Turbo receiver with SC/ Simplified-MMSE(S-MMSE) type equalizer for MIMO channel signal transmission

摘要

MIMO channel transmission with turbo equalization is one of promising techniques to perform large capacity with limited bandwidth. Combinations of soft canceler and liner filter are proposed for the equalization parts, and matched filter(MF) or MMSE filter are used for the liner filter. The MF, however, does not have effects of intentional interference cancellation, thus causes FER performance degradation. On the other hand, the strict MMSE filtering needs symbol-by-symbol calculation of tap coefficients because of different degree of residual interference at each symbols. In this paper, we propose novel turbo equalization method for MIMO channel signal transmission. The proposed method utilized MMSE criterion to make tap coefficients based on the degrees of residual interference over a frame. The resultant tap coefficients are applied to all symbols on the frame. The proposed method achieves lower FER than those with MF, because our method also care for interference cancellation besides desired signal combining. Furthermore our method does not require much increase of computational complexity like symbol-by-symbol MMSE filter, as it applies common tap coefficient to all symbols over a frame. We show the effectiveness by link-level and system-level computer simulations and by complexity comparisons.