Broadband communications system

• US 5,499,241 A
• Filed: 09/17/1993
• Issued: 03/12/1996
• Est. Priority Date: 09/17/1993
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Scientific-Atlanta Incorporated (Cisco Systems, Inc.)
• Inventors: Fellows, David M., Ritchie, John A. Jr., Thompson, Leo J., Dubberly, Gregory T.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Patel, Ajit
• Application Number:
  US08/123,363
• Time in Patent Office: 907 Days
• Field of Search: 370/69.1, 370/73, 370/71, 455/4-6, 455/3.1, 455/74, 348/12, 348/13, 348/11, 348/8, 348/6, 348/14, 348/15, 348/16, 379/64, 375/7, 375/8
• US Class Current: 370/486
• CPC Class Codes: H04H 20/81 combined with telephone network over which the broadcast is continuously available
• CPC Class Codes: H04H 60/96 CATV systems for accessing the Internet H04H60/86
• CPC Class Codes: H04J 1/12 Arrangements for reducing cross-talk between channels in line transmission systems H04B3/32; in cables or lines H04B3/26 - H04B3/30
• CPC Class Codes: H04J 2203/0041 Star, e.g. cross-connect, concentrator, subscriber group equipment, remote electronics
• CPC Class Codes: H04J 2203/0089 Multiplexing, e.g. coding, scrambling, SONET
• CPC Class Codes: H04J 3/1623 Plesiochronous digital hierarchy [PDH]
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: H04M 7/006 Networks other than PSTN/ISDN providing telephone service, e.g. Voice over Internet Protocol (VoIP) , including next generation networks with a packet-switched transport layer H04L65/00 takes precedence; aspects not specific to the type of network H04M3/00; special services in those networks H04M3/42
• CPC Class Codes: H04N 2007/1739 the upstream communication being transmitted via a separate link, e.g. telephone line
• CPC Class Codes: H04N 7/10 Adaptations for transmission by electrical cable H04N7/12 takes precedence
• CPC Class Codes: H04N 7/17309 Transmission or handling of upstream communications
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections
• CPC Class Codes: H04Q 2213/13332 Broadband, CATV, dynamic bandwidth allocation

Abstract

A broadband communications system for coupling telephony or other digital networks to a CTV network. The system includes transmitting a multiplex of telephony signals in 3 MHz channels in the forward band of the CTV network. Each 3 MHz channel is QPR modulated on a carrier and contains multiple subscriber telephony signals. The forward telephony channels are demodulated and demultiplexed by a plurality of subscriber terminals into the individual telephony signals directed to an addressed subscriber. The individually addressed telephony signal is then applied to a line card which connects the subscriber telephone equipment to the system. Audio and control signals returning from the subscriber are digitized into standard telephony signals and modulated on a carrier in 50 kHz reserved telephony channels onto the reverse band of the CTV network. The multiplicity of reverse band telephony channels are demodulated and multiplexed into a standard telephony signal which can be directly interfaced to the telephony network. In the illustrated embodiment, the CTV network has a fiber to the serving area architecture that can be used to increase the number of reverse band channels which are available to the broadband communications system. Several configurations for the system are described where the input and output interface can both be coupled at the headend or both coupled at a fiber node, or either one coupled at the headend while the other is coupled at a fiber node.

Claims

1. An apparatus for the communications of incoming telephony signals from a telephony network to a plurality of subscribers of a subscription system and for the communication of outgoing telephony signals from the plurality of subscribers to the telephony network, said subscription system including a subscription network having a forward band of frequencies and a reverse band of signaling frequencies, said apparatus comprising:

a first modulator for modulating the incoming telephony signals from the telephony network on a carrier in the forward band of said subscription network;

a subscriber terminal demodulator for demodulating the incoming telephony signals from the selected one of the plurality of subscribers;

a second modulator for modulating the outgoing telephony signals from the selected one of the plurality of subscribers on a carrier in the reverse band of the subscription network;

an outgoing telephony signal demodulator for demodulating the outgoing telephony signals from the reverse band of the subscription network; and

a first coupler for coupling the incoming and outgoing telephony signals with the telephony network;

wherein said incoming and outgoing telephony signals are selected from the group including SONET, OC-1, DS3, DS2, DS1 and E-1;

wherein said first coupler comprises a first demultiplexor for demultiplexing and decoding each of said incoming telephony signals into groups of telephony signals;

wherein said first modulator modulates each group onto a separate group carrier which is frequency division multiplexed in the forward band of the subscription network;

wherein said subscriber terminal demodulator includes;

a tuner for tuning at least one group carrier and demodulating said groups of telephony signals;

a second demultiplexor, coupled to said tuner, for demultiplexing said groups of telephony signals into individual subscriber telephone signals;

a selecting element, coupled to said second demultiplexor, for selecting the individual subscriber telephony signal addressed to the subscriber, and

a second coupler for coupling said individual subscriber telephony signal to a subscriber line and which is coupled to the telephone equipment of the subscriber.

2. An apparatus for the communication of incoming telephony signals from a telephony network to a plurality of subscribers of a subscription system and for the communication of outgoing telephony signals from the plurality of subscribers to the telephony network, said subscription system including a subscription network having a forward band of frequencies and a reverse band of signaling frequencies, said apparatus comprising:

first means for modulating the incoming telephony signals from the telephony network on a carrier in the forward band of said subscription network;

subscriber terminal means for demodulating the incoming telephony signals from the subscription network and coupling them to a particular one of the plurality of subscribers;

second means for modulating the outgoing telephony signals from the particular one of the plurality of subscribers on a subscriber telephony carrier in the reverse band of the subscription network;

means for demodulating the outgoing telephony signals from the reverse band of the subscription network; and

means for coupling the incoming and outgoing telephony signals with the telephony network;

wherein said subscriber terminal means further includes means for coupling the subscriber telephone equipment to said subscriber terminal means;

wherein said coupling means includes means for digitizing the telephony signals from the subscriber;

wherein said digitizing means includes means for digitizing the telephony from the subscriber and combining them with digitized control and addressing information;

wherein said digitized telephony signals from the subscriber are in DS0 format;

wherein said second means for modulating modulates said subscriber telephony carrier with a QPSK modulation having a bandwidth of approximately 50 kHz;

wherein said means for demodulating the telephony signals from the reverse band includes;

a plurality of demodulators, each for tuning and demodulating a subscriber telephony carrier of the reverse band of the subscriber network and generating a plurality of demodulated subscriber telephony signals; and

means for multiplexing the subscriber telephony signals of the subscriber network into a combined telephony signal, wherein said combined telephony signal is in one of OC-1, DS1, DS2, DS3, and E-1 format.

3. An apparatus for the communication of incoming telephony signals from a telephony network to a plurality of subscribers of a subscription system and for the communication of outgoing telephony signals from the plurality of subscribers to the telephony network, said subscription system including a subscription network having a forward band of frequencies and a reverse band of signaling frequencies, said apparatus comprising:

a first modulator for modulating the incoming telephony signals from the telephony network on a carrier in the forward band of said subscription network, said incoming telephony signals from the telephony network comprising a digital multiplexed input signal including a plurality of input data channels, the position of a particular input data channel in the multiplexed input signal indicating the destination of the data in that channel to the particular one of the plurality of subscribers;

a subscriber terminal demodulater for demodulating the incoming telephony signals from the subscription network and coupling them to a particular one of the plurality of subscribers;

a second modulator, associated with said subscriber terminal demodulater, for modulating the outgoing telephony signals from the particular one of the plurality of subscribers on a carrier in the reverse band of the subscription network, said outgoing telephony signals to the telephony network comprising a digital multiplexed output signal including a plurality of output data channels, the position of a particular output data channel in the multiplexed output signal indicating the origin of the data in that channel from the particular one of the plurality of subscribers;

an outgoing telephony signal demodulator for demodulating the outgoing telephony signals from the reverse band of the subscription network;

a first coupler for coupling the incoming telephony signals from the telephony network to said first modulator, said first coupler coupling the particular input data channel to a predetermined carrier in the forward band of the subscription network; and

a second coupler for coupling the outgoing telephony signals from said outgoing telephony signal demodulator to the telephony network, said second coupler coupling the outgoing telephony signals from the particular one of the plurality of subscribers in the reverse band of the subscription network to the particular output data channel.

4. The apparatus as set forth in claim 3 wherein said incoming and outgoing telephony signals are selected from the group including SONET, OC-1, DS3, DS2, DS1 and E-1.

5. The apparatus as set forth in claim 4 wherein said first coupler comprises:

a demultiplexor for demultiplexing and decoding each of said incoming telephony signals into groups of telephony signals;

said first modulator modulating each group onto a separate carrier which is frequency division multiplexed in the forward band of the subscription network.

6. The apparatus as set forth in claim 5 wherein said first modulator modulates each group carrier with a QPR modulation.

7. The apparatus as set forth in claim 6 wherein said subscription network carries a plurality of frequency division multiplexed subscription channels with a guard band on each side of a subscription channel;

and

wherein said first modulator frequency division multiplexes said forward telephony channels with said subscription channels.

8. The apparatus as set forth in claim 7 wherein said first modulator frequency division multiplexes at least one of said forward band telephony channels in the guard bands between two adjacent subscription channels.

9. The apparatus as set forth in claim 7 wherein said first modulator frequency division multiplexes said forward telephony channels in portions of the forward band unused by the subscription channels.

10. The apparatus as set forth in claim 7 wherein said first modulator frequency division multiplexes at least two of the forward telephony channels into adjacent locations in the forward band.

11. The apparatus as set forth in claim 5 wherein said subscriber terminal demodulator includes:

a tuner for tuning at least one group carrier and demodulating said groups of telephony signals;

a second demultiplexor, coupled to said tuner, for demultiplexing said groups of telephony signals into individual subscriber telephone signals; and

a selector, coupled to said second demultiplexor, for selecting the individual subscriber telephony signal addressed to the subscriber.

12. The apparatus as set forth in claim 11 wherein said subscriber terminal demodulator further includes:

a third coupler for coupling said selected individual subscriber telephony signal to a subscriber line which is coupled to the telephone equipment of the subscriber.

13. The apparatus as set forth in claim 3 wherein said first modulator modulates the incoming telephony signals from the telephony network by a QPR modulation;

and

wherein said second modulator modulates the outgoing telephony signals from the particular one of the plurality of subscribers by a QPSK modulation.

14. The apparatus as set forth in claim 3 wherein said subscriber terminal demodulator further includes a fourth coupler for coupling the telephone equipment to said subscriber terminal demodulator.

15. The apparatus as set forth in claim 14 wherein said fourth coupler includes a digitizer, coupled to the subscriber telephone equipment, for digitizing the telephony signal from the subscriber.

16. The apparatus as set forth in claim 15 further comprising a combiner, coupled to the digitizer, for combining the digitized telephony signal from the subscriber with digitized control and addressing information.

17. The apparatus as set forth in claim 16 wherein said digitized telephony signals from the subscriber are in DS0 format.

18. The apparatus as set forth in claim 3 wherein said second modulator modulates a separate carrier from the subscriber terminal which is frequency division multiplexed with other subscriber telephony carriers in the reverse band of the subscription network.

19. The apparatus as set forth in claim 18 wherein said second modulator modulates each subscriber telephony carrier with a QPSK modulation.

20. The apparatus as set forth in claim 19 wherein said second demodulator includes a plurality of demodulators, each for tuning and demodulating a subscriber telephony carrier of the reverse band of the subscription network into a combined telephony signal.

21. The apparatus as set forth in claim 20 wherein said second demodulator further includes a second demultiplexor for demultiplexing the subscriber telephony signals of the subscription network into a combined telephony signal.

22. The apparatus as set forth in claim 21 wherein said combined digital telephony signal is in one of OC-1, DS1, DS2, DS3 and E-1 format.

27. The apparatus as set forth in claim 7 wherein said subscriber terminal demodulator further includes:

a third coupler for coupling said selected individual subscriber telephony signal to a subscriber line which is coupled to the telephone equipment of the subscriber.

23. An apparatus for the communication of incoming telephony signals from a telephony network to a plurality of subscribers of a subscription system and for the communication of outgoing telephony signals from the plurality of subscribers to the telephony network, said subscription system including a subscription network having a forward band of frequencies and a reverse band of signaling frequencies, said apparatus comprising:

a first modulator for modulating the incoming telephony signals from the telephony network on a carrier in the forward band of said subscription network;

a subscriber terminal demodulator for demodulating the incoming telephony signals from the subscription network and coupling them to a particular one of the plurality of subscribers;

a second modulator, associated with said subscriber terminal element, for modulating the outgoing telephony signals from the particular one of the plurality of subscribers on a carrier in the reverse band of the subscription network;

an outgoing telephony signal demodulator for demodulating the outgoing telephony signals from the reverse band of the subscription network;

a first coupler for coupling the incoming telephony signals from the telephony network to said first modulator; and

a second coupler for coupling the outgoing telephony signals from said outgoing telephony signal demodulator to the telephony network;

said incoming and outgoing telephony signals being selected from the group including SONET, OC-1, DS3, DS2 and E-1;

said first coupler comprising a demultiplexor for demultiplexing and decoding said incoming telephony signals into groups of telephony signals;

said first modulator modulating each group onto a separate carrier which is frequency division multiplexed in the forward band of the subscription network as forward telephony channels;

said first modulator modulating each group carrier with QPR modulation having a bandwidth of approximately 3 MHz;

said subscription network carrying a plurality of frequency division multiplexed 4.5 MHz subscription channels with a 1.5 MHz guard band on each side of a subscription channel;

said first modulator frequency division multiplexing said forward telephony channels with the subscription channels; and

said first modulator frequency division multiplexing at least one of said forward band telephony channels in the guard bands between two adjacent subscription channels.

24. An apparatus for the communication of incoming telephony signals from a telephony network to a plurality of subscribers of a subscription system and for the communication of outgoing telephony signals from the plurality of subscribers to the telephony network, said subscription system including a subscription network having a forward band of frequencies and a reverse band of signaling frequencies, said apparatus comprising:

a first modulator for modulating the incoming telephony signals from the telephony network on a carrier in the forward band of said subscription network;

a subscriber terminal demodulator for demodulating the incoming telephony signals from the subscription network and coupling them to a particular one of the plurality of subscribers;

a second modulator, associated with said subscriber terminal element, for modulating the outgoing telephony signals from the particular one of the plurality of subscribers on a carrier in the reverse band of the subscription network;

an outgoing telephony signal demodulator for demodulating the outgoing telephony signals from the reverse band of the subscription network;

a first coupler for coupling the incoming telephony signals from the telephony network to said first modulator; and

a second coupler for coupling the outgoing telephony signals from said outgoing telephony signal demodulator to the telephony network;

said incoming and outgoing telephony signals being selected from the group including SONET, OC-1, DS3, DS2 and E-1;

said first coupler comprising a demultiplexor for demultiplexing and decoding said incoming telephony signals into groups of telephony signals;

said first modulator modulating each group onto a separate carrier which is frequency division multiplexed in the forward band of the subscription network as forward telephony channels;

said first modulator modulating each group carrier with QPR modulation having a bandwidth of approximately 3 MHz;

said subscription network carrying a plurality of frequency division multiplexed 4.5 MHz subscription channels with a 1.5 MHz guard band on each side of a subscription channel;

said first modulator frequency division multiplexing said forward telephony channels with the subscription channels; and

said first modulator frequency division multiplexing said forward telephony channels in portions of the forward band unused by the subscription channels.

25. An apparatus for the communication of incoming telephony signals from a telephony network to a plurality of subscribers of a subscription system and for the communication of outgoing telephony signals from the plurality of subscribers to the telephony network, said subscription system including a subscription network having a forward band of frequencies and a reverse band of signaling frequencies, said apparatus comprising:

a first modulator for modulating the incoming telephony signals from the telephony network on a carrier in the forward band of said subscription network;

a subscriber terminal demodulator for demodulating the incoming telephony signals from the subscription network and coupling them to a particular one of the plurality of subscribers;

a second modulator, associated with said subscriber terminal element, for modulating the outgoing telephony signals from the particular one of the plurality of subscribers on a carrier in the reverse band of the subscription network;

an outgoing telephony signal demodulator for demodulating the outgoing telephony signals from the reverse band of the subscription network;

a first coupler for coupling the incoming telephony signals from the telephony network to said first modulator; and

a second coupler for coupling the outgoing telephony signals from said outgoing telephony signal demodulator to the telephony network;

said incoming and outgoing telephony signals being selected from the group including SONET, OC-1, DS3, DS2 and E-1;

said first coupler comprising a demultiplexor for demultiplexing and decoding said incoming telephony signals into groups of telephony signals;

said first modulator modulating each group onto a separate carrier which is frequency division multiplexed in the forward band of the subscription network as forward telephony channels;

said first modulator modulating each group carrier with QPR modulation having a bandwidth of approximately 3 MHz;

said subscription network carrying a plurality of frequency division multiplexed 4.5 MHz subscription channels with a 1.5 MHz guard band on each side of a subscription channel;

said first modulator frequency division multiplexing said forward telephony channels with the subscription channels; and

said first modulator frequency division multiplexing at least two of the forward band telephony channels into adjacent locations in the forward band.

26. An apparatus for the communication of incoming telephony signals from a telephony network to a plurality of subscribers of a subscription system and for the communication of outgoing telephony signals from the plurality of subscribers to the telephony network, said subscription system including a subscription network having a forward band of frequencies and a reverse band of signaling frequencies, said apparatus comprising:

a first modulator for modulating the incoming telephony signals from the telephony network on a carrier in the forward band of said subscription network;

a subscriber terminal demodulator for demodulating the incoming telephony signals from the subscription network and coupling them to a particular one of the plurality of subscribers;

a second modulator, associated with said subscriber terminal element, for modulating the outgoing telephony signals from the particular one of the plurality of subscribers on a carrier in the reverse band of the subscription network;

an outgoing telephony signal demodulator for demodulating the outgoing telephony signals from the reverse band of the subscription network;

a first coupler for coupling the incoming telephony signals from the telephony network to said first modulator; and

a second coupler for coupling the outgoing telephony signals from said outgoing telephony signal demodulator to the telephony network;

said incoming and outgoing telephony signals being selected from the group including SONET, OC-1, DS3, DS2 and E-1;

said first coupler comprising a first demultiplexor for demultiplexing and decoding said incoming telephony signals into groups of telephony signals;

said first modulator modulating each group onto a separate carrier which is frequency division multiplexed in the forward band of the subscription network as forward telephony channels;

said subscriber terminal demodulator including;

a tuner for tuning at least one group carrier and demodulating said groups of telephony signals;

a second demultiplexor, coupled to said tuner, for demultiplexing said groups of telephony signals into individual subscriber telephone signals; and

a selector, coupled to said second demultiplexor, for selecting the individual subscriber telephony signal addressed to the subscriber.

28. An apparatus for the communication of incoming telephony signals from a telephony network to a plurality of subscribers of a subscription system and for the communication of outgoing telephony signals from the plurality of subscribers to the telephony network, said subscription system including a subscription network having a forward band of frequencies and a reverse band of signaling frequencies, said subscription network carrying a plurality of frequency division multiplexed subscription channels, said apparatus comprising:

a first modulator for modulating the incoming telephony signals from the telephony network on a carrier in the forward band of said subscription network, said first modulator modulating a group of incoming telephony signals with QPR modulation onto a separate carrier which is frequency division multiplexed in the forward band of the subscription network with said subscription channels;

a subscriber terminal demodulator for demodulating the incoming telephony signals from the subscription network and coupling them to a particular one of the plurality of subscribers;

a second modulator, associated with said subscriber terminal demodulator, for modulating the outgoing telephony signals from the particular one of the plurality of subscribers on a carrier in the reverse band of the subscription network;

an outgoing telephony signal demodulator for demodulating the outgoing telephony signals from the reverse band of the subscription network;

a first coupler for coupling the incoming telephony signals from the telephony network to said first modulator; and

a second coupler for coupling the outgoing telephony signals from said outgoing telephony signal demodulator to the telephony network.

29. The apparatus as set forth in claim 28 wherein said incoming and outgoing telephony signals are selected from the group including SONET, OC-1, DS3, DS2 and E-1.

30. The apparatus as set forth in claim 29 wherein said first coupling element comprises a demultiplexor for demultiplexing and decoding each of said incoming telephony signals into groups of telephony signals

31. The apparatus as set forth in claim 30 wherein said first modulator modulates each group carrier with a QPR modulation.

32. The apparatus as set forth in claim 31 wherein said first modulator frequency division multiplexes at least one of said forward band telephony channels in the guard bands between two adjacent subscription channels.