Soft Information Aided Detection in Cooperative Spatial Multiplexing Systems

We investigate and evaluate the application of the soft information in the detection of cooperative spatial multiplexing (CSM) systems. The destination detects the signals transmitted from the relays with successive interference cancellation (SIC) whose performance suffers from the error propagation. The traditional detection methods assuming that the prior-detected symbols are correct, none of them considers the still existing error propagation. In this paper, we propose a novel soft-information-aided detection algorithm which takes advantage of the log-likelihood ratio (LLR) information of the prior-detected signals. In the proposed algorithm, the interference cancellation and detection ordering both take the error propagation effect into consideration, thus making the detection more reliable. The new algorithm will be performed in the ZF-SIC CSM systems, and the simulation results will show that the new proposed algorithm can achieve better BER performance compared with traditional ones.