A simplified model for probability of error in DS CDMA systems with adaptive antenna arrays

The multi-access interference and the array gain has been modelled to evaluate the average probability of error in DS-CDMA receivers with adaptive antenna arrays. The angular gain of the spatial filter (array beam pattern) is modelled by a piece-line function that approximates the pass-band (or in-beam) with a fixed beamwidth and the stop-band (or out-beam) with an equivalent attenuation. The interferers are partitioned into in-beam and out-beam users and are counted differently for the evaluation of the probability of error. The in-beam users are counted as interference while the out-beam users increase the additive Gaussian noise level. This simple model adapted to 2D RAKE receiver structures and to space-time multiuser detection shows good agreements with simulation results