asynchronous Transfer Mode (ATM) switch receiving the broadband data units as ATM cells from the broadband source, the ATM switch selectively passing the ATM cells to the second bus based on the respective virtual addresses.

4. The remote terminal of claim 3, wherein each of the second subscriber line circuits comprises:

a plurality of telephone line interface units, each converting digital words received from a selected one of the narrowband channels at a prescribed time slot into a first downstream analog signal at a first prescribed frequency range for the corresponding second subscriber loop and converting first upstream analog signals received from the corresponding second subscriber loop at the first prescribed frequency range to digital words for upstream communication on one of the first and second busses;

a synchronous multiplexer/demultiplexer circuit for logically connecting selected narrowband data channels on the first bus to the telephone line interface units, respectively;

an ATM terminal adapter for outputting digital data recovered from selected ATM cells on the second bus based on a prescribed group of virtual addresses;

a plurality of digital subscriber loop modems, each modulating the corresponding digital data output from the ATM terminal adapter into a second downstream analog signal at a second prescribed frequency range and demodulating a second upstream analog signal at a third prescribed frequency range from the corresponding second subscriber loop into an upstream digital signal; and

a plurality of combiner circuits, multiplexing the corresponding first and second downstream analog signals into a combined subscriber signal onto the corresponding second subscriber loop, and demultiplexing the first and second upstream analog signals to the corresponding telephone line interface unit and digital subscriber loop modem, respectively.

5. The remote terminal of claim 4, wherein each of the second subscriber line circuits further comprises a line circuit controller in communication with the terminal controller, for controlling the logical connections between the synchronous multiplexer/demultiplexer circuit and the first bus, and the logical connections between the ATM terminal adapter and the second bus.

6. The remote terminal of claim 5, wherein the terminal controller supplies logical connection data to each of the line circuit controllers to establish the logical connections between the second subscriber line circuits and the first and second busses.

7. The remote terminal of claim 3, wherein the set of first subscriber line circuits includes at least one of POTS subscriber line cards and ISDN subscriber line cards.

8. The remote terminal of claim 3, wherein each of the second subscriber line circuits are configured for outputting first narrowband subscriber data, received from the corresponding second subscriber loop on a two-way telephone channel and representing voice data, to the first bus and for outputting second narrowband subscriber data, received from the corresponding second subscriber loop on an upstream data channel and representing non-voice data, to the second bus.

9. The remote terminal of claim 8, wherein each of the second subscriber line circuits identifies data received from the corresponding second subscriber loop as one of the first narrowband subscriber data and second narrowband subscriber data based on a corresponding frequency range on the second subscriber loop.

10. The remote terminal of claim 8, wherein the second narrowband subscriber data is output by the ATM switch to the broadband source.

11. The remote terminal of claim 1, wherein each second subscriber line circuit provides a two-way communication interface between at least one corresponding subscriber premises equipment and the central office, and another two-way communication interface between the at least one corresponding subscriber premises equipment and a broadband source supplying broadband data to the remote terminal on one of the broadband data channels.

12. A remote terminal for providing communication between a central office and subscriber premises equipment within a digital loop carrier serving area, the remote terminal comprising:

digital subscriber line circuits, each receiving digitally multiplexed narrowband data channels from the central office and digitally multiplexed broadband data channels from a broadband data source, each digital subscriber line circuit configured for selectively establishing a two-way narrowband data connection between the central office and at least one corresponding subscriber loop on a corresponding selected one of the digitally multiplexed narrowband data channels, and a two-way communication interface between the at least one corresponding subscriber loop and a broadband data source on one of the digitally multiplexed broadband data channels; and

a controller for logically controlling establishment of the two-way narrowband data connections and the two-way communication interfaces by the digital subscriber line circuits.

13. The remote terminal of claim 12, wherein each digital subscriber line circuit comprises:

a plurality of telephone line units, each configured for establishing the two-way narrowband data connection for the corresponding subscriber loop;

a broadband terminal adapter for selectively establishing the two-way communication interfaces by outputting broadband data streams for the subscriber loops corresponding to said each digital subscriber line circuit, the broadband terminal adapter selectively outputting the broadband data streams from the bus based on a prescribed group of virtual addresses and supplying, to the bus, upstream data from the corresponding subscriber loops; and

a plurality of digital subscriber loop modems, each outputting to the corresponding subscriber loop a first modulated analog signal carrying the corresponding broadband data streams and recovering the upstream data from a second modulated analog signal supplied by the corresponding subscriber loop.

14. The remote terminal of claim 13, wherein the digital subscriber loop modems are Asymmetrical Digital Subscriber Line (ADSL) modems.

15. The remote terminal of claim 12, wherein the digital subscriber line circuits are implemented as integrated Asymmetrical Digital Subscriber Line (ADSL) plug-in cards, each serving a plurality of the subscriber loops and comprising:

at least one of a POTS line circuit and an ISDN line circuit providing the two-way narrowband data connection for each of the subscriber loops, and

ADSL modems for modulating broadband data from the two-way communication interfaces onto the respective subscriber loops and outputting to the two-way communication interfaces narrowband upstream data obtained from the respective subscriber loops.

16. A multichannel information distribution system for supplying communication between a central office and subscribers in a digital loop carrier serving area, the system comprising:

a first set of optical fibers carrying digitally multiplexed voice channels from the central office;

a second set of optical fibers carrying digitally multiplexed broadband data channels from a broadband source;

a remote terminal connected to the first and second sets of optical fibers, the remote terminal having digital subscriber line circuits, each digital subscriber line circuit establishing a two-way connection between at least one subscriber premises equipment and the central office, a downstream broadband connection between the broadband source and the corresponding at least one subscriber premises equipment, and an upstream data connection between the at least one subscriber premises equipment and an information provider supplying broadband data via the corresponding downstream broadband connection; and

a plurality of subscriber loops, each carrying signals between the remote terminal and the corresponding subscriber premises equipment associated with the two-way connection, the downstream broadband connection, and the upstream data connection.

17. The distribution system of claim 16, wherein the digital subscriber line circuits are implemented as integrated Asymmetrical Digital Subscriber Line (ADSL) plug-in cards, each having at least one of a POTS line circuit and an ISDN line circuit providing the two-way connection, and an ADSL modem for modulating broadband data from the downstream broadband connection onto the corresponding subscriber loop and outputting to the upstream data connection the data received from the corresponding subscriber loop for the service provider.

18. A method of providing communication between a central office and central office subscribers in a digital loop carrier serving area, the method comprising:

receiving, by a remote terminal serving the central office subscribers, digitally multiplexed voice channels from the central office via an optical fiber;

receiving digitally multiplexed broadband data channels by the remote terminal; and

selectively establishing in an integrated remote terminal line card, for each subscriber loop serving a corresponding subscriber premises equipment, at least one of a two-way communication interface between the corresponding subscriber premises equipment and the central office, a downstream broadband connection for supplying broadband data from one of the broadband data channels to the corresponding subscriber loop, and an upstream data connection for outputting data received from the corresponding subscriber loop to a service provider supplying the broadband data.

19. The method of claim 18, wherein the step of receiving digitally multiplexed broadband data channels comprises receiving, via a second optical fiber, the multiplexed broadband data channels as ATM cell streams.

20. The method of claim 18, wherein the selectively establishing step comprises establishing a telephone connection between the central office and the corresponding subscriber premises equipment via the corresponding subscriber loop by:

detecting a call from the central office on an identified one of the digitally multiplexed voice channels;

outputting data from the one identified voice channel to one of a plurality of subscriber loop interfaces on the integrated remote terminal line card, the subscriber loop interfaces sending and receiving telephone signals to the subscriber loops, respectively; and

outputting a telephone signal, representing the output data from the one identified voice channel, from the one subscriber loop interface onto the corresponding subscriber loop.

21. The method of claim 20, wherein the telephone signal outputting step comprises outputting the telephone signal as an analog POTS signal.

22. The method of claim 20, wherein the telephone signal outputting step comprises outputting the telephone signal as an ISDN signal.

23. The method of claim 21, wherein the selectively establishing step further comprises establishing the downstream broadband connection by:

outputting the broadband data, recovered from selected ATM cells on one of the multiplexed broadband data channels, to one of a plurality of ADSL modems, each ADSL modem serving a corresponding one of the subscriber loops;

outputting from the one ADSL modem a modulated signal carrying the broadband data; and

outputting from a combiner a combined signal, carrying the modulated signal and the telephone signal, to the corresponding subscriber loop.

24. The method of claim 23, wherein the selectively establishing step further comprises establishing the upstream data connection by:

recovering the data received from the corresponding subscriber loop in the one ADSL modem; and

outputting from the integrated remote terminal line card an upstream ATM cell stream carrying the recovered data received from the corresponding subscriber loop.

25. An integrated digital subscriber plug-in line card comprising:

a multiplexer/demultiplexer for logically connecting a plurality of two-way narrowband data paths serving respective subscriber loops to a bus configured for carrying digitally multiplexed narrowband data between the integrated digital subscriber plug-in line card and a central office;

telephone line interface units for connecting the two-way narrowband data paths by sending/receiving telephone signals for the respective subscriber loops;

a broadband data terminal adapter configured for receiving a digitally multiplexed broadband data stream and outputting a plurality of demultiplexed broadband data streams for the respective subscriber loops, the broadband data terminal multiplexing upstream data streams, received from the respective subscriber loops, onto the digitally multiplexed broadband data stream;

a plurality of digital subscriber loop modems for modulating the demultiplexed broadband data streams into downstream analog signals, respectively, and demodulating upstream subscriber loop control signals received from the subscriber loops into the upstream data streams, respectively; and

a plurality of subscriber loop multiplexer/demultiplexer circuits for transmitting the downstream analog signals and the telephone signals to the respective subscriber loops at first and second signal channels, respectively, and demultiplexing the upstream subscriber loop signals from the respective subscriber loops at a third signal channel.

26. The integrated digital subscriber plug-in line card of claim 25, further comprising a controller for controlling the selective output of the demultiplexed broadband data streams by the broadband data terminal adapter and the multiplexing of the upstream data streams based on supplied logical connection data.

27. The integrated digital subscriber plug-in line card of claim 26, wherein the controller dynamically controls the logical connections by the multiplexer/demultiplexer based on supplied call setup data.

28. The integrated digital subscriber plug-in line card of claim 25, wherein the broadband data terminal is an ATM adapter configured for outputting the demultiplexed broadband data streams based on reception of ATM cell streams in the digitally multiplexed broadband data stream having prescribed virtual address information.

29. The integrated digital subscriber plug-in line card of claim 28, wherein the ATM adapter outputs each demultiplexed broadband data stream as one of the ATM cell streams having a prescribed virtual address, each digital subscriber loop modem modulating the corresponding ATM cell stream into the corresponding downstream analog signal.

30. The integrated digital subscriber plug-in line card of claim 28, wherein the ATM adapter recovers the broadband data streams from the received ATM cell streams.

31. The integrated digital subscriber plug-in line card of claim 25, wherein the telephone line interface units are POTS interface circuits.

32. The integrated digital subscriber plug-in line card of claim 25, wherein the telephone line interface units are ISDN interface circuits.

33. The integrated digital subscriber plug-in line card of claim 25, further comprising a plug-in connector interface for connecting the multiplexer/demultiplexer and the broadband terminal adapter to the bus and the digitally multiplexed broadband data stream, respectively.