Rake combining methods and apparatus using weighting factors derived from knowledge of spreading spectrum signal characteristics

A method of recovering information encoded in a first spread spectrum signal transmitted according to a first spreading sequence in a communications medium, the method comprising the steps of:

• iteratively generating weighting factors from an estimated channel response, an estimated impairment correlation, and previously determined weighting factors;
• receiving a composite signal including the first spread spectrum signal from the communications medium;
• correlating the composite signal with the first spreading sequence to produce a plurality of time-offset correlations of the composite signal with the first spreading sequence;
• and
• combining the correlations according to the iteratively generated weighting factors to estimate information encoded in the transmitted first spread spectrum signal.

An apparatus for recovering information encoded in a first spread spectrum signal transmitted according to a first spreading sequence in a communications medium, the apparatus comprising:

• means for receiving a composite signal including the first spread spectrum signal from the communications medium;
• means, responsive to said means for receiving, for correlating the composite signal with the first spreading sequence to produce a plurality of time-offset correlations of the composite signal with the first spreading sequence;
• means for generating weighting factors based on knowledge of spread spectrum signals in the composite signal, including pulse shaping information;
• and
• means, responsive to said means for correlating and to said means for generating weighting factors, for combining the correlations according to the weighting factors to estimate information encoded in the transmitted first spread spectrum signal.

An apparatus for recovering information encoded in a first spread spectrum signal transmitted according to a first spreading sequence in a communications medium, the apparatus comprising:

• means for iteratively generating weighting factors from an estimated channel response, an estimated impairment correlation, and previously determined weighting factors;
• means for receiving a composite signal including the first spread spectrum signal from the communications medium;
• means, responsive to said means for receiving, for correlating the composite signal with the first spreading sequence to produce a plurality of time-offset correlations of the composite signal with the first spreading sequence;
• and
• means, responsive to said means for iteratively generating weighting factors and to said means for correlating, for combining the correlations according to the iteratively generated weighting factors to estimate information encoded in the transmitted first spread spectrum signal.

An apparatus for recovering information encoded in a first spread spectrum signal transmitted according to a first spreading sequence in a communications medium from a composite signal received from the communications medium, the apparatus comprising:

• a correlation unit operative to correlate the composite signal with the first spreading sequence to produce a plurality of time-offset correlations of the composite signal with the first spreading sequence;
• a weighting factor generator operative to generate weighting factors based on knowledge of spread spectrum signals in the composite signal, including pulse shaping information;
• a weighted combiner responsive to said correlation unit and to said weighting factor generator and operative to combine the correlations according to the weighting factors to produce a decision statistic;
• and
• a detector responsive to said weighted combiner and operative to generate an estimate of information encoded in the transmitted first spread spectrum signal from the decision statistic.

An apparatus for recovering information encoded in a first spread spectrum signal transmitted according to a first spreading sequence in a communications medium from a composite signal received from the communications medium, the apparatus comprising:

• a weighting factor generator operative to iteratively generate weighting factors from an estimated channel response, an estimated impairment correlation, and previously determined weighting factors;
• a correlation unit operative to correlate the composite signal with the first spreading sequence to produce a plurality of time-offset correlations of the composite signal with the first spreading sequence;
• a weighted combiner responsive to said correlation unit and to said weighting factor generator to combine the correlations according to weighting factors produced by the weighting factor determiner to produce a decision statistic;
• and
• a detector responsive to said weighted combiner to generate an estimate of information encoded in the transmitted first spread spectrum signal from the decision statistic.