Kaiman filter based non-isotropic channel estimation in space-time coded DS-CDMA systems

This paper deals with the estimation of rapidly time varying non isotropic Rayleigh fading channels in Space-Time (ST) coded direct sequence spread spectrum (DS-CDMA) systems. The effects of non isotropic scattering can be captured by using Von Mises distribution for the angle of arrival (AOA) of the scattered waves at the receiver. In order to benefit from the spatial diversity of ST coding, we need to have perfect channel information at the receiver. Kalman Filter (KF) with higher order autoregressive (AR) model is used for tracking and estimation of the non isotropic Rayleigh channel. The proposed algorithm outperforms the AR(1) based algorithms in tracking time varying channel especially under high Doppler spreads in directional scenarios. The effect of different Doppler rates and user loading on bit error rate (BER) performance of the proposed system are also studied.