DS-CDMA SYSTEMS USING Q-LEVEL M-SEQUENCE - CODING MAP THEORY

GF(q) m sequences with complex spreading mapping are considered for DS -CDMA systems by referring to three different environments with increa sing synchronicity levels. For all environments, performance evaluatio n is derived both with a deterministic approach requiring spreading se quence specification, and with a statistical derivation, based on the assumption of spreading sequence ergodicity, in order to give closed-f orm performance theory. The optimal mapping design criterion, through zero-mean complex code mapping, is computed for all environments and v alidated through several numerical tests. Performance invariance, with respect to sequence levels, has been demonstrated for low synchronous environments, where the proposed sequence gives better performance.