Granted Patent B2

US 8,077,816 · App. 11/849,551 · Granted Dec 13, 2011

Abstract

Claims (77)

1. A method of fast predictive automatic gain control, comprising:

estimating channel gain applied to a received signal;

predicting channel gain at a subsequent time by applying temporal correlation statistics to the estimated channel gain;

predicting error variance at the subsequent time by applying the temporal correlation statistics to the estimated channel gain;

determining a predicted receiver gain which reduces variance between the predicted channel gain and a predetermined target power level, wherein said determining a predicted receiver gain comprises combining the predicted channel gain and the predicted error variance; and

applying the predicted receiver gain to the received signal.

2. The method of claim 1 , wherein said predicting channel gain comprises applying linear minimum mean-squared error (LMMSE) prediction to the estimated channel gain.

3. The method of claim 1 , wherein:

said estimating channel gain comprises estimating channel gain of pilot symbols within the received signal; and

wherein said predicting channel gain comprises:

estimating a temporal correlation function using the estimated channel gain of the pilot symbols; and

determining predicted channel gain using the estimated channel gain of the pilot symbols and the estimated temporal correlation function.

4. The method of claim 3 , wherein:

said estimating a temporal correlation function comprises:

using estimated channel gain values of the pilot symbols to determine temporal autocorrelation values; and

interpolating between the temporal autocorrelation values to determine temporal cross-correlation values; and

wherein said determining predicted channel gain comprises:

determining predictor coefficients using the temporal autocorrelation values and the temporal cross-correlation values; and

linearly combining the estimated channel gain values of the pilot symbols and the predictor coefficients to determine predicted channel gain values.

5. The method of claim 4 , further comprising:

combining the temporal autocorrelation values and the temporal cross-correlation values to determine corresponding predicted error variance values; and

wherein said determining a predicted receiver gain comprises combining the predicted channel gain values and the predicted error variance values to determine corresponding predicted receiver gain values.

6. The method of claim 5 , further comprising:

sampling the received signal to provide signal samples;

down sampling the signal samples at pilot locations to provide pilot symbol samples;

storing the predicted receiver gain values to provide current gain values;

down sampling the current gain values at the pilot locations to provide pilot gain values; and

said estimating channel gain of the pilot symbols comprising combining the pilot symbol samples, the pilot gain values, and known pilot symbols.

7. The method of claim 6 , further comprising:

converting the current gain values to a gain signal; and

wherein said applying the predicted receiver gain to the received signal comprises amplifying the received signal by the gain signal.

8. A channel estimation and gain prediction system for a receiver for fast predictive automatic gain control, comprising:

a channel gain estimator which estimates channel gain applied to a received signal and which determines an estimated channel gain;

a channel gain predictor which predicts channel gain at a subsequent time by applying temporal autocorrelation statistics to said estimated channel gain to provide a predicted channel gain, and wherein said channel gain predictor determines a predicted error variance;

a predictive gain controller which uses said predicted channel gain and said predicted error variance to determine a predicted receiver gain to reduce variance between said predicted channel gain and a target power level; and

a gain circuit which applies said predicted receiver gain to said received signal.

9. The channel estimation and gain prediction system of claim 8 , wherein said channel gain estimator determines a least-squares estimate of the channel gain of known pilot symbols within said received signal.

10. The channel estimation and gain prediction system of claim 8 , wherein said channel gain predictor applies linear minimum mean-squared error (LMMSE) prediction to said estimated channel gain to determine said predicted channel gain.

11. The channel estimation and gain prediction system of claim 8 , further comprising:

a variable resolution analog to digital converter (ADC) having a first input receiving said received signal, a second input receiving a resolution control signal, and an output providing received signal samples; and

a dynamic range determination circuit having an input receiving said received signal samples and an output providing said resolution control signal;

wherein said dynamic range determination circuit controls said resolution control signal to reduce resolution of said variable resolution ADC based on dynamic range of said received signal samples.

12. The channel estimation and gain prediction system of claim 8 , further comprising:

said predictive gain controller having an output providing predicted receiver gain values;

a memory device having an input receiving said predicted receiver gain values and an output providing current receiver gain values;

a digital to analog converter having an input receiving said current receiver gain values and an output providing a gain signal; and

wherein said gain circuit has a first input receiving said received signal, a second input receiving said gain signal, and an output providing a gain-controlled received signal.

13. The channel estimation and gain prediction system of claim 8 , further comprising:

said received signal comprising known periodic symbols;

an analog to digital converter (ADC) having an input receiving said received signal and an output providing received signal samples;

a memory device having an input receiving said predicted receiver gain and an output providing current receiver gain values;

wherein said channel gain estimator has a first input receiving said received signal samples, a second input receiving said current receiver gain values, and an output providing estimated channel gain values based on said known periodic symbols, said received signal samples at periodic symbol locations, and said current receiver gain values corresponding to said periodic symbol locations.

14. A channel estimation and gain prediction system for a receiver for fast predictive automatic gain control, comprising:

a channel gain estimator which estimates channel gain applied to a received signal and which determines an estimated channel gain;

a channel gain predictor which predicts channel gain at a subsequent time by applying temporal autocorrelation statistics to said estimated channel gain to provide a predicted channel gain;

a predictive gain controller which uses said predicted channel gain to determine a predicted receiver gain to reduce variance between said predicted channel gain and a target power level;

a gain circuit which applies said predicted receiver gain to said received signal;

a channel statistics estimator having an input receiving said estimated channel gain and an output providing temporal correlation values; and

wherein said channel gain predictor has a first input receiving said estimated channel gain, a second input receiving said temporal correlation values, and a first output providing predicted channel gain values based on said estimated channel gain and said temporal correlation values.

15. The channel estimation and gain prediction system of claim 14 , wherein said channel gain predictor has a second output providing predicted error variance values.

16. The channel estimation and gain prediction system of claim 15 , wherein said predictive gain controller has a first input receiving said predicted channel gain values, a second input receiving said predicted error variance values, and an output providing predicted receiver gain values.

17. A receiver, comprising:

a radio which receives and converts a transmitted signal into a received signal and which amplifies said received signal by a predictive gain signal to provide a gain-controlled received signal;

an analog to digital converter (ADC) having an input receiving said gain-controlled received signal and an output providing received signal samples;

a channel estimation and gain prediction circuit, comprising:

a channel predictor having a first input receiving said received signal samples, a second input receiving current gain values, a first output providing predictive channel gain values and a second output providing predictive error variance values, wherein said predictive channel gain values and said predictive error variance values are determined using a temporal correlation function;

a predictive gain controller having a first input receiving said predictive channel gain values, a second input receiving said predictive error variance values, and an output providing predictive gain values; and

a memory device having an input receiving said predictive gain values and an output providing said current gain values; and

a digital to analog converter (DAC) having an input receiving said current gain values and an output providing said predictive gain signal.

18. The receiver of claim 17 , further comprising:

said ADC comprising a variable resolution ADC having a resolution adjust input; and

a dynamic range determination circuit having an input receiving said received signal samples and an output providing a resolution control signal to said adjust input of said variable resolution ADC;

wherein said dynamic range determination circuit controls said resolution control signal to reduce resolution of said variable resolution ADC based on dynamic range of said received signal samples.

19. The receiver of claim 17 , wherein said channel predictor comprises:

a channel gain estimator having a first input receiving said received signal samples, a second input receiving said current gain values, a third input receiving known pilot symbols, and an output providing channel gain estimate values;

a channel statistics estimator having an input receiving said channel gain estimate values and an output providing temporal correlation values; and

a channel gain predictor having a first input receiving said channel gain estimate values, a second input receiving said temporal correlation values, a first output providing said predictive channel gain values and a second output providing said predictive error variance values.

Assignments (31)