Method and device for quantizing the input to soft decoders

• US 6,895,541 B1
• Filed: 01/28/2000
• Issued: 05/17/2005
• Est. Priority Date: 06/15/1998
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Yellin, Daniel
• Primary Examiner(s): CHUNG, PHUNG M
• Application Number:
  US09/493,004
• Time in Patent Office: 1,936 Days
• Field of Search: 714/746, 714/795, 714/759, 375/346, 375/262, 375/265, 375/341, 375/347, 375/348, 375/243, 370/302
• US Class Current: 714/746
• CPC Class Codes: H02J 7/0042 characterised by the mechanical construction
• CPC Class Codes: H02J 7/342 The other DC source being a battery actively interacting with the first one, i.e. battery to battery charging with circuits for polarity protection H02J7/0034
• CPC Class Codes: H04B 7/005 Control of transmission; Equalising
• CPC Class Codes: H04L 25/061 providing hard decisions only; arrangements for tracking or suppressing unwanted low frequency components, e.g. removal of dc offset removal of dc offset in coupling arrangements H04L25/029, H04L25/0296

Abstract

A receiver including a signal reception unit, for receiving a signal from a dynamically fading channel, a demodulator, connected to the signal reception unit, for demodulating the received signal, thereby producing a demodulated signal therefrom, a quantizing processor, connected to the demodulator and to the signal reception unit, for analyzing the received signal and for quantizing the demodulated signal, thereby producing a quantized signal, and a decoder, connected to the quantizing processor, for decoding the quantized signal, wherein the quantizing processor normalizes the demodulated signal according to the estimated fading of the received signal.

Claims

1. A method comprising:

detecting fading characteristics of a dynamically fading channel from a received signal; and

determining a set of correction parameters of a quantization correction command based on the fading characteristics for a segment of said received signal to be used to produce a quantized signal.

2. The method according to claim 1, further comprising quantizing at least a segment of the signal according to said quantization correction command, to produce the quantized signal.

3. The method according to claim 2, further comprising decoding said quantized signal.

4. The method according to claim 1, further comprising demodulating said received signal.

5. A method comprising:

detecting fading characteristics of a signal received over a dynamically fading channel by estimating a root-mean-square (RMS) of said received signal and computing the minimum and maximum quantities of samples of said received signal;

determining a set of correction parameters of a correction command according to the detected fading characteristic; and

quantizing at least one segment of said received signal according to said quantization correction command to produce a quantized signal.

6. The method according to claim 5, comprising:

estimating a desired root-mean-square value to determine the quantization correction command.

7. The method according to claim 6, further comprising normalizing said received signal according to said desired root-mean-square value.

8. The method according to claim 5, wherein detecting the fading characteristics comprises:

estimating a root-mean-square (RMS) of said received signal, to produce an Estimated_RMS value; and

estimating channel tap values ĥ

[n] from said received signal.

9. The method according to claim 8, wherein determining the quantization correction command comprises:

calculating Θ

_MIN and Θ

_MAX values, wherein Θ

[n]≡

|Real{ĥ

[n]}|+|Imag{ĥ

[n]}|, Θ

_MAX≡

Max_n {Θ

[n]}, and Θ

_MIN≡

Min_n{Θ

[n]}; and

determining a desired_RMS_fade value from said Θ

_MIN, Θ

_MAX, and Θ

[n].

10. The method according to claim 8, further comprising normalizing said received signal.

11. The method according to claim 10, wherein determining the quantization correction command comprises:

calculating Θ

_MIN and Θ

_MAX values, wherein Θ

[n]≡

|Real{ĥ

[n]}|+|Imag{ĥ

[n]}|, Θ

_MAX≡

Max_n {Θ

[n]}, and Θ

_MIN≡

Min_n{Θ

[n]}; and

determining a desired_RMS_fade value from said Θ

_MIN, Θ

_MAX, and Θ

[n]; and

wherein normalizing said samples is performed according to the following expression;

$\tilde{Y}<br><br>\left[n\right]=\frac{\mathrm{Desired\_RMS}<br><br>\mathrm{\_Fade}}{\mathrm{Estimated\_RMS}}·<br><br>Y<br><br>\left[n\right]$

wherein Y[n] denotes a pre-quantized value of a selected sample and {tilde over (Y)}[n] denotes a normalized pre quantized value of said selected sample.

12. The method according to claims 11, wherein said desired_RMS_fade value is determined from said Θ

_MIN, Θ

_MAX, Θ

[n] according to a look-up table having Θ

_MAX−

Θ

_MIN at its input and Desired_RMS_Fade at its output.

13. In a receiver which includes a signal reception unit, a demodulator and a decoder, the receiver receiving a signal from a dynamically fading channel, the demodulator demodulating said received signal to produce a demodulated signal, a quantizing device comprising:

a channel fading detection unit, coupled to said signal reception unit, to detect fading characteristics of said dynamically fading channel;

a processor, coupled to said channel fling detection unit, to process said fading characteristics so as to produce a quantization correction command that includes a set of correction parameters for at least one segment of said received signal; and

a quantizing unit, coupled to said processor, to said demodulator and to said decoder, to quantize said demodulated signal so as to produce a quantized signal and to correct said at least one segment according to said correction command, wherein said decoder is to decode said quantized signal.

14. In a receiver which includes a signal reception unit, a demodulator, a quantizing unit and a decoder, the receiver receiving a signal from a dynamically fading channel, the demodulator demodulating said received signal to produce demodulated signal, a fading compensation device comprising;

a channel fading detection unit, coupled to said signal reception unit, to detect fading characteristics of said dynamically fading channel;

a processor, coupled to said channel fading detection unit, to process said fading characteristics, so as to produce a correction command that includes a set of correction parameters to quantize at least one segment of said received signal; and

a correction unit, coupled to said processor, to said demodulator and to said quantizing unit, to correct a demodulated segment corresponding to said at least one segment according to said correction command so as to produce a corrected segment,

wherein said correction unit is to replace said demodulated segment with said corrected segment at the input of said quantizing unit.

15. The fading compensation device, according to claim 14, wherein said processor is further coupled to said decoder so as to provide said correction command to said decoder to enable decoding the quantized representation of said corrected segment, with respect to said correction command.

16. A receiver comprising:

a signal reception unit to receive a signal from a dynamically fading channel;

a demodulator, coupled to said signal reception unit, to demodulate said received signal to produce a demodulated signal therefrom;

a quantizing processor, coupled to said demodulator and to said signal reception unit, to analyze said received signal and to quantize said demodulated signal to produce a quantized signal; and

a decoder, coupled to said quantizing processor, to decode said quantized signal, wherein said quantizing processor is to normalize said demodulated signal according to the estimated fading of said received signal.

17. The receiver according to claim 16, wherein said received signal is a direct sequence—

code division multiple access (DS-CDMA) signal and wherein said demodulator is a rake receiver.

18. The receiver according to claim 17, wherein said quantizing processor is to analyze said received signal by summing channel taps of selected fingers.

19. The receiver according to claim 16, wherein said decoder is a Viterbi decoder.

20. A method of producing a quantized signal comprising:

quantizing at least one segment of a signal received over a dynamically fading channel by using a set of correction parameters of a quantization correction command that is determined, at least in part, from fading characteristics of said channel.

21. A receiver comprising:

a channel estimator to detect fading characteristics of a dynamically fading channel; and

a quantizer to quantize at least one segment of a signal received over said dynamically fading channel by using a set of correction parameters of a quantization correction command that is determined at least in part from said fading characteristics.

22. The receiver of claim 21 further comprising:

a processor coupled to said channel estimator and to said quantizer, said processor to produce said quantization correction command.

23. A receiver comprising:

a quantizer to quantize at least one segment of a received signal by using a set of correction parameters of a quantization correction command; and

a processor to determine said quantization correction command from code properties of a frame of said received signal containing said at least one segment,

wherein at least one frame of said received signal has different code properties than another frame of said received signal.

24. The receiver of claim 23, wherein said received signal received over a dynamically fading channel and said processor is further adapted to determined said quantization correction command from fading characteristics of said channel.