Advanced ICA-based receivers for DS-CDMA systems

Abstract

We consider blind interference suppression in direct-sequence code division multiple access (DS-CDMA) communication system, and the means of a statistical technique called independent component analysis (ICA) are taken as a solution for the problem. ICA for complex valued signals has received special attention lately due to its applicability to many practical problems. We consider complex ICA especially via the known FastICA algorithm. A drawback of many ICA algorithms, including FastICA, in CDMA is that all the available a-prior information is not necessarily utilized. We propose a solution for this problem by considering ICA as a tuning element, which is attached to an existing receiver structure. Two types of receiver structures, RAKE-ICA and MMSE-ICA, are studied in a block fading CDMA downlink. Numerical studies indicate that the performance of the RAKE and subspace MMSE detector, respectively, can be greatly improved. This is mainly due to the fact that ICA is able to utilize also the independence of the original signals, and that ICA does not explicitly depend on the erroneous timing or channel estimation.