Correlation Analysis for Spreading Codewords in Quasi-synchronous CDMA Communication

摘要

Spreading codes are designed to have good autocorrelation and crosscorrelation properties. Perfect synchronization is necessary to maintain the correlation properties to achieve the desired performance. But, due to imperfect synchronization in practical scenario, the correlation properties differ from the desired value. Individual codewords within a codeset behave differently due to difference in their autocorrelation and crosscorrelation properties. In this work, analysis of autocorrelation and crosscorrelation function is presented for fractional chip delays. Based on the analysis, a new performance metric is proposed to successfully rate the individual codewords in terms of their BER performance in quasi-synchronous scenario. Monte-Carlo simulation has been carried out to verify the analysis.