US 6,714,583 B2 · Matched-filter obtained side information for spread-spectrum data detection

Abstract

An improvement to a spread-spectrum receiver having a matched filter. A symbol sampler samples at the symbol time TS, a symbol sample from the matched filter. A noise sampler samples at a plurality of chip times kTC, but not at the symbol time TS, a plurality of noise samples from the matched filter. An estimator or low-pass filter estimates the plurality of noise samples from the symbol sampler, to generate a noise estimate. A combiner subtracts the noise estimate from the symbol sample, thereby generating a comparison signal. A magnitude device determines a magnitude of the comparison signal. A comparator compares the magnitude of the comparison signal to the threshold voltage, thereby generating the erasure signal. An erasure decoder erasure decodes the input data using the erasure signals from the erasure detector.

Claims16

Dependent claims

An improvement to a spread-spectrum receiver at a base station in a direct-sequence code-division-multiple-access (DS-CDMA) system having a plurality of spread-spectrum signals with each spread-spectrum signal in the plurality of spread-spectrum signals having a chip-sequence signal lasting a symbol time TS, and with each chip-sequence signal different from other chip-sequence signals used by other spread-spectrum signals in the plurality of spread-spectrum signals, with the spread-spectrum receiver including despreading means for detecting a desired spread-spectrum signal in the plurality of spread-spectrum signals arriving at the spread-spectrum receiver, the improvement comprising:

a symbol sampler, coupled to said matched filter, for sampling at a plurality of symbol times nTS, where n is an index to each symbol time, a plurality of symbol samples;
a noise sampler, coupled to said matched filter, for sampling a plurality of noise samples at any of before, after, and a combination of before and after each symbol sample;
a low-pass filter, coupled to said noise sampler, for filtering the plurality of noise samples, to generate a noise estimate corresponding to a particular symbol sample in the plurality of symbol samples;
a combiner circuit, coupled to said low-pass filter and to said symbol sampler, for subtracting the noise estimate from the particular symbol sample, thereby generating a comparison signal;
a magnitude device, coupled to said combiner circuit, for determining a magnitude of the comparison signal;
and
a comparator, coupled to said magnitude device and having a threshold voltage applied to a threshold input, for comparing the magnitude of the comparison signal to the threshold voltage, thereby generating the erasure signal;
and
an erasure decoder, having an erasure input coupled to said comparator and a data input coupled to said symbol sampler, responsive to the erasure signal for erasure decoding the symbol sample.

6 more elements

An improvement to a spread-spectrum receiver in a direct-sequence code-division-multiple-access (DS-CDMA) system having a plurality of spread-spectrum signals with each spread-spectrum signal in the plurality of spread-spectrum signals having a chip-sequence signal lasting a symbol time TS, and with each chip-sequence signal different from other chip-sequence signals used by other spread-spectrum signals in the plurality of spread-spectrum signals, with the spread-spectrum receiver including despreading means for detecting a desired spread-spectrum signal in the plurality of spread-spectrum signals arriving at the spread-spectrum receiver, the improvement comprising:

sampler means, coupled to said matched filter, for sampling at a plurality of symbol times nTS, where n is an index of each symbol time, a plurality of symbol samples;
said sampler means for sampling at any of before, after, or a combination of before and after each symbol sample from a plurality of symbol samples, a plurality of noise samples;
estimate means, coupled to said sampler means, for processing, from the plurality of noise samples, a noise estimate corresponding to the particular symbol sample;
comparator means, coupled to said estimate means, for comparing the noise estimate with the particular symbol sample, to generate an erasure signal;
and
an erasure decoder, having an erasure input and a data input, with the erasure input coupled to the said comparator means, and with the data input coupled to said sampler means, for erasure decoding the symbol sample using the erasure signal.

3 more elements

A method for improving a spread-spectrum receiver in a direct-sequence code-division-multiple-access (DS-CDMA) system having a plurality of spread-spectrum signals with each spread-spectrum signal in the plurality of spread-spectrum signals having a chip-sequence signal lasting a symbol time TS, and with each chip-sequence signal different from other chip-sequence signals used by other spread-spectrum signals in the plurality of spread-spectrum signals, with the spread-spectrum receiver including despreading means for detecting a desired spread-spectrum signal in the plurality of spread-spectrum signals arriving at the spread-spectrum receiver, the improvement comprising the steps of:

sampling at a plurality of symbol times nTS, where n is an index of each symbol time, a plurality of symbol samples;
sampling, for each symbol sample, a plurality of noise samples;
estimating, from the plurality of noise samples corresponding to a particular symbol sample, a noise estimate;
comparing the noise estimate with the symbol sample, to generate an erasure signal;
and
erasure decoding the symbol sample using the erasure signal.

3 more elements

Dependencies are inferred from the claim text.

Matched-filter obtained side information for spread-spectrum data detection

Life of this patent

Matched-filter obtained side information for spread-spectrum data detection

Life of this patent

Abstract

Claims16