Link capacity and signal power of CDMA systems according to spreading code and bandwidth allocations in multipath fading environments

Abstract

Reverse link performance analyses of single-code (SC) and multi-code (NIC) CDMA systems in multipath fading environments are presented. The degree of orthogonality loss among multiple spreading code channels is characterized by introducing the orthogonality factor. This factor depends on the multipath delay power profiles of the propagation channel and the number of paths resolved at a Rake receiver. The link capacity and the signal power of both CDMA systems are then analyzed according to varying system parameters, including spreading bandwidth, traffic load, the orthogonality factor, and the number of spreading codes assigned to a user. Analytical results show that the SC-CDMA system provides a larger link capacity and NIC users require more power than SC users. The dominant parameters affecting the performance difference are the spreading bandwidth and multipath delay power profiles.