Comparison of the performance of some linear spreading code families for asynchronous DS/SSMA systems

The performance of an asynchronous biphase coded direct sequence spread-spectrum multiple-access (DS/SSMA) system is studied, when maximum length, Gold, and a small set of Kasami sequences are used as spreading codes. The signal-to-noise ratio (SNR) at the output of an asynchronous DS/SSMA receiver and the average interference parameter were used as performance measures. It was found that use of the AO/LSE and LSE/AO phase optimization criteria did not give any significant advantage in decibels as compared to randomly selected sequence phases, as the criteria do not minimize cross-correlation functions directly. There are no appreciable differences in SNR performance between sets of Gold, Kasami, and M-sequences. The SNR performance curves of sets of Gold, Kasami, and M-sequences of sufficiently long periods were found to be very close to those of sufficiently random, independent binary spreading sequences of equal length