RECEIVER FOR DIRECT-SEQUENCE SPREADING SPECTRUM ORTHOGONALLY-CODED SIGNAL USING THE 'RAKE' PRINCIPLE (COMPUTED DESIGN)

摘要

A method and apparatus for decoding an orthogonally encoded data signal in a noncoherent receiver system. The method is referred to as dual-maxima metric generation. It comprises the steps of sequentially searching for a maximum energy level in each of two subsets of a given set of symbol indexes and associated energy levels and calculating a difference of the two values to form a soft decision output value. The two subsets are identified by the binary value (either "0" or "1") of a given digit of the binary equivalent of the symbol index. The soft decision output value reflects a measure of confidence of the value of the corresponding digit of the original signal. The dual-maxima generator sequences through the steps one time for each binary digit of the original signal. The method allows the correlated energy from multiple receivers to be combined before the decoding of the signals, thus further reducing the complexity of the circuitry and improving the performance of the decoder.