Fading rate and multipath delay effects on signal acquisition using sliding correlation in a multi-user environment

Abstract

The ability of spread spectrum systems to combat interference can only be realised if the receiver is precisely synchronised with the incoming signal. The use of the sliding correlator for the acquisition of direct sequence spread spectrum signals is a popular method. Previous work considered either the single user in the fading and delay mobile environment or multi-users in the additive white Gaussian noise environment. In this paper the acquisition performance of the sliding correlator for direct sequence spread spectrum signals is investigated for the uplink case and in an environment where interference is caused both by multiple users and by multipath delays with different fading rates. The results show that a longer correlator length is required for optimum mean acquisition time in a slow fading environment. However in the multi-user, multipath environment when larger delays are present, the use of a longer correlation length is necessary in order to optimise the mean acquisition time.