POWER CONTROL FOR A WIRELESS COMMUNICATION SYSTEM UTILIZING ORTHOGONAL MULTIPLEXING

• US 20080214121A1
• Filed: 05/15/2008
• Published: 09/04/2008
• Est. Priority Date: 06/18/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Agrawal, Avneesh, Sutivong, Arak, Julian, David Jonathan
• Granted Patent: US 8,478,202 B2
• Time in Patent Office: Days
• US Class Current: 455/67.13
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 28/04 Error control
• CPC Class Codes: H04W 52/125 cascaded outer loop power control
• CPC Class Codes: H04W 52/146 Uplink power control
• CPC Class Codes: H04W 52/16 Deriving transmission power values from another channel
• CPC Class Codes: H04W 52/20 using error rate
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/241 taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo
• CPC Class Codes: H04W 52/242 taking into account path loss
• CPC Class Codes: H04W 52/243 taking into account interferences
• CPC Class Codes: H04W 52/247 where the output power of a terminal is based on a path parameter sent by another terminal
• CPC Class Codes: H04W 52/283 Power depending on the position of the mobile
• CPC Class Codes: H04W 52/36 with a discrete range or set of values, e.g. step size, ramping or offsets
• CPC Class Codes: H04W 52/362 Aspects of the step size
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/54 Signalisation aspects of the TPC commands, e.g. frame structure
• CPC Class Codes: H04W 52/60 : using different transmission rates for TPC commands
• CPC Class Codes: H04W 88/08 : Access point devices

Abstract

Techniques for adjusting transmit power to mitigate both intra-sector interference to a serving base station and inter-sector interference to neighbor base stations are described. The amount of inter-sector interference that a terminal may cause may be roughly estimated based on the total interference observed by each neighbor base station, channel gains for the serving and neighbor base stations, and the current transmit power level. The transmit power may be decreased if high interference is observed by a neighbor base station and increased otherwise. The transmit power may be adjusted by a larger amount and/or more frequently if the terminal is located closer to the neighbor base station observing high interference and/or if the current transmit power level is higher, and vice versa. The intra-sector interference is maintained within an acceptable level by limiting a received SNR for the terminal to be within a range of allowable SNRs.

Claims

1. A method of reporting interference in a wireless communication system, comprising:

estimating interference observed at a base station;

forming an interference report for the estimated interference; and

broadcasting the interference report via a wireless channel.

2. The method of claim 1, wherein the interference does excludes signal power received for terminals transmitting to the base station.

3. The method of claim 1, further comprising:

comparing the estimated interference against a first interference threshold; and

setting a first bit based on whether the estimated interference is above or below the first interference threshold, and wherein the interference report comprises the first bit.

4. The method of claim 3, further comprising:

comparing the estimated interference against a second interference threshold that is higher than the first interference threshold; and

setting a second bit based on whether the estimated interference is above or below the second interference threshold, and wherein the interference report further comprises the second bit.

5. The method of claim 1, wherein the estimating interference observed at a base station comprises

obtaining an interference estimate for each of a plurality of subbands at the base station, and

deriving the estimated interference based on a plurality of interference estimates for the plurality of subbands.

6. The method of claim 5, wherein the estimated interference is an arithmetic average of the plurality of interference estimates for the plurality of subbands.

7. The method of claim 5, wherein the estimated interference is a geometric average of the plurality of interference estimates for the plurality of subbands.

8. The method of claim 5, wherein the estimated interference is obtained based on a capacity-based averaging of the plurality of interference estimates for the plurality of subbands.

9. An apparatus in a wireless communication system, comprising:

an interference estimator operative to estimate interference observed at a base station;

a controller operative to form an interference report for the estimated interference; and

a data processor operative to process the interference report for broadcast via a wireless channel.

10. The apparatus of claim 9, wherein the controller is operative to compare the estimated interference against an interference threshold and to set a bit based on whether the estimated interference is above or below the interference threshold, and wherein the interference report comprises the bit.

11. An apparatus in a wireless communication system, comprising:

means for estimating interference observed at a base station;

means for forming an interference report for the estimated interference; and

means for broadcasting the interference report via a wireless channel.

12. The apparatus of claim 11, further comprising:

means for comparing the estimated interference against an interference threshold; and

means for setting a bit based on whether the estimated interference is above or below the interference threshold, and wherein the interference report comprises the bit.