Optimum PSK signal constellation for Multi-Phase B-CDMA Systems

Abstract

Although CDMA system can efficiently support multiple users, it suffers from large peak-to-average power ratio (PAPR) as the number of users increases. It requires the use of a highly linear power amplifiers with a large back off. Recently, a new CDMA scheme, called binary CDMA (B-CDMA), has been proposed to alleviate this problem [1]. In B-CDMA systems, the envelope of multi-user CDMA signals is truncated into a small number of levels to reduce the PAPR. The performance of B-CDMA system is mainly limited by two types of noise; the truncation and decision error. The truncation noise can be minimized by Lloyd-max algorithm [2]. In this paper, the optimum PSK signal constellation is analytically designed in multi-phase B-CDMA to minimize the decision errors. Finally, the analytic results are verified by computer simulation.