Performance analysis of turbo coding with blind channel estimation based on subspace decomposition in a SIMO FIR channel

Abstract

This paper addresses the issue of blind channel estimation (BCE) of multi channel FIR filters. This is an issue arising in e.g. mobile communication systems using digital signaling. It also arises in the presence of frequency selective fading, when training (reference/pilot) symbols are unavailable. In this contribution we analyze the performances of ½ and - rate turbo codes of various frame lengths using BCE. The BCE technique used here is the second order statistics algorithm based on subspace decomposition (SSD). It has been shown in earlier work that the SSD algorithm, which exploits the orthogonality property between the noise subspace and the channel matrix, can estimate the channel's impulse response up to a multiplicative constant. The turbo coding schemes were combined with this BCE technique in order to characterize a realistic scenario. Two types of blind equalizers were investigated; the zero forcing and the minimum mean squared error equalizers.