Noncoherent MLSE in DS-CDMA wireless systems with antenna arrays

This paper addresses the noncoherent detection problem for direct-sequence code-division multiple-access (DS-CDMA) signals in the presence of antenna arrays at the base station. An ideal open-loop power control, which compensates for the long-term variations due to path loss and shadowing experienced by the mobile users, is assumed. Then, the noncoherent maximum-likelihood sequence-estimation problem is analyzed under the assumption of spatially white interference. The contribution of this paper is to extend previous results obtained by the author in for the case of multiantenna receivers, including the derivation and analysis of two suboptimal detectors based on an approximate maximization of the transmitted symbols likelihood. The first detector works as a traditional squared envelope combiner, which fully exploits the K diversity degrees provided by the multiple antenna system. In the second case, the receiver assumes a perfect knowledge of antenna response vector, so that spatial filtering of the received signal is made possible. Simulation and theoretical results are provided for a widely used circular ring of scatterers spatial channel model, which allows analysis in a wide range of different environmental conditions.