On the performance analysis of multiple access codes for ultra-wideband sensor networks

Ultra Wideband (UWB) technology is fast emerging as a potential contender for next generation wireless sensor networks because of the inherent low power requirements and built in security. Time hopping and direct sequence based spread spectrum techniques are employed for UWB multiple access systems, which makes the correlation properties of these techniques a critical issue in a multi-user (multiple nodes) scenario. In this paper we present a comparative performance analysis of different spreading codes namely, PN, Gold and Kasami using PPM and PAM modulation schemes over AWGN and IEEE 802.15.3a channel models. We use a PRake receiver for multipath channel. We observe that DS spreading technique is more suitable than TH for multi-user systems. Simulation results show that Kasami codes perform better than Gold and PN codes for all considered cases. However, Kasami codes can accommodate less number of nodes for a given code length due to their reduced set size. Thus, for small sensor networks Kasami codes should be deployed, where as for larger sensor networks Gold and PN codes are more suitable.