A Near Optimum Low Complexity Detection Algorithm for MIMO OFDM Channels

In this paper, a joint detection algorithm is proposed for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) channels. In MIMO OFDM channels, if enough cyclic prefix (CP) is used, intersymbol interference is completely cancelled and consequently spatial multiplexing interference (SMI) is the main limiting factor in performance. The proposed algorithm is based on a new soft parallel interference cancellation (SPIC) technique where, in each iteration, a part of SMI proportional to the probability of correctness of estimation in last iteration is cancelled. This probability is calculated approximately assuming the correct estimation for other sub-streams in last iteration. The proposed algorithm approaches the optimum performance in only a few iterations. The proposed algorithm is simulated for 4 states 1/2 turbo code and 8times12, 12times12 and 4times4 MIMO OFDM channels for different values of the E_b/N₀. Bit error rate (BER) and frame error rate (FER) are considered as comparison criteria and it is shown that its performance is good and very close to interference free (lower bound) case.