A fast blind multiple access interference reduction in DS/CDMA systems by adaptive projected subgradient method

This paper presents a novel blind multiple access interference (MAI) suppression filter in DS/CDMA systems. The filter is adaptively updated by parallelly projecting them onto a series of convex sets. These sets are defined based on the received signal as well as a priori knowledge about the desired user´s signature. In order to achieve fast convergence and good performance at steady state, the adaptive projected subgradient method (Yamada et al., 2003) is applied. The proposed scheme also jointly estimates the desired signal amplitude and the filter coefficients based on a stochastic approximation of an EM type algorithm, following the original idea proposed by Park and Doherty, 1997. Simulation results highlight the fast convergence behavior and good performance at steady state of the proposed scheme.