A Simple Multiuser Detector for DS/CDMA Systems

摘要

A new CDMA multiuser detector is proposed which provides near-optimum bit detection and simultaneous tracking of delays and amplitudes of system users. The detector incorporates an extended multiuser early-late tracking algorithm for delay tracking, and an adaptvie DFE for bit detection and complex amplitude estimation. This receiver is developed under the assumption that the amplitudes and phases of all users are unknown a prior, and the delays are estimated to within half a chip. With the near-optimum DFE multiuser detection structure, it is capable of rejecting multiuser interference and thus is not near-far limited. It is shown that the complexity of this receiver is considerably reduced compared to previously studied CDMA joint detection/estimation receivers [3]. Computer simulation results are presented which illustrate that the algorithm successfully estimates the delays and amplitudes, and the bit detection error is comparable to the DFE with perfect knowledge of parameters, given suitable initialization of the delay estimates.