Method and system for integrated link adaptation and power control to improve error and throughput performance in wireless packet networks

• US 20090175192A1
• Filed: 03/10/2009
• Published: 07/09/2009
• Est. Priority Date: 05/12/2000
• Status: Active Grant

• Current Assignee: AT&T Corporation (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Leung, Kin K., Wang, Li-Chun, Chuang, Justin Che-I
• Granted Patent: US 7,920,505 B2
• Time in Patent Office: Days
• US Class Current: 370/253
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0015 characterised by the adaptation strategy
• CPC Class Codes: H04L 1/0019 in which mode-switching is based on a statistical approach
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 28/04 Error control
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 4/08 User group management
• CPC Class Codes: H04W 52/20 using error rate

Abstract

The invention provides a system that implements an algorithm for integrated link adaptation and power control to achieve specified error rates and to improve an overall throughput for real-time applications in wireless packet networks. The system initially divides wireless terminals into groups according to their signal path gains. Afterwards, the system can periodically adapt transmissions (i.e., link adaptations) based on the required error rates, actual error statistics and average transmission power for each wireless terminal group. Furthermore, transmission power can be adjusted by an enhanced Kalman-filter method to ensure successful reception.

Claims

1. A method for improving error performance and throughput performance between a base station and a collection of wireless terminals communicating with said base station, comprising:

dividing said collection of wireless terminals into a plurality of groups, at least one of the groups including two or more wireless terminals; and

configuring, for each of the groups, a modulation level for communication between said base station and said wireless terminals.

2. The method according to claim 1 where said dividing is based on signal path gains.

3. The method according to claim 1, further comprising:

adjusting a transmission power level for wireless terminals in each group according to the configured modulation level for the group.

4. The method according to claim 2, wherein the transmission power level for the individual wireless terminals in each group is adjusted to achieve substantially the same error performance for the wireless terminals of the same group.

5. The method according to claim 2, wherein adjusting a transmission power level for wireless terminals in each group includes an adjustment of a signal-to-interference-noise ratio (SINR) target in power control to ensure satisfactory error performance for the individual wireless terminals.

6. The method according to claim 1, wherein adapting a modulation level for each of the groups is performed periodically after receiving a predetermined number of packets from said collection of wireless terminals.

7. The method according to claim 1, wherein adapting a modulation level for each of the groups is performed periodically after transmitting a predetermined number of packets to the wireless terminals.

8. The method according to claim 1, wherein adapting a modulation level for each of the groups is based on a transmission power statistic.

9. The method according to claim 1, wherein adapting a modulation level for each of the groups is based on a measured error performance of the group.

10. An apparatus for improving error performance and throughput performance of a cellular network, comprising:

a controller in a base station of a cell in said cellular network that divides a plurality of wireless terminals that communicate with said base station into a plurality of groups, based on signal path gains, at least one of the groups including two or more wireless terminals, and that adapts a modulation level for each of the groups.

11. The apparatus according to claim 12, wherein the controller further adjusts a transmission power level for wireless terminals in each group according to the adapted modulation for the group.

12. The apparatus according to claim 13, wherein the transmission power level for the individual wireless terminals in each group is adjusted to achieve substantially the same error performance for the wireless terminals of the same group.

13. The apparatus according to claim 13, wherein adjusting a transmission power-level for wireless terminals in each group includes a minor adjustment of a signal-to-interference-noise ratio (SINR) target in power control to ensure satisfactory error performance for the individual wireless terminals.

14. The apparatus according to claim 12, wherein adapting a modulation level for each of the groups is performed periodically after receiving a predetermined number of packets from the wireless terminals.

15. The apparatus according to claim 12, wherein adapting a modulation level for each of the groups is performed periodically after transmitting a predetermined number of packets to the wireless terminals.

16. The apparatus according to claim 12, wherein adapting a modulation level for each of the groups is based on a measured error performance of the group.