Optimal Codes and Filters for Hard-Limited OQPSK/DS Multiple Access Systems

Abstract

The worst case detectability is optimized with respect to the combined choice of the Spread Spectrum (SS) codes and receiver filters in a hard limited multi-access system. The multi-access repeater with a hard limiter will provide access to a group of n SS users, each employing pseudorandom (i.e. direct sequence DS) codes in the inphase (I) and quadrature (Q) channels of the offset Quadrature Phase Shift Keying OQPSK/DS system. Both like user interference and AWGN will be considered. Maximal linear codes, Gold, and Kassami codes of different lengths and raised cosine, Gaussian, Butterworth and Chebyshev band-pass filters of different shapes will form the set of the maximizing parameters.