SYSTEM FOR CHANNEL CONGESTION MANAGEMENT

• US 20100008225A1
• Filed: 09/21/2009
• Published: 01/14/2010
• Est. Priority Date: 12/09/2003
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: Pateros, Charles N., Miller, Mark J., Hart, Steven R.
• Granted Patent: US 7,975,008 B2
• Time in Patent Office: Days
• US Class Current: 370/232
• 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 system 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 system including a channel load estimator for multiple users, a congestion threshold calculator using the estimate of channel load to calculate threshold on an ongoing basis, a tester 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, a traffic controller for transferring downstream virtual channel traffic and a redistributing mechanism for redistributing user terminals to affiliate with the proper downstream virtual channel.

Claims

1. A system for managing traffic in a two-way satellite communication system comprising:

an upstream transmitter for transmitting via a multiple user multiple simultaneous access (MUMSA) upstream channel having true random access with more than one transmission present at the same time;

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

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

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

a selector for selecting a current congestion threshold value and for directing the transmitting of the current congestion threshold value on a downstream channel to a plurality of subscriber terminals;

a tester at each of the plurality of subscriber terminals for 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

a regulator for regulating the transmission of packets in the MUMSA upstream channels according at least in part to the 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 system 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 system 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 system 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 system 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 system according to claim 1 wherein said estimating of channel load is at a hub where traffic of multiple users is monitored.

7. The system 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 system according to claim 6 further including a throttle, at each said terminal, for throttling the channel load according to a quality of service factor.

9. The system 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 system 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. The system according to claim 1 wherein a quality of service factor controls the throttling of the transmitted load from each said terminal.

12. The system according to claim 1 wherein the tester determines whether the packets are transmitted or discarded.

17. The system 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.

13. A system for managing traffic in a multiple-user two-way satellite communication system comprising:

a transmitter transmitting with true random access in the presence of more than one transmission present at the same time;

a receiver for receiving signals from said multiple users;

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

a selector for selecting a current congestion threshold value and for directing the transmitting of the current congestion threshold value on a downstream channel to a plurality of subscriber terminals;

a tester at each of the plurality of subscriber terminals for 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

a terminal for transmitting packets through 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.

14. A system for managing traffic in a multiple-user two-way satellite communication system comprising:

a transmitter transmitting with true random access in the presence of more than one transmission present at the same time;

a receiver for receiving signals from said multiple users;

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

a selector for selecting a current congestion threshold value and for directing the transmitting of the current congestion threshold value on a downstream channel to a plurality of subscriber terminals;

a tester at each of the plurality of subscriber terminals for 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

a controller for assigning users of a potentially congested virtual downstream channel to another virtual downstream channel to which the downstream packet streams have been reassigned.

15. The system according to claim 14, wherein each virtual downstream channel has a one to one relationship with an upstream channel.

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