System and method of bidirectional digital video communication over a cable

• US 6,237,146 B1
• Filed: 03/19/1997
• Issued: 05/22/2001
• Est. Priority Date: 03/19/1997
• Status: Expired due to Fees

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Richards, Claudia K., Buchanan, William M.
• Primary Examiner(s): Miller, John W.
• Application Number:
  US08/820,734
• Time in Patent Office: 1,525 Days
• Field of Search: 709/217-219, 348/6, 348/7, 348/12, 348/13, 348/10, 455/3.1, 455/4.1, 455/4.2, 455/5.1, 455/6.1, 455/6.2, 370/445, 370/446, 370/447, 370/448, 725/114, 725/131, 725/132, 725/91, 725/100, 725/103, 725/86
• US Class Current: 725/100
• CPC Class Codes: H04N 21/2396 characterized by admission policies admission control, resource allocation in open networks H04L12/5692; arrangements for network security using user profiles for access control H04L63/102; access security in wireless networks H04W12/08
• CPC Class Codes: H04N 21/643 Communication protocols network streaming protocols, e.g. real-time transport protocol [RTP] or real-time control protocol [RTCP], H04L65/65
• CPC Class Codes: H04N 7/17309 Transmission or handling of upstream communications

Abstract

In accordance with the present invention, a cable system allows bidirectional digital communication between a plurality of subscriber Digital Video Home Terminals each located at a different subscriber location and a cable headend via a RF Trunk. The cable headend has a processor for calculating and storing a randomized back-off array for each of the plurality of subscriber Digital Video Home Terminals. Each subscriber Digital Video Home Terminal receives the randomized back-off array for controlling through an algorithm when a Digital Video Home Terminal attempts to send a message to a cable headend. If a collision between the two messages is imminent, the last Digital Video Home Terminal to send the message backs-off and then reattempts to send the message a plurality of times after a random back-off interval of time has passed after each reattempt until no collision would occur with another message generated from a different Digital Video Home Terminal.

Claims

1. A method of bidirectional digital communication over cable comprising the step of:

receiving, in response to an initialization signal, within each of a plurality of different subscriber digital video home terminals located at different subscriber locations and in communication with a cable headend a randomized back-off array for controlling when a subscriber digital video home terminal attempts to send a message to the cable headend and then reattempts to send the message a plurality of times after a random back-off interval of time has passed after each reattempt until no collision would occur with another message generated from another subscriber home terminal, the randomized back-off array being generated at the cable headend with a two-stage back-off retry algorithm.

2. A method according to claim 1 including the step of generating the randomized back-off array at the cable headend and initializing the digital video home terminal with the randomized back-off array so that the digital video home terminal can establish communication with the cable headend.

3. A method according to claim 1 including the step of storing the back-off array within a Random Access Memory of the digital video home terminal.

4. A method according to claim 1 including the step of reattempting message transmissions after a respective time-out period that is a first randomized interval of time and then reattempting message transmissions after a respective time-out period that is a second randomized interval of time.

5. A method according to claim 1 wherein the first randomized interval of time is calculated from a uniformly distributed retry algorithm and the second randomized interval of time is calculated from an exponential retry algorithm.

6. A method according to claim 1 including the step of reattempting to send a message if an acknowledgement of message receipt is not received from the cable headend.

7. A method of bidirectional digital communication along a cable comprising the steps of:

initializing communication with a cable headend by booting a subscriber digital video home terminal located at a subscriber premises and receiving from the cable headend a randomized back-off array that is used to calculate random back-off intervals of time, the randomized back-off array being generated at the cable headend with a two-stage back-off retry algorithm,

attempting to send a message to the cable headend and backing-off from sending the message if a collision with another message generated from a different subscriber digital video home terminal would occur, and

reattempting to send the message a plurality of times after a random back-off interval of time has passed until no collision would occur with another message generated from a different home terminal.

8. A method according to claim 7 including the step of generating the back-off array at the cable headend.

9. A method according to claim 7 including the step of storing the back-off array within a Random Access Memory of the digital video home terminal.

10. A method according to claim 7 including the step of reattempting to send a message if an acknowledgement is not received from the cable headend.

11. A method according to claim 7 including the step of reattempting message transmissions after a respective time-out period that is a first randomized interval of time and then reattempting message transmissions after a respective time-out period that is a second randomized interval of time.

12. A method according to claim 7 wherein the first randomized interval of time is calculated from a uniformly distributed retry algorithm and the second randomized interval of time is calculated from an exponential retry algorithm.

13. A cable system that permits bidirectional digital communication along a cable with minimum message collisions comprising:

a plurality of subscriber digital video home terminals each located at a different subscriber location,

a cable headend having a processing means for calculating and storing a randomized back-off array for each of the plurality of subscriber home terminals, wherein the randomized back-off array is generated with a two-stage back-off retry algorithm,

a trunk line interconnecting the cable headend and the plurality of subscriber digital video home terminals through which messages from a subscriber can be sent to the cable headend and digital video can be sent to the subscriber,

and wherein each subscriber digital video home terminal includes means for receiving a randomized back-off array from the cable headend for controlling when a digital video home terminal attempts to send a message to the cable headend and then reattempts to send the message a plurality of times after a randomized back-off interval of time has passed after each reattempt until no collision would occur with another message generated from a different digital video home terminal.

14. A system according to claim 13 wherein each digital video home terminal includes means for initializing communication with the cable headend when the randomized back-off array is received from the cable headend.

15. A system according to claim 13 wherein a digital video home terminal includes Random Access Memory for storing the back-off array within the Random Access Memory of the digital video home terminal.

16. A system according to claim 13 wherein the back-off array received from the cable headend allows reattempted message transmissions after a respective time-out interval that comprises a first randomized interval of time and then allows reattempted message transmissions after a respective time-out period that comprises a second randomized interval of time.

17. A system according to claim 13 wherein the first randomized interval of time is calculated from a uniformly distributed retry algorithm and the second randomized interval of time is calculated from an exponential period of time.

18. A system according to claim 13 wherein said processor at the cable headend includes means for generating an acknowledgement to a subscriber digital video home terminal after the cable headend has received a message from the digital video home terminal.

19. A system according to claim 13 wherein said digital video home terminal includes means responsive to when an acknowledgement is not received so that a digital video home terminal reattempts a message transmission to the cable headend pursuant to a calculated random back-off interval of time.

20. A system according to claim 13 wherein said trunk line interconnecting the cable headend and the plurality of subscriber digital video home terminals comprises an RF Trunk line.