Method and apparatus for power estimation in an orthogonal coded communication system

• US 5,297,161 A
• Filed: 06/29/1992
• Issued: 03/22/1994
• Est. Priority Date: 06/29/1992
• Status: Expired due to Term

• Current Assignee: Motorola Mobility, Inc. (Lenovo Group Ltd.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Ling, Fuyun
• Primary Examiner(s): Barron, Jr., Gilberto
• Application Number:
  US07/906,321
• Time in Patent Office: 631 Days
• Field of Search: 375/1, 324/76.33, 455/521, 455/52.2, 455/52.3, 455/69
• US Class Current: 375/130
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04J 13/004 Orthogonal
• CPC Class Codes: H04W 52/225 Calculation of statistics, e.g. average, variance
• CPC Class Codes: H04W 52/228 using past power values or information

Abstract

A method and apparatus is provided for estimating signal power. The estimating is accomplished by correlating (206) an input data vector (204) with a set of mutually orthogonal codes to generate a set of output values. The input data vector (204) consists of data samples of a received orthogonal coded signal (202). Each output value corresponds to a measure of confidence that the input data vector is substantially similar to one of the orthogonal codes from within the set of mutually orthogonal codes. Finally, an estimate of the power of the received orthogonal coded signal is generated (208) as a nonlinear function of the set output values.

Claims

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

(a) orthogonal code detector means for correlating an input data vector with a set of mutually orthogonal codes to generate a set of output values, the input data vector comprising data samples of a received orthogonal coded signal, each output value corresponding to a measure of confidence that the input data vector is substantially similar to one of the orthogonal codes from within the set of mutually orthogonal codes; and

(b) estimating means, operatively coupled to the orthogonal code detector means, for generating an estimate of the power of the received orthogonal coded signal as a nonlinear function of the set of output values.

2. The apparatus of claim 1 wherein the orthogonal code detector means generates the set of output values by utilizing a Hadamard transform matrix algorithm on the input data vector.

3. The apparatus of claim 1 wherein the estimating means comprises averaging means for averaging output values together from a plurality of sets of output values such that the signal power estimate is generated as a nonlinear function of the set of average output values.

4. The apparatus of claim 1 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 signal power estimate and a predetermined threshold.

5. The apparatus of claim 4 further comprising a signal transmitting means, operatively coupled to the threshold means, for transmitting the power control indicator over a communication channel.

6. The apparatus of claim 5 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.

7. The apparatus of claim 5 wherein the communication channel is selected from the group consisting essentially of an electronic data bus, radio communication link, wireline and optical fiber link.

8. The apparatus of claim 5 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.

9. The apparatus of claim 8 wherein the signal receiving means comprises means for despreading the received signal with a spreading code to detect the power control indicator.

10. The apparatus of claim 1 wherein:

(a) the signal power estimator orthogonal code detector means correlates the input data vector with a set of 64 mutually orthogonal codes to generate a set of 64 output values; and

(b) the signal power estimator estimating means generates the signal power estimate according to the following function;

##EQU12## where, n=a moment in time;

y_j (n)=a particular output value at time n;

y_i (n)=the largest output value at time n;

A_n² =signal power estimate at time n; and

f( )=a particular nonlinear function.

11. The apparatus of claim 10 wherein the signal power estimator estimating means comprises averaging means for averaging particular output values together from six sets of output values such that the signal power estimate is generated according to the following function:

##EQU13## where, A_n² =the long term average signal power estimate at time n.

12. The apparatus of claim 10 wherein the particular nonlinear function f( ) comprises:

##EQU14## such that the signal power estimator generates the signal power estimate according to the following function;

##EQU15##

13. The apparatus of claim 11 wherein the particular nonlinear function f( ) comprises:

##EQU16## such that the signal power estimator generates the signal power estimate according to the following function;

##EQU17##

14. A method of estimating signal power, comprising:

(a) correlating an input data vector with a set of mutually orthogonal codes to generate a set of output values, the input data vector comprising data samples of a received orthogonal coded signal, each output value corresponding to a measure of confidence that the input data vector is substantially similar to one of the orthogonal codes from within the set of mutually orthogonal codes; and

(b) generating an estimate of the power of the received orthogonal coded signal as a nonlinear function of the set of output values.

15. The method of claim 14 wherein the set of correlating comprises generating the set of output values by utilizing a Hadamard transform matrix algorithm on the input data vector.

16. The method of claim 14 further comprising a step of averaging output values together from a plurality of sets of output values such that the signal power estimate is generated as a nonlinear function of the set of average output values.

17. The method of claim 14 further comprising a step of setting a power control indicator in response to the result of a comparison between the signal power estimate and a predetermined threshold.

18. The method of claim 17 further comprising a step of transmitting the power control indicator over a communication channel.

19. The method of claim 18 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.

20. The method of claim 18 wherein the communication channel is selected from the group consisting essentially of an electronic data bus, radio communication link, wireline and optical fiber link.

21. The method of claim 18 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.

22. The method of claim 21 wherein the step of detecting comprises despreading the received signal with a spreading code to detect the power control indicator.

23. The method of claim 14 wherein:

(a) the input data vector is correlated with a set of 64 mutually orthogonal codes to generate a set of 64 output values; and

(b) the signal power estimate is generated according to the following function;

##EQU18## where, n=a moment in time;

y_j (n)=a particular output value at time n;

y_i (n)=the largest output value at time n;

A_n² =signal power estimate at time n; and

f( )=a particular nonlinear function.

24. The method of claim 23 the step of generating further comprises averaging particular output values together from six sets of output values such that the signal power estimate is generated according to the following function:

##EQU19## where, A_n² =the long term average signal power estimate at time n.

25. The method of claim 23 wherein the particular nonlinear function f( ) comprises:

##EQU20## such that the signal power estimate is generated according to the following function;

##EQU21##

26. The method of claim 24 wherein the particular nonlinear function f( ) comprises:

##EQU22## such that the signal power estimate is generated according to the following function;

##EQU23##