Adaptive receivers with PN code tracking for DS-CDMA communications

In this paper, the novel adaptive single-user receivers with PN code tracking for direct sequence code division multiple access (DS-CDMA) in multipath environment are proposed. The coherent receiver estimate the desired signal and code delay to achieve code synchronization by least mean square (LMS) algorithm simultaneously. For noncoherent detection, we combine the decision-feedback differential detection with the coherent receiver to deal with the noncoherent MDPSK signals. In these two proposed schemes, an "error signal" is used to update the adaptive tap weights and the estimated code delay. Increase the number of feedback symbols can improve the performance of noncoherent receiver. Simulations confirm the good performance, including BER and timing tracking, of the proposed coherent and noncoherent receivers