Second order moment estimation for multilevel quantized tailed shifts sequences optimising BER for asynchronous DS-CDMA systems

摘要

Chaotic sequences offer a good alternative for spreading in DS-CDMA (direct sequence-code division multiple access) systems. These sequences are generated by nonlinear feedback dynamical systems and have interesting features like a very sensitive dependency on the initial state and noiselike correlation properties. This paper considers the case of a very well known family of PWAM (piece-wise affine Markov) maps, namely (n,t)-tailed shifts maps, and their quantized versions. In DS-CDMA systems the MAI (multiple access interference) is depending on the correlation properties of the spreading sequences. Hence, here we present the estimation method for the second order statistical moment of quantized (n,t)-tailed shifts sequences and its optimization for reducing MAI.