US 2002/0057731 A1Published application

Matched-filter obtained side information for relative-signal-level data detection from a spread-spectrum signal

AssigneeLinex Technologies, Inc.

InventorDonald L. Schilling

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Abstract

An improvement to a spread-spectrum base station receiver having a matched filter. A symbol sampler samples at the symbol time TS, a plurality of symbol samples from the matched filter. A relative-signal-level decoder decodes the plurality of received-symbol samples, thereby generating a plurality of decoded-symbol samples. 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, before, after, or a combination of before and after, a symbol sample. An estimator processes the plurality of noise samples. The erasure detector detects for each decoded-symbol sample from the plurality of decoded-symbol samples and from the plurality of noise samples, an erasure condition for the corresponding decoded-symbol sample, and thereby generates an erasure signal. An erasure decoder erasure decodes the input data using the erasure signals from the erasure detector.

Claims7

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 modulating differentially-encoded symbols, 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 a matched filter having an impulse response matched to a desired chip-sequence signal in the plurality of chip-sequence signals, 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 relative-signal-level decoder, coupled to said symbol sampler, for relative-signal-level decoding the plurality of symbol samples, thereby generating a plurality of decoded-symbol samples;
a noise sampler, coupled to said matched filter, for sampling at any of before, after, or a combination of before and after each decoded-symbol sample, at a plurality of chip times kTC, but not at the plurality of symbol times nTS, a plurality of noise samples;
an estimator, coupled to said noise sampler, for processing the plurality of noise samples to generate a noise estimate;
an erasure detector, coupled to said estimator and to said symbol sampler, for detecting from a particular symbol sample corresponding in time to the particular decoded-symbol sample and the noise estimate, an erasure condition, thereby generating an erasure signal;
and
an erasure decoder, having an erasure input coupled to said erasure detector and a data input coupled to said relative-signal-level decoder, responsive to the erasure signal, for erasure decoding the data input.

4 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 modulating differentially-encoded data, 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, a plurality of symbol samples;
relative-signal-level means, coupled to said sampler means, for relative-signal-level decoding the plurality of symbol samples, thereby generating a plurality of decoded-symbol samples;
said sampler means for sampling at any of before, after, or a combination of before and after each symbol sample corresponding to the particular decoded-symbol sample from a plurality of decoded-symbol samples, at a plurality of chip times kTC, but not at the plurality of symbol times nTS, a plurality of noise samples;
estimate means, coupled to said sampler means, for processing the plurality of noise samples to generate a corresponding noise estimate for each decoded-symbol sample;
erasure-detection means, coupled to said estimate means, for detecting from the corresponding noise estimate and a symbol sample corresponding to each decoded-symbol sample from the plurality of decoded-symbol samples, an erasure condition, thereby generating a corresponding erasure signal;
and
an erasure decoder, having an erasure input coupled to said erasure-detection means and a data input coupled to said relative-signal-level means, responsive to the erasure signal, for erasure decoding the plurality of decoded-symbol samples.

4 more elements

Dependencies are inferred from the claim text.