A Novel Pairing Diversity Technique with Dynamic Code Allocation for CDMA Systems Employing Polyphase Sequences

Abstract

This paper introduces and analyses a novel uplink CDMA pairing diversity technique. In particular, this paper considers the use of orthogonal polyphase (OPP) sequences on the synchronous and asynchronous uplink to benefit from the codes' good cross-correlation properties. A code allocation algorithm is also presented in this paper that aims to exploit the cross-correlation properties to achieve the best possible system performance. For the sake of comprehensiveness, the paper compares the performance of this new diversity technique with a conventional pairing diversity technique and with the well known maximum gain combined (MGC) time diversity. The results show that the proposed algorithm outperforms the conventional pairing technique, in terms of BER, and with proper code allocation, is also able to outperform time diversity systems. The new algorithm is able to accommodate up to 200% system loading even under severe asynchronous and multipath conditions.