Two-way broadband CATV communication network protocol and monitoring technology

• US 5,768,280 A
• Filed: 10/16/1996
• Issued: 06/16/1998
• Est. Priority Date: 01/12/1995
• Status: Expired due to Term

• Current Assignee: Way, Winston I.
• Original Assignee: Way, Winston I.
• Inventors: Way, Winston I.
• Primary Examiner(s): Kizou, Hassan
• Application Number:
  US08/730,960
• Time in Patent Office: 608 Days
• Field of Search: 370/24, 370/30, 370/32, 370/69.1, 370/73, 370/85.7, 370/85.8, 370/95.1, 370/95.2, 370/319, 370/344, 370/431, 370/480, 370/485, 370/486, 370/487, 340/825.06, 340/825.07, 340/825.08, 340/825.52, 340/825.54, 348/6, 348/7, 348/10, 348/12, 348/13, 455/3.1, 455/4.1, 455/4.2, 455/5.1, 455/2
• US Class Current: 370/486
• 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: H04L 12/2801 Broadband local area networks
• 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 7/17309 Transmission or handling of upstream communications

Abstract

A medium-access protocol is disclosed for use in a communication network to provide a two-way broadband communication network. The communication network comprises a central network controller (CNC) and a plurality of user nodes, and the protocol comprises the steps of: (a) providing an RF modulator and a receiver tuner for each of the user nodes; (b) allocating a plurality of vacant CATV channel for the CNC, each channel being assigned a separate frequency band; (c) causing a first user node, which intents to communicate with a second user node, to send a request-to-communicate signal to the CNC via a first frequency band centered at first frequency, the first user node having a first RF modulator and a first receiver tuner, and the second user node having a second RF modulator and a second receiver tuner; (d) causing the CNC to send a checking signal to the second user via a second frequency band centered at second frequency to see whether the second user is busy; (e) if the second user is not busy, then causing the CNC to assign a third frequency band centered at a third carrier frequency to the first RF modulator provided for the first user node and a fourth frequency band centered at a fourth carrier frequency to the second RF modulator provided for the first user node, and tuning the first receiver tuner to the fourth carrier frequency and tuning the second receiver tuner to the third carrier frequency; and (f) causing the first user node and the second user node to communicate via the third and fourth frequency bands. With this protocol, about 600 (analog) to 10,000 (digital) pairs of users can be allowed to communicate with each other at the same time. A security checking procedure can be provided by: (a) roll-call polling each user node to check a status thereof; and (b) warning a network manager if no response is received from any of the user nodes within a predetermined period of time.

Claims

1. In a CATV network capable of delivering program video information to each of plural user nodes, a medium-access protocol for providing two-way video communication on vacant channels not already used for delivering program video information between a first user node attached to a first group of nodes and a second user node attached to a second group of nodes, wherein said first and second groups of nodes are connected to a head end comprising a central network controller (CNC), said protocol comprising the steps of:

(a) allocating a plurality of vacant CATV channels that do not carry said program video information for dynamic assignment by said CNC to communicating user nodes, each channel being assigned a separate frequency band;

(b) at said first user node, transmitting a request-to-communicate signal to said CNC via a first frequency band centered at a first frequency;

(c) transmitting from said CNC to said second user node via a second frequency band centered at a second frequency a checking signal to determine if said second user node is busy;

(d) if said second user node is not busy, assigning a third frequency band centered at a third carrier frequency to said first user node for transmitting information to said second user node and assigning a fourth frequency band centered at a fourth carrier frequency to said second user node, for transmitting information to said first user node;

(e) tuning a transmit modulator at said first user node to said third frequency, a transmit modulator at said second node to said fourth frequency, and a receive modulator at said second user node to said third frequency;

(f) transmitting a first signal modulated onto said third frequency from said first user node to said head end;

(g) at said head end, adding said first signal to each of said signals transmitted by said CNC, and each other node of said first and second groups to produce a combined signal;

(h) transmitting said combined signal to said first and second groups of nodes connected to said head end; and

(i) demodulating said first signal from said third frequency and one or more of said signals transmitted from said CNC, at said second user node.

2. A medium-access protocol according to claim 1 wherein said CATV network has a centralized star architecture or a tree-and-branch architecture connected via a single or two cables.

3. A medium-access protocol according to claim 1 which further comprising a security checking protocol, said security checking protocol comprising the step of:

roll-call polling each user node to check a status thereof; and

warning a network manager if no response is received from any of said user nodes within a predetermined period of time.

4. A medium-access protocol according to claim 1 wherein said CATV network comprises a mixture of coaxial cables and optical cables.

5. A medium-access protocol according to claim 1 wherein said CATV network comprises only coaxial cables.

6. A medium-access protocol according to claim 1 wherein each of said CATV channels has a bandwidth of 6 MHZ.

7. A medium-access protocol according to claim 1, further comprising the steps of:

tuning a receive modulator at said first user node to said fourth, frequency;

transmitting a second signal modulated onto said fourth frequency from said second user node to said head end whereby said combined signal further comprises said second signal; and

demodulating said second signal from said fourth frequency at said first user node.