Random sequence analysis of optimum near-far resistance in a variable chipping rate dual-rate CDMA system

Abstract

Direct-sequence code-division multiple-access (DS/CDMA) provides natural implementations for multi-rate communications systems. In this work, we will extend prior results on multi-rate systems with constant chipping rates to the case of variable chipping rate access (VCR) where chipping rates are proportional to user data rates. We use optimum near-far resistance as the performance measure of interest; thus for random sequences, the goal is to determine the average optimum near-far resistance. A random signature sequence analysis for the MMSE receiver operating in a single-rate system has been developed previously. We will combine the previous techniques; results on random matrices; and our prior work on variable spreading length (VSL) systems. The resulting two propositions for VCR systems are provided here.