Adaptive blind multiuser equalizer based on PDF matching

In this paper, we propose a new adaptive technique for blind multiuser equalisation. The proposed approach is based on fitting the probability density function (pdf) of the equalizer output to the desired pdf of the corresponding symbol alphabet. The underlying pdf at the equalizer output is estimated by means of the Parzen Window method. A switch between blind and Decision Directed adaptation is possible by manipulating the kernal size of the Parzen Window Estimator. The cost function of the proposed technique can be measured by a stochastic gradient descent approach. The performance of the proposed adaptation strategy is assessed by a number of simulations, and benchmarked against Firmer-CMA under QPSK modulation.