An adaptive antenna array based propagation delay estimation for DS-CDMA communication systems

This paper discusses the propagation delay estimation problem for DS-CDMA based on an adaptive antenna array which can suppress interfering signals. The tap weights of the adaptive beamformer are controlled by two adaptive algorithms such as direct matrix inversion (DMI) and linearly constrained minimum variance (LCMV). The large sample maximum likelihood (LSML) estimator is applied to the beamformer output data for estimating the propagation delay of a desired user in multi-user scenarios. The proposed approach is shown to provide better performance than that of a single antenna based LSML estimator via simulation results for 0 dB and 10 dB near-far ratio (NFR) situations. In addition, the Cramer-Rao bound (CRB) given M observation bits of received signals from multiple antenna sensors is derived for the parameter estimation problem.