Adaptive MMSE receivers for communications in non-stationary multipath fading channel

This paper deals with two adaptive minimum mean square error (MMSE) receivers for direct sequence code division multiple access (DS/CDMA) wireless communication systems: in particular, the two different schemes, named postcombining and precombining are considered with two adaptive algorithms, the least mean squares (LMS) and the recursive least squares (RLS). The proposed adaptive MMSE receivers do not need knowledge of the desired user's signature waveform, only requiring the use of training sequences (TS) at start up, since a decision directed mode is adopted after the TS first transmission. The detectors performance is expressed in terms of the bit error rate (BER), which has been derived by simulations under the assumption of a frequency-selective Rayleigh fading channel. The reported simulation results shown highlight the adaptive MMSE receivers good behaviour and remarkable near-far resistance, even in worst fading environments.