Adaptive filtering based DS/SS code acquisition in frequency selective and flat Rayleigh fading channels

The mean acquisition time performance for a code acquisition scheme utilizing an FIR adaptive filter is investigated. Both frequency selective and frequency nonselective Rayleigh fading channels are considered. It is shown that fading causes a performance degradation of less than 3 dB for both the coherent and noncoherent cases when the carrier phase is varying slowly, and less than 5 dB for the noncoherent case with fast phase variations. This degradation is significantly smaller than that suffered by other systems based on using matched filters (about 10-15 dB degradation).