Adaptive Noncoherent DS/CDMA Receivers with MDPSK Signals

The capacity of a direct-sequence code-division multiple-access (DS/CDMA) system is limited by multiple-access interference (MAI) and the near-far problem. Multiuser receivers provide solutions to these problems, but they require knowledge of parameters of the MAI and are computationally complex. Adaptive single-user receivers do not require knowledge of MAI parameters and need fewer computations. In this paper, we propose noncoherent receivers for M-ary differential phase-shift keying (MDPSK) signals. The performance of the proposed noncoherent receiver approaches that of a coherent MPSK receiver. The noncoherent receiver consists of a linear equalizer and a decision-feedback differential detector (DF-DD). The bit error rate (BER) performance comparisons of different proposed receivers are shown by the simulations.