Multipath division turbo equalization with block inter-carrier interference cancellation in cellular system with amplify-and-forward relaying

This paper proposes multipath division turbo equalization with block inter-carrier interference cancellation (MD-BIC) for orthogonal frequency division multiplexing (OFDM). When the multipath delay difference exceeds the cyclic prefix (CP) length, the OFDM transmission performance suffers severely due to inter-symbol interference (ISI) and inter-carrier interference (ICI). Cellular systems with amplify-and-forward (AF) relay stations, for example, might cause a long delay due to their process delays. Therefore, mobile terminals served by AF relay systems should compensate for the influence of ISI and ICI. MD-BIC divides a series of paths into several blocks by using a log likelihood ratio (LLR) that is computed in the decoding process. The delay difference within each block is limited so as not to exceed the CP length. This means that ISI and ICI are mitigated in each block. Computer simulations demonstrate that the proposed scheme can achieve excellent performance in the severe multipath channels where the delay difference is greater than the CP length.