Code-hopping as a new strategy to improve performance of S-CDMA cellular systems
B. Sayrac Unal, T. Tamk · 2002
An alternative coding strategy to the fixed spreading code assignment of code-division multiple-access (CDMA) systems, called code-hopping is proposed for the uplink path of synchronous CDMA (S-CDMA) systems. In code-hopping S-CDMA, mobile users swap their spreading codes according to a predetermined hopping pattern. In this way, mobile channels which are identified by the spreading codes are exchanged. Performance of code-hopping on the uplink path of S-CDMA systems is evaluated numerically on a typical S-CDMA system in the case of random hopping and compared to that of conventional S-CDMA. In performance evaluation, the criterion is the uplink outage probability which is defined as the probability of the uplink interference power exceeding a predetermined threshold. The numerical results show that application of code-hopping to the uplink communication of S-CDMA systems decreases the outage probability significantly.