Leader-follower power control

• US 7,580,673 B2
• Filed: 08/07/2006
• Issued: 08/25/2009
• Est. Priority Date: 07/30/2004
• Status: Active Grant

• Current Assignee: ViaSat Incorporated
• Original Assignee: ViaSat Incorporated
• Inventors: O'Neill, John H., Miller, Mark J.
• Primary Examiner(s): Phu; Sanh D
• Application Number:
  US11/462,811
• Publication Number:
  US 20060270442A1
• Time in Patent Office: 1,114 Days
• Field of Search: 455/13.4, 455/10, 455/69, 455/427, 455/522, 375/320, 375/321
• US Class Current: 455/13.4
• CPC Class Codes: H04B 7/18513 Transmission in a satellite or space-based system
• 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: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/245 taking into account received signal strength
• CPC Class Codes: H04W 52/46 in multi hop networks, e.g. wireless relay networks

Abstract

In a satellite or other relayed communication system having a plurality of subscriber terminals that communicate through an elevated wireless relay (typically a satellite operating in bent pipe mode), a technique for subscriber terminal power control is provided whereby the power level is controlled via leader-follower operation relying on sharing control factors determined at a single calibrated subscriber terminal transmitter (the leader terminal) to create traffic to be compared to the received traffic of the other subscriber terminals. The power level of the subscriber terminals is then adjusted based on the relationship of their received energy to the received energy of the leader terminal.

Claims

1. In a communication system having a hub and a plurality of subscriber terminals coupled for communication with one another via relay satellite operative in a bent pipe mode through a forward uplink path from the hub, a forward downlink path to the subscriber terminals, a return uplink path from the subscriber terminals, and a return downlink path to the hub, a method for transmit power level control at the subscriber terminals comprising:

providing a calibrated transmit signal terminal operative as a leader terminal and having a leader downlink propagation path that represents subscriber terminal downlink propagation paths;

causing the leader terminal to calibrate its power level using power levels of at least said leader downlink propagation path;

measuring subscriber terminal power levels;

comparing the respective subscriber terminal power levels with the leader terminal power level to produce an error signal; and

using the error signal to produce a control signal to control the transmit power level of the subscriber terminals.

2. The method according to claim 1 wherein the comparing step is operative at the hub.

3. The method according to claim 2 wherein the hub communicates at least one of an error signal and a control signal to the subscriber terminals.

4. The method according to claim 1 wherein the comparing step is performed at each subscriber terminal.

5. The method according to claim 4 wherein the hub communicates at least a measured specific subscriber terminal power level to each corresponding specific subscriber terminal.

6. The method according to claim 5 wherein the error signal using step is performed at the subscriber terminal.

7. The method according to claim 5 estimating leader terminal power level received at the hub and communicating the leader terminal power level estimate to subscriber terminals via the forward downlink.

8. The method according to claim 1 wherein the leader terminal is collocated with the hub.

9. The method according to claim 1 wherein the leader terminal is remotely located away from the hub.

10. A subscriber terminal for use in a satellite communication system having a leader terminal and a plurality of subscriber terminals coupled for communication with one another via a relay satellite having a forward downlink path to the subscriber terminals, a return uplink path from the subscriber terminals, a return leader downlink path to the leader terminal, and a transmitter at the leader terminal operative to generate power level testing signals on a leader uplink path, the subscriber terminal comprising:

a receiver operative to receive error and control information for use in adjusting transmit power levels;

a control system for controlling transmit power level on its own return uplink path in response to said error information, said error information comparing leader terminal transmit signals and self transmitted signals on the return leader downlink path; and

a transmitter coupled to said control system for generating power level adjusted signals on said own return uplink path such that output power of a relay downlink signal is a function of input power of a relay uplink signal received by the relay apparatus from the leader terminal.

11. The subscriber terminal according to claim 10 wherein the receiver is operative to receive the error and control information via the forward downlink path.

12. The subscriber terminal according to claim 10 wherein the receiver is operative receive a leader terminal power level estimate and a measured subscriber terminal power level, and wherein the control system is operative to compare the leader terminal power level estimate and the measured subscriber terminal power level to formulate return uplink power level control.

13. The subscriber terminal according to claim 10 wherein the receiver is configured to receive an error signal based on the leader terminal power level estimate and the measured subscriber terminal power level;

and wherein the control system is configured to formulate return uplink power level control.

14. The subscriber terminal according to claim 10 wherein the receiver is operative receive a control signal and wherein the control system is operative to regulate return uplink power level in response to the control signal.