Growable architecture for high-speed two-way data services over CATV networks

• US 6,014,545 A
• Filed: 03/27/1997
• Issued: 01/11/2000
• Est. Priority Date: 03/27/1997
• Status: Expired due to Term

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Ma, Gin-Kou, Wu, Chiung-Shien
• Primary Examiner(s): Kostak, Victor R.
• Application Number:
  US08/827,175
• Time in Patent Office: 1,020 Days
• Field of Search: 455/3.1, 455/3.3, 348/6, 348/12, 348/13, 395/200.47, 370/485-490
• US Class Current: 725/118
• CPC Class Codes: H04H 60/96 CATV systems for accessing the Internet H04H60/86
• CPC Class Codes: H04L 12/46 Interconnection of networks
• CPC Class Codes: H04N 21/6118 involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 21/6168 involving cable transmission, e.g. using a cable modem
• 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

Abstract

A cable network is provided with at least one bridge that is connected to a first cable segment of the cable network. The bridge receives from a shared communication medium a first carrier signal, having a first carrier frequency that is allocated for intra cable segment packet communication, containing packets modulated thereon. The bridge demodulates selected packets originating in the first cable segment from the first carrier signal. The bridge modulates each of the demodulated packets, that are destined outside of the first cable segment, onto a second carrier signal having a second carrier frequency. The bridge then transmits the second carrier signal on an upstream link of the common shared medium.

Claims

1. A method for communicating in a cable network comprising the steps of:

at a bridge that is connected to a first cable segment;

(a) receiving from a shared communication medium a first carrier signal, having a first carrier frequency that is allocated for intra cable segment packet communication, containing packets modulated thereon,

(b) demodulating selected packets originating in said first cable segment from said first carrier signal,

(c) modulating each of said demodulated packets, that are destined outside of said first cable segment, onto a second carrier signal having a second carrier frequency that is allocated for upstream directed inter cable segment communication,

(d) transmitting said second carrier signal on an upstream link of said common shared medium,

(e) receiving at said bridge from a downstream link of said shared communication medium, to which at least a second cable segment is connected, a third carrier signal, having said second carrier frequency,

(f) demodulating packets from said third carrier signal, and

(g) modulating each of said packets that were demodulated from said third carrier signal onto said second carrier signal.

2. The method of claim 1 further comprising the steps of:

(h) receiving at said bridge, from said upstream link, a fourth carrier signal, having a third carrier frequency that is allocated for downstream inter cable segment communication,

(i) demodulating selected packets from said fourth carrier signal, and

(j) when said first signal is idle, modulating at least one of said packets demodulated from said fourth carrier signal onto a fifth carrier signal, having said first carrier frequency, and transmitting said fifth carrier signal from said bridge in said first cable segment.

3. The method of claim 2 further comprising the steps of:

at a head end;

(k) receiving said second carrier signal from said shared medium,

(l) demodulating each packet from said second carrier signal,

(m) modulating each of said demodulated packets, that is destined to a cable segment connected downstream of said cable head end, onto said fourth carrier signal, and

(n) transmitting said fourth carrier signal from said cable head end on said shared medium.

4. The method of claim 1 further comprising the steps of:

(h) enqueuing each of said packets demodulated from said first carrier signal into a first queue,

(i) enqueuing each of said packets demodulated from said second carrier signal into a second queue, and

(j) in performing said steps (c) and (g), selectively dequeuing packets from said first or second queues for modulation onto said second carrier signal.

5. The method of claim 4 wherein said step (j) further comprises the steps of:

(k) determining a service ratio of said first and second queues according to which said first and second queues are selected for dequeuing packets, based on the number of additional bridges connected to said downstream link of said shared medium.

6. The method of claim 5 wherein an equivalent service rate of said first queue equals (n-i+1)^-1 where i-1 total cable segments are connected to said shared medium upstream of said bridge, where n-i total cable segments are connected to said shared medium downstream of said bridge, and where n total cable segments are connected to said shared medium.

7. The method of claim 4 further comprising the steps of:

(k) selectively reducing a rate of packet receipt at said bridge by said bridge causing a collision on at least one of said downstream link and said cable segment.

8. The method of claim 1 further comprising the steps of, at each of plural terminal equipments in said first cable segment containing a to-be-transmitted packet:

(e) sensing that no carrier signal, having said first carrier frequency, is present on said shared medium,

(f) modulating said to-be-transmitted packet onto a certain carrier signal having said first carrier frequency, and

(g) transmitting said certain carrier signal on said shared medium.

9. The method of claim 8 further comprising the steps of, at each of said terminal equipments:

(h) during said step (g), determining that a collision has occurred if said terminal equipment detects another transmission of another carrier signal having said first carrier frequency, and

(i) in response to said collision, determining that said to-be-transmitted packet was not successfully transmitted, waiting for a period of time and re-performing said steps (e)-(g).

10. The method of claim 1 further comprising the steps of, at said bridge:

(e) performing steps (c) and (d) only in response to sensing that no carrier signal having said second carrier frequency is present on said upstream link.

11. The method of claim 10 further comprising the steps of, at said bridge:

(f) during said step (d), determining that a collision has occurred if said bridge detects another carrier signal having said second carrier frequency on said upstream link, and

(i) in response to said collision, determining that said packet transmitted in steps (d) and (e) was not successfully transmitted, waiting for a period of time and re-performing said steps (c)-(e).

12. A method for communicating in a cable network comprising the steps of:

(a) receiving a first carrier signal, having a first carrier frequency allocated for upstream directed intra cable segment communication from a shared medium,

(b) demodulating from said first carrier signal, a packet that originated in a first cable segment connected to said shared medium and is destined to a second cable segment connected to said shared medium,

(c) modulating said demodulated packet onto a second carrier signal, having a second carrier frequency that is allocated for downstream directed inter cable segment communication,

(d) transmitting said second carrier signal on said shared medium,

(e) receiving at said bridge from a downstream link of said shared communication medium, to which at least a second cable segment is connected, a third carrier signal, having said second carrier frequency,

(f) demodulating packets from said third carrier signal, and

(g) modulating each of said packets that were demodulated from said third carrier signal onto said second carrier signal.

13. A method for communicating on a cable network comprising:

(a) organizing each terminal equipment connected to a head end via a shared medium into plural cable segments,

(b) allocating a first carrier frequency for only intra cable segment communication, a second carrier frequency for only upstream directed inter cable segment communication and a third carrier frequency for only downstream directed communication,

(c) transmitting and receiving packets at each terminal equipment that are modulated only on a carrier signal having said first carrier frequency, and

(d) at each bridge connected to one of said cable segments, transmitting packets that are destined outside of said connected cable segment, by modulating said packets on a carrier signal of only said second carrier frequency, and receiving packets that are destined to said connected cable segment, but originating outside of said connected cable segment, that are modulated on a carrier signal of only said first carrier frequency.

14. A bridge in a cable network comprising:

a first connection to a first cable segment, for receiving at least a first carrier signal, having a first carrier frequency that is allocated for intra cable segment packet communication, containing packets modulated thereon,

a first demodulator for demodulating selected packets originating in said first cable segment from said first carrier signal,

a first modulator for modulating only those of said selected packets, that are destined outside of said first cable segment, onto a second carrier signal having a second carrier frequency allocated for upstream inter cable segment packet communication, and

a second connection to an upstream shared communication medium link of said cable network for transmitting said second carrier signal

wherein said input also receives, from a downstream shared communication medium link, to which at least a second cable segment is connected, a third carrier signal, having said second carrier frequency,

said bridge further comprising a second demodulator for demodulating packets from said third carrier signal, and

wherein said first modulator modulates each of said packets that were demodulated from said third carrier signal onto said second carrier signal.

15. The bridge of claim 14:

wherein said second connection receives a fourth carrier signal, having a third carrier frequency that is allocated for downstream inter cable segment communication,

said bridge further comprising a third demodulator for demodulating packets destined to said first cable segment from said fourth carrier signal, and

a second modulator for, when said first carrier signal is idle, modulating said packets that were demodulated from said fourth carrier signal onto a fifth carrier signal, having said first carrier frequency, and

wherein said first connection transmits said fifth carrier signal to said first cable segment.

16. The bridge of claim 14 further comprising:

a buffer with a first queue for enqueuing selected ones of said packets that were demodulated by said first demodulator and a second queue for enqueuing each of said packets that were demodulated by said second demodulator, said buffer selectively outputting packets from said first queue or said second queue to said first modulator.

17. The bridge of claim 16 further comprising:

a first filter connected between said buffer and said first demodulator for selecting only those packets that were demodulated by said first demodulator and are also destined outside of said first cable segment.

18. A cable network comprising:

a shared medium,

a plurality of terminal equipments connected to said shared medium and organized into plural cable segments,

a first carrier frequency, in a frequency band of said shared medium, allocated for only intra cable segment communication,

a second carrier frequency, in said frequency band of said shared medium, allocated for only upstream directed inter cable segment communication,

a third carrier frequency, in said frequency band of said shared medium, allocated for only downstream directed inter cable segment communication, and

at least one bridge connected to at least one of said cable segments,

wherein each of said terminal equipments transmits and receives packets that are modulated only on carrier signals having said first carrier frequency, and

wherein said at least one bridge receives packets from terminal equipments in said connected at least one cable segment that are modulated only on said carrier signals having said first frequency, transmits those of said received packets, that are destined outside of said connected at least one cable segment, by modulating said received packets on a second carrier signal having said second carrier frequency, receives second packets that are destined to said at least one connected cable segment, by demodulating said second packets from a third carrier signal having said third carrier frequency, and transmits said second packets by modulating said second packets on a fourth carrier signal having said first carrier frequency.