Iterative PIC Detection and Channel Estimation for HAPS / Satellite DS-CDMA Systems

This paper presents a Turbo Multiuser Detector for Turbo-Coded DS-CDMA systems, based on the utilization of a PIC and a bank of turbo decoders, in which the PIC performs interference cancellation after each constituent decoder of the turbo decoding scheme. Moreover, the soft output of turbo decoders are used iteratively to improve the updating step of the channel parameter estimation which is formally equivalent to one step of the expectation-maximization algorithm. By means of computer simulations, we will show that the proposed receiver achieves performance comparable with systems which suppose perfect channel parameters knowledge for medium to high system loads, in AWGN channel. These results are obtained also in HAPS (High Altitude Platform Station) and satellite channel, for different values of the elevation angle.