The Influence of Initial-Phases of a PN Code Set on the Performance of an Asynchronous DS-CDMA System
The authors point out the need for fixed PN code sets for test purposes from the standpoint of numerical analysis and simulation of an asynchronous DS–CDMA system and its sub-system units. An agreement on test sequence sets and their initial phases for fixing the probability distribution function of the multiple-access interference (MAI) random variable is necessary in order to make the numerical performance results of different research groups and authors commensurable in large system design projects and in the CDMA literature. The conclusions are drawn from numerical examples of initial-phase optimization with the AO/LSE, LSE/AO, MSE/AO, CO/MSQCC and MSQCC/CO criteria, and by reviewing the literature. Optimization criteria are compared from the standpoint of minimum MAI. Conclusions are drawn from their order of quality and the conditions under which the optimization is practicable. Finally, some binary and quadri-phase PN code sets for fixing the MAI signal component for test purposes are reviewed.