Broadband communication system having a virtual circuit space switch

• US 5,905,726 A
• Filed: 05/21/1996
• Issued: 05/18/1999
• Est. Priority Date: 05/21/1996
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Gupta, Dev V.
• Primary Examiner(s): Kizou, Hassan
• Application Number:
  US08/651,825
• Time in Patent Office: 1,092 Days
• Field of Search: 370/390, 370/395, 370/398, 370/399, 370/401, 370/419, 370/421, 370/422, 370/423, 370/427, 544/3.1, 544/4.1, 544/4.2, 348/6, 348/7, 348/16, 375/298
• US Class Current: 370/390
• CPC Class Codes: H04L 12/5601 Transfer mode dependent, e.g. ATM
• CPC Class Codes: H04L 2012/5605 Fibre
• CPC Class Codes: H04L 2012/5613 Bus (including DQDB)
• CPC Class Codes: H04L 2012/5618 Bridges, gateways [GW] or interworking units [IWU]
• CPC Class Codes: H04L 2012/5681 Buffer or queue management
• CPC Class Codes: H04L 49/106 using space switching, e.g. crossbar or matrix
• CPC Class Codes: H04L 49/1576 Crossbar or matrix
• CPC Class Codes: H04L 49/203 ATM switching fabrics with multicast or broadcast capabilities
• CPC Class Codes: H04L 49/309 Header conversion, routing tables or routing tags
• CPC Class Codes: H04N 7/147 Communication arrangements, e.g. identifying the communication as a video-communication, intermediate storage of the signals selecting H04Q
• CPC Class Codes: H04N 7/15 Conference systems
• CPC Class Codes: H04N 7/17318 Direct or substantially direct transmission and handling of requests

Abstract

A communication system is described which enables efficient delivery of asymmetrical bandwidth signals over a communication network. The system includes a virtual circuit switch having a space switch coupled thereto for distributing downstream signals from a backbone network to subscribers in a cost effective manner.

Claims

1. A communication system for transmitting video signals to subscribers comprising:

a source of video signals; and

a switch having;

a digital communication bus;

a first interface unit coupled to the source for coupling the video signals onto the digital communication bus;

an analog communication bus;

a transmitter coupled to the digital communication bus for amplitude modulating a carrier signal with the video signals and transmitting the AM signals onto the analog communication bus; and

a plurality of second interface units coupled to the analog communication bus, each second interface unit operable to transmit a subset of the AM signals requested by associated subscribers.

2. The system of claim 1 further comprising a communication link coupled between the source and the switch.

3. The system of claim 1 wherein the source is an access gateway coupled to at least one backbone network.

4. The system of claim 1 further comprising a plurality of residential gateway devices, each gateway device coupled to a one of the second interface units over a copper communication link and operable to receive at least one of the signals in the associated subset of AM signals.

5. The system of claim 1 wherein the video signals are provided as Asynchronous Transfer Mode cells.

6. The system of claim 1 wherein the transmitter converts video signals into a Quadrature Amplitude Modulation signal.

7. The system of claim 1 wherein each second interface unit further comprises a space switch coupled to the analog bus for selecting from among the AM signals the requested subset of AM signals.

8. A data communication switch for selecting video signals for transmission to subscribers, comprising:

a digital communication bus;

a first interface unit for receiving the video signals and coupling the video signals to the digital communication bus;

an analog communication bus;

a transmitter coupled to the digital communication bus for amplitude modulating a carrier signal with the video signals and transmitting the AM signals onto the analog communication bus; and

a plurality of second interface units coupled to the analog communication bus, each second interface unit operable to transmit a subset of AM signals requested by associated subscribers.

9. The switch of claim 8 wherein the video signals are provided by an access gateway coupled to at least one backbone network.

10. The switch of claim 9 wherein the video signals are provided as Asynchronous Transfer Mode cells.

11. The switch of claim 8 wherein the transmitter converts a set of three video data signals into a Quadrature Amplitude Modulation signal.

12. The switch of claim 8 wherein each second interface unit further comprises a space switch coupled to the analog bus for selecting from among the AM signals the requested subset of AM signals.

13. A method of communication comprising:

providing a source of video signals;

coupling the video signals onto a digital communication bus;

amplitude modulating a carrier signal with the video signals from the digital communication bus and coupling the AM signals onto an analog communication bus; and

transmitting a subset of the AM signals to a subscriber responsive to a subscriber request.

14. The method of claim 13 further comprising the step of coupling the subset of AM signals over a copper communication link to the subscriber.

15. The method of claim 13 wherein the video signals are provided as Asynchronous Transfer Mode cells.

16. The method of claim 13 wherein the amplitude modulation is Quadrature Amplitude Modulation.

17. In an ATM network, a method of communication comprising the steps of:

receiving a digital signal comprising message cells on a first input port of a virtual circuit switch, the message cells having a virtual circuit identifier associated with a particular first output port;

routing the message cells to the associated first output port;

coupling message cells on the first output port to a second input port of a space switch; and

distributing the message cells to at least one second output port wherein the step of coupling includes converting the digital signal to an amplitude modulated signal.

18. The method of claim 17 wherein the amplitude modulated signal is a Quadrature Amplitude Modulated signal.