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

• US 8,432,863 B2
• Filed: 02/28/2011
• Issued: 04/30/2013
• Est. Priority Date: 05/12/2000
• Status: Expired due to Fees

• Current Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Original Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Inventors: Chuang, Justin Che-I, Leung, Kin K, Wang, Li-Chun
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): Mohebbi, Kouroush
• Application Number:
  US13/037,306
• Publication Number:
  US 20110149788A1
• Time in Patent Office: 792 Days
• Field of Search: None
• US Class Current: 370/329
• 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 executed in a base station that interacts with terminals, comprising the steps of:

determining range of signal path gains for said terminals,

dividing said range into a plurality of gain non-overlapping intervals, each having a lower boundary signal path gain and an upper boundary signal path gain;

assigning to each interval those of said terminals (group of terminals) that have a signal path gain between the lower and upper boundaries of said each interval;

specifying an associated modulation level to the group of terminals that are assigned to each of the intervals, to be used by said terminals when transmitting to said base station,

for each group of terminals, based on every set of K packets that are received from terminals in said each group,

computing an associated group packet error rate, which is a collective packet error rate of said group of terminals as experienced at said base station; and

specifying to the terminals in said group of terminals to modify their mode of operation in a direction that decreases throughput of data from said terminals, if the computed associated group packet error rate is above a specified group packet error rate.

2. The method of claim 1 where said intervals are chosen based on number of modulation levels that may be employed.

3. The method of claim 1 where said intervals are chosen to include a number of terminals that is not lower than a preselected number.

4. The method of claim 1 where said step of specifying to the terminals in said group to modify their mode of operation includes specifying, a power level at which to transmit.

5. The method of claim 4 where said power level for each of the terminals in said group is adjusted to achieve a target signal-to-interference-to-noise ratio.

6. The method of claim 5 where, following computing said power level for each of the terminals in said each group, computing an average power for said groups of terminals, and stepping up the modulation level of the terminals in said group by one level if the computed average power is less than a preselected level.

7. The method of claim 1 where said step of specifying to the terminals in said group of terminals to modify their mode of operation includes specifying a current modulation level for said each group of terminals.

8. The method of claim 1 where said specifying to the terminals in said group to modify their mode of operation includes specifying both a current modulation level for said group of terminals and transmission power by said terminals.

9. The method of claim 1 where said step of specifying to the terminals in said group of terminals to modify their mode of operation includes modifying the mode of operation in a direction that increases throughput of data from said terminals.

10. The method of claim 1 where said step of specifying an associated modulation level specifies a different modulation level to the groups of terminals that are assigned to the different intervals.