Estimation of thermal noise and rise-over-thermal in a wireless communication system

• US 8,254,279 B2
• Filed: 04/21/2008
• Issued: 08/28/2012
• Est. Priority Date: 04/24/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wheatley, Charles E. III, Agrawal, Avneesh, Zhang, Danlu, Sambhwani, Sharad Deepak, Yuan, Lu, Iraninejad, Mehraban
• Primary Examiner(s): Ferris, Derrick
• Assistant Examiner(s): BROCKMAN, ANGEL T
• Application Number:
  US12/107,013
• Publication Number:
  US 20080267086A1
• Time in Patent Office: 1,590 Days
• Field of Search: 370/252, 370/328
• US Class Current: 370/252
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336
• CPC Class Codes: H04B 17/382 for resource allocation, admission control or handover

Abstract

Techniques for estimating thermal noise and rise-over-thermal (RoT) in a communication system are described. In an aspect, thermal noise in a sideband may be measured and used to estimate thermal noise in a signal band. In one design, received power in the sideband may be measured, e.g., by computing total power of FFT transform coefficients within the sideband. Thermal noise may be estimated based on (e.g., by filtering) the measured received power in the sideband. Received power in the signal band may also be measured. Total received power may be estimated based on (e.g., by filtering) the measured received power in the signal band. RoT may then be estimated based on the estimated thermal noise and the estimated total received power. The estimated RoT may be used to estimate an available load for a cell, which may be used to admit and/or schedule users in the cell.

Claims

1. A method of estimating thermal noise in a communication system, comprising:

measuring received power in a signal band;

measuring received power in a sideband outside of the signal band;

estimating total received power based on the measured received power in the signal band; and

estimating, by a processor, thermal noise in the signal band based on the measured received power in the sideband, wherein the sideband comprises guard subcarriers and the signal band comprises usable subcarriers among plurality of subcarriers.

2. The method of claim 1, wherein the measuring the received power in the sideband comprises

partitioning samples into blocks, each block comprising N samples, where N is greater than one,

transforming each block of N samples to obtain a corresponding block of N transform coefficients, and

computing total power of transform coefficients within the sideband to obtain the measured received power in the sideband.

3. The method of claim 1, wherein the estimating the thermal noise comprises filtering the measured received power in the sideband to obtain the estimated thermal noise.

4. The method of claim 1, wherein the estimating the thermal noise comprises filtering the measured received power in the sideband with an infinite impulse response (IIR) filter to obtain the estimated thermal noise.

5. The method of claim 1, wherein the estimating the thermal noise comprises averaging the measured received power in the sideband over a sliding window of a predetermined length to obtain the estimated thermal noise.

6. The method of claim 1, further comprising:

estimating rise-over-thermal (RoT) based on the estimated thermal noise and the estimated total received power.

7. The method of claim 6, wherein the estimating the RoT comprises computing the RoT based on the estimated thermal noise, the estimated total received power, the sideband, and an effective signal band for the total received power.

8. The method of claim 6, further comprising:

estimating an available load for a cell based on the estimated RoT; and

performing scheduling and admission control based on the available load.

9. The method of claim 6, further comprising:

reporting the estimated thermal noise or the estimate RoT, or both, to a network controller.

10. The method of claim 7, wherein the estimating the RoT comprises

computing the RoT based further on a calibration factor selected to provide a predetermined RoT value when no signal is applied.

11. The method of claim 8, wherein the performing scheduling and admission control comprises

selecting a user to admit or schedule,

determining a load of the selected user, and

updating the available load based on the load of the selected user.

12. The method of claim 1, wherein the measuring the received power in the signal band comprises

partitioning samples into blocks, each block comprising N samples, where N is greater than one,

transforming each block of N samples to obtain a corresponding block of N transform coefficients, and

computing total power of transform coefficients within the signal band to obtain the measured received power in the signal band.

13. The method of claim 12, wherein the measuring the received power in the signal band further comprises

filtering each block of N transform coefficients with a matched filter to obtain a corresponding block of N filtered coefficients, and

computing total power of filtered coefficients within the signal band to obtain the measured received power in the signal band.

14. The method of claim 1, wherein the estimating the total received power comprises filtering the measured received power in the signal band to obtain the estimated total received power.

15. The method of claim 1, further comprising:

amplifying an analog input signal to obtain an amplified signal having a thermal noise floor higher than quantization noise of an analog-to-digital converter (ADC);

digitizing the amplified signal with the ADC to obtain samples; and

measuring the received power in the sideband based on the samples.

16. The method of claim 1, wherein location of the sideband is selected based on frequency spacing between adjacent CDMA channels.

17. The method of claim 1, further comprising:

estimating interference-over-thermal (IoT) based on the estimated thermal noise.

18. An apparatus for wireless communication, comprising:

at least one processor

to measure received power in a signal band,

to measure received power in a sideband outside of the signal band,

to estimate total received power based on the measured received power in the signal band,

to estimate thermal noise in the signal band based on the measured received power in the sideband, wherein the sideband comprises guard subcarriers and the signal band comprises usable subcarriers among plurality of subcarriers.

19. The apparatus of claim 18, wherein the at least one processor partitions samples into blocks, each block comprising N samples, where N is greater than one, transforms each block of N samples to obtain a corresponding block of N transform coefficients, and computes total power of transform coefficients within the sideband to obtain the measured received power in the sideband.

20. The apparatus of claim 18, wherein the at least one processor filters the measured received power in the sideband to obtain the estimated thermal noise.

21. The apparatus of claim 18, wherein the at least one processor estimates rise-over-thermal (RoT) based on the estimated thermal noise and the estimated total received power.

22. The apparatus of claim 21, wherein the at least one processor partitions samples into blocks, each block comprising N samples, where N is greater than one, transforms each block of N samples to obtain a corresponding block of N transform coefficients, and computes total power of transform coefficients within the signal band to obtain the measured received power in the signal band.

23. The apparatus of claim 21, wherein the at least one processor estimates an available load for a cell based on the estimated RoT, and performs scheduling and admission control based on the available load.

24. An apparatus comprising:

means for measuring received power in a signal band;

means for measuring received power in a sideband outside of the signal band;

means for estimating total received power based on the measured received power in the signal band; and

means for estimating thermal noise in the signal band based on the measured received power in the sideband, wherein the sideband comprises guard subcarriers and the signal band comprises usable subcarriers among plurality of subcarriers.

25. The apparatus of claim 24, wherein the means for measuring the received power in the sideband comprises

means for partitioning samples into blocks, each block comprising N samples, where N is greater than one,

means for transforming each block of N samples to obtain a corresponding block of N transform coefficients, and

means for computing total power of transform coefficients within the sideband to obtain the measured received power in the sideband.

26. The apparatus of claim 24, wherein the means for estimating the thermal noise comprises means for filtering the measured received power in the sideband to obtain the estimated thermal noise.

27. The apparatus of claim 24, further comprising:

means for estimating rise-over-thermal (RoT) based on the estimated thermal noise and the estimated total received power.

28. The apparatus of claim 27, further comprising:

means for estimating an available load for a cell based on the estimated RoT; and

means for performing scheduling and admission control based on the available load.

29. The apparatus of claim 24, wherein the means for measuring the received power in the signal band comprises

means for partitioning samples into blocks, each block comprising N samples, where N is greater than one,

means for transforming each block of N samples to obtain a corresponding block of N transform coefficients, and

means for computing total power of transform coefficients within the signal band to obtain the measured received power in the signal band.