Method For Channel Congestion Management

• US 20070110098A1
• Filed: 10/03/2006
• Published: 05/17/2007
• Est. Priority Date: 12/09/2003
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Miller, Mark, Hart, Steven, Pateros, Charles
• Granted Patent: US 7,650,379 B2
• Time in Patent Office: Days
• US Class Current: 370/464
• CPC Class Codes: H04B 7/18543 for adaptation of transmission parameters, e.g. power control for detecting or preventing errors in the information received H04L1/00
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/12 Avoiding congestion; Recovering from congestion
• CPC Class Codes: H04L 47/13 in a LAN segment, e.g. ring or bus
• CPC Class Codes: H04L 47/25 with rate being modified by the source upon detecting a change of network conditions

Abstract

A method for managing data traffic in a multi-user multiple-simultaneous-access (MUMSA) environment, for example in a code reuse multiple access (CRMA) environment or other physical environment having true random access with more than one transmission present at the same time, the method including estimating channel load for multiple users, then using the estimate of channel load to calculate a congestion threshold on an ongoing basis, at each terminal performing an experiment using that congestion threshold value and a random number generator to determine if a packet is eligible to be transmitted, transferring downstream virtual channel traffic and redistributing user terminals to affiliate with the proper downstream virtual channel.

Claims

1. In a two-way satellite communication system having a plurality of upstream channels for communicating information from a plurality of subscriber terminals to a gateway hub and a plurality of virtual downstream channels for communicating information from the gateway to a selection of the subscriber terminals, a method for managing data traffic in the satellite communication system having true random access with more than one transmission present at the same time, the method comprising the steps of:

transmitting information as data on one of the virtual downstream channels in response to information transmitted on at least one of the upstream channels;

estimating channel load of multiple users in multiple simultaneous access in the upstream channels;

calculating on an ongoing basis a congestion threshold value using said estimate of channel load;

selecting a current congestion threshold value;

then at each said subscriber terminal, performing an experiment comparing the congestion threshold value with a random number to obtain a transmission value determinative of whether a packet is eligible to be transmitted by each said terminal; and

regulating the transmission of packets in the upstream channels according to said transmission value so that the transmitted load from all said terminals has a rate of packet transmission that is less than the congestion threshold value times the offered load to the terminal, and the virtual downstream channels bear a more evenly distributed load.

2. The method according to claim 1 wherein said estimate of channel load is probability of access and said the congestion threshold value is related to the probability of a globally successful transmission of a number of simultaneously transmitted packets.

3. The method according to claim 2 further including the step of, at each said terminal, throttling the channel load according to a quality of service factor.

4. The method according to claim 3 wherein said congestion threshold is broadcast and said quality of service factor is broadcast at least as frequently as a congestion threshold value.

5. The method according to claim 1 wherein a quality of service factor is committed to each said terminal for use in additionally throttling the channel load and assuring transmission of selected packets.

6. The method according to claim 1 wherein said estimating of channel load is at a hub where traffic of multiple users is monitored.

7. The method according to claim 6 wherein said estimate of channel load is probability of access and said the congestion threshold value is related to the probability of a globally successful transmission of a number of simultaneously transmitted packets.

8. The method according to claim 6 further including the step of, at each said terminal, throttling the channel load according to a quality of service factor.

9. The method according to claim 8 wherein said congestion threshold is broadcast and said quality of service factor is broadcast at least as frequently as a congestion threshold value.

10. The method according to claim 6 wherein a quality of service factor is committed to each said terminal for use in additionally throttling the channel load and assuring transmission of selected packets.

11. A method for managing data traffic in a multiple-user environment having true random access with more than one transmission present at the same time, the method comprising the steps of:

receiving signals from said multiple users;

calculating on an ongoing basis a congestion threshold value using an estimate of channel load;

selecting a current congestion threshold value;

then

at each said terminal, performing an experiment comparing the congestion threshold value with a random number to obtain a transmission value determinative of whether a packet is eligible to be transmitted by each said terminal; and

transmitting packets through a terminal while throttling the random transmission of packets according to said transmission value so that the transmitted load from all said terminals has a rate of packet transmission that is less than the congestion threshold value times the offered load to the terminal.

12. A method for managing data traffic in a multiple-user environment having true random access with more than one transmission present at the same time, the method comprising the steps of:

receiving signals from said multiple users;

calculating on an ongoing basis a congestion threshold value using an estimate of channel load;

selecting a current congestion threshold value;

then

at each said terminal, performing an experiment comparing the congestion threshold value with a random number to obtain a transmission value determinative of whether a packet is eligible to be transmitted by each said terminal;

assigning users of a potentially congested virtual downstream channel to another virtual downstream channel to which the downstream packet streams have been reassigned, and

receiving the reassigned packet streams.

13. The method according to claim 12, wherein each virtual downstream channel has a one to one relationship with an upstream channel.

14. The method according to claim 12 wherein each virtual downstream channel has a one to many relationship with affiliated upstream channels.

15. The method according to claim 12 wherein terminals are grouped into upstream channels according to at least one of:

capability, level of service, frequency band, and speed of transmission to effect the creation a group of upstream channels unaffiliated with any downstream channel;

and managing the operation of the terminals.