System and method for estimating interference in a packet-based wireless network

• US 20090010242A1
• Filed: 09/12/2008
• Published: 01/08/2009
• Est. Priority Date: 08/02/2002
• Status: Active Grant

• Current Assignee: AT&T Intellectual Property II LP (AT&T, Inc.)
• Original Assignee: AT&T Intellectual Property II LP (AT&T, Inc.)
• Inventors: Winters, Jack Harriman, Leung, Kin K.
• Granted Patent: US 8,155,097 B2
• Time in Patent Office: Days
• US Class Current: 370/345
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/206 for modulated signals
• CPC Class Codes: H04W 52/223 predicting future states of the transmission
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters

Abstract

A system and method for predicting future interference power in packet-switched networks is disclosed, allowing improved performance in such networks via optimized link adaptation and power control. In an embodiment for use in a cellular network, Kalman filtering can be used to provide the interference estimation through identification of the number of active co-channel interferers in the cellular networks and correlation of the interference power with the number of active interferers. A two-dimensional Kalman filter can be used to exploit that correlation to enhance prediction accuracy. In an alternative embodiment, a one-dimensional Kalman filter can be used where the number of active interferers is not considered.

Claims

1. A method for estimating interference power at a receiver in a wireless network communications system to select a transmission power between a transmitter and the receiver, comprising:

at the receiver, determining a number of active interferers transmitting in a first time slot to the receiver;

at the receiver, measuring an interference power value for said first time slot;

at the receiver, estimating an interference power value for a second time slot and a number of active interferers for said second time slot by correlating said measured interference power value and said number of active interferers for said first time slot; and

selecting a transmission power for transmission between said transmitter and said receiver over said second time slot as a function of said estimated interference power and number of active interferers.

2. A method as in claim 1, further comprising using a two-dimensional Kalman filter to estimate the interference power value and the number of active interferers.

3. A method as in claim 1, further comprising:

measuring the total received power for said first time slot;

measuring the power of a transmitted signal for the first time slot; and

subtracting said power of said transmitted signal from said total received power.

4. A method as in claim 1, wherein said wireless network further comprises a packet-based network system.

5. A method as in claim 1, wherein said receiver further comprises a base station.

6. A method as in claim 1, wherein said receiver further comprises a terminal.

7. An interference power estimation apparatus for a receiver in a wireless network for selecting a transmission power between a transmitter and the receiver, comprising:

means for determining a number of active interferers transmitting in a first time slot to the receiver;

means for measuring an interference power value for said first time slot; and

means for estimating an interference power value for a second time slot and number of active interferers for said second time slot by correlating said measured interference power value and said number of active interferers for said first time slot; and

means for selecting a transmission power for transmission between said transmitter and said receiver in said second time slot as function of the estimated interference power value and number of active interferers.

8. An apparatus as in claim 7, wherein said wireless network further comprises a packet-based network system.

9. An apparatus as in claim 7, wherein said receiver further comprises a base station.

10. An apparatus as in claim 7, wherein said receiver further comprises a terminal.

11. An apparatus as in claim 7, wherein said means for measuring further comprises a two-dimensional Kalman filter.

12. A computer-readable medium containing computer program instructions which, when executed by a processor, enable a receiver in a wireless network communications system to estimate interference power to enable a transmitter to transmit to the receiver at a transmission power that is a function of the estimated interference power, by:

determining a number of active interferers that are transmitting in a first time slot to the receiver;

measuring an interference power value for said first time slot;

estimating an interference power value for a second time slot and number of active interferers for said second time slot by correlating said measured interference power and said number of active interferers for said first time slot; and

calculating a transmission power for transmission between said transmitter and said receiver in said second time slot as a function of the estimated interference power value and number of active interferers.

13. A computer-readable medium as in claim 12, wherein said computer program instructions, when executed by the processor, further enable said receiver to estimate the interference power value and the number of active interferers based on said received signal power using a two-dimensional Kalman filter.

14. A computer-readable medium as in claim 12, wherein said computer program instructions, when executed by the processor, further enable said receiver to measure interference power for said first time slot by:

measuring the total received power for said first time slot;

measuring the power of a transmitted signal; and

subtracting said power of said transmitted signal from said total received power.

15. A computer-readable medium as in claim 12, wherein said wireless network further comprises a packet-based network system.

16. A computer-readable medium as in claim 12, wherein said receiver further comprises a base station.

17. A computer-readable medium as in claim 12, wherein said receiver further comprises a terminal.

18. A method comprising:

determining a number of active interferers for a first time slot;

measuring interference power for said first time slot;

predicting interference power for a second time slot and number of active interferers for a second time slot by correlating said measured interference power and said number of active interferers; and

selecting a transmission power for the second time slot based on the predicted interference power value for the second time slot in order to provide power control in a wireless network communications system.

19. A method as in claim 18, further comprising using a two-dimensional Kalman filter to estimate interference power and the number of active interferers.

20. A method for link adaptation between a transmitter and receiver in a wireless network, comprising:

determining a number of active interferers for a first time slot;

measuring interference power for said first time slot;

predicting interference power for a second time slot and number of active interferers for a second time slot by correlating said measured interference power and said number of active interferers;

estimating signal path gain between the transmitter and receiver;

selecting a transmission power for the second time slot based on the predicted interference power value for the second time slot;

estimating the signal to interference ratio for the second time slot using the selected transmission power, estimated signal path gain and predicted interference power, in order to determine a data rate and modulation level for the link between the transmitter and receiver.