Method and apparatus for power estimation in a communication system

• US 5,412,686 A
• Filed: 09/17/1993
• Issued: 05/02/1995
• Est. Priority Date: 09/17/1993
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Ling, Fuyun
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US08/123,452
• Time in Patent Office: 592 Days
• Field of Search: 370/32.1, 375/1, 342/463, 455/67.1
• US Class Current: 375/147
• CPC Class Codes: H04B 17/327 Received signal code power [RSCP]
• CPC Class Codes: H04W 52/04 TPC

Abstract

A method and apparatus is provided for estimating signal power. This is accomplished by demodulating a received communication signal to derive a stream of samples. These samples may consist of either reference samples, data samples, or a combination thereof. An estimate of the power of the received communication signal is then generated as a function of the stream of samples. The signal power estimate may, for example, be used in a power control algorithm by setting a power control indicator in response to a comparison between the signal power estimate and a predetermined threshold. Subsequently, the power control indicator is transmitted over a communication channel to another communication unit. The communication unit detects a power control indicator within a signal received from over the communication channel and adjusts a particular signal transmission power of a signal transmitter in response to the detected power control indicator.

Claims

1. An apparatus comprising a signal power estimator, the signal power estimator comprising:

(a) demodulating means for demodulating a received communication signal to derive a stream of samples selected from the group consisting of;

a stream of reference samples and a stream of data samples; and

(b) estimating means, operatively coupled to the demodulating means, for generating a complex signal power estimate of the power of the received communication signal as a function of the stream of samples.

2. The apparatus of claim 1 wherein the estimating means comprises means for generating a plurality of complex signal power estimates from the stream of reference samples by correlating a known reference sequence with the stream of reference samples.

3. The apparatus of claim 2 wherein the estimating means further comprises averaging means for averaging the plurality of complex signal power estimates together to form an average complex reference signal power estimate.

4. The apparatus of claim 3 wherein the estimating means further comprises means for generating a reference-based signal power estimate by calculating the magnitude of the average complex reference signal power estimate.

5. The apparatus of claim 1 wherein the estimating means comprises means for generating a plurality of complex squared data samples from the stream of data samples by complex squaring the stream of data samples.

6. The apparatus of claim 5 wherein the estimating means further comprises averaging means for averaging the plurality of complex squared data samples together to form an average complex squared data sample.

7. The apparatus of claim 6 wherein the estimating means further comprises means for generating a data-based signal power estimate by calculating the magnitude of the average complex squared data sample.

8. The apparatus of claim 1 wherein the estimating means comprises:

(a) average complex reference signal power estimate means for generating a plurality of complex signal power estimates from the stream of reference samples by correlating a known reference sequence with the stream of reference samples and averaging the plurality of complex signal power estimates together to form an average complex signal power estimate;

(b) average complex squared data sample means for generating a plurality of complex squared data samples from the stream of data samples by complex squaring the stream of data samples and averaging the plurality of complex squared data samples together to form an average complex squared data samples; and

(c) signal power estimate means, operatively coupled to the average complex reference signal power estimate means and the average complex squared data sample means, for calculating a magnitude of a linear combination of the average complex reference signal power estimate squared and the average complex squared data sample.

9. The apparatus of claim 1, further comprising means for determining a magnitude of the complex signal power estimate to produce a sample-based signal power estimate.

10. The apparatus of claim 9 further comprising a threshold means, operatively coupled to the signal power estimator, for setting a power control indicator in response to the result of a comparison between the sample-based signal power estimate and a predetermined threshold.

11. The apparatus of claim 10 further comprising a signal transmitting means, operatively coupled to the threshold means, for transmitting the power control indicator over a communication channel.

12. The apparatus of claim 11 wherein the signal transmitting means comprises means for preparing the power control indicator for transmission over the communication channel by spreading the power control indicator with a spreading code prior to transmission over the communication channel.

13. The apparatus of claim 11 wherein the communication channel is selected from the group consisting essentially of an electronic data bus, radio communication link, satellite communication link, wireline and optical fiber link.

14. The apparatus of claim 11 further comprising:

(a) signal receiving means for detecting a power control indicator within a signal received from over the communication channel; and

(b) power adjustment means, operatively coupled to the signal receiving means, for adjusting a particular signal transmission power of a signal transmitter in response to the detected power control indicator.

15. The apparatus of claim 14 wherein the signal receiving means comprises means for despreading the received signal with a spreading code to detect the power control indicator.

16. A communication unit, comprising:

(a) a signal power estimator including demodulating means for demodulating a received communication signal to derive a stream of samples selected from the group consisting of;

a stream of reference samples and a stream of data samples, estimating means, operatively coupled to the demodulating means, for generating a complex signal power estimate of the power of the received communication signal as a function of the stream of samples, and means for determining a magnitude of the complex signal power estimate to produce a sample-based signal power estimate;

(b) threshold means, operatively coupled to the signal power estimator, for setting a power control indicator in response to the result of a comparison between the sample-based signal power estimate and a predetermined threshold; and

(c) signal transmitting means, operatively coupled to the threshold means, for transmitting the power control indicator over a communication channel.

17. The apparatus of claim 16 wherein the signal transmitting means comprises means for preparing the power control indicator for transmission over the communication channel by spreading the power control indicator with a spreading code prior to transmission over the communication channel.

18. A communication unit, comprising:

(a) signal receiving means for detecting a power control indicator within a signal received from over it communication channel, the power control indicator being derived from a comparison between a sample-based signal power estimate and a predetermined threshold, the sample-based signal power estimate being derived from it magnitude of a complex signal power estimate of a power of a despread communication signal as a function of a stream of samples selected from the group consisting of;

a stream of reference samples and a stream of data samples;

(b) power adjustment means, operatively coupled to the signal receiving means, for adjusting a particular signal transmission power of a signal transmitter in response to the detected power control indicator.

19. The apparatus of claim 18 wherein the signal receiving means comprises means for despreading the received signal with a spreading code to detect the power control indicator.

20. A method of estimating signal power, comprising:

(a) demodulating a received communication signal to derive a stream of samples selected from the group consisting of;

a stream of reference samples and a stream of data samples; and

(b) generating a complex signal power estimate of the power of the received communication signal as a function of the stream of samples.

21. The method of claim 20, further comprising the step of determining a magnitude of the complex signal power estimate to produce a sample-based signal power estimate.

22. The method of claim 20 wherein the generating step comprises generating a plurality of complex signal power estimates from the stream of reference samples by correlating a known reference sequence with the stream of reference samples.

23. The method of claim 22 further comprising a step of averaging the plurality of complex signal power estimates together to form an average complex reference signal power estimate.

24. The method of claim 23 further comprising a step of generating a reference-based signal power estimate by calculating the magnitude of the average complex reference signal power estimate.

25. The method of claim 20 wherein the generating step comprises generating a plurality of complex squared data samples from the stream of data samples by complex squaring the stream of data samples.

26. The method of claim 25 further comprising a step of averaging the plurality of complex squared data samples together to form an average complex squared data sample.

27. The method of claim 26 further comprising a step of generating a data-based signal power estimate by calculating the magnitude of the average complex squared data sample.

28. The method of claim 20 wherein the generating step comprises the steps of:

(a) generating a plurality of complex signal power estimates from the stream of reference samples by correlating a known reference sequence with the stream of reference samples and averaging the plurality of complex signal power estimates together to form an average complex signal power estimate;

(b) generating a plurality of complex squared data samples from the stream of data samples by complex squaring the stream of data samples and averaging the plurality of complex squared data samples together to form an average complex squared data samples; and

(c) calculating a magnitude of a linear combination of the average complex reference signal power estimate squared and the average complex squared data sample.

29. The method of claim 21 further comprising the step of setting a power control indicator in response to the result of a comparison between the sample-based signal power estimate and a predetermined threshold.

30. The method of claim 29 further comprising a step of transmitting the power control indicator over a communication channel.

31. The method of claim 30 wherein the step of transmitting comprises preparing the power control indicator for transmission over the communication channel by spreading the power control indicator with a spreading code prior to transmission over the communication channel.

32. The method of claim 30 wherein the communication channel is selected from the group consisting essentially of an electronic data bus, radio communication link, wireline and optical fiber link.

33. The method of claim 30 further comprising the steps of:

(a) detecting a power control indicator within a signal received from over the communication channel; and

(b) adjusting a particular signal transmission power of a signal transmitter in response to the detected power control indicator.

34. The method of claim 33 wherein the step of detecting comprises despreading the received signal with a spreading code to detect the power control indicator.