Iterative Interference Cancellation for STBC-OFDM System Over Doubly Selective Channel

The space time block coded orthogonal frequency division multiplexing (STBC-OFDM) system performance is severely degraded due to occurrence of co-channel interference (CCI) and inter-carrier interference (ICI) effects in mobile environment. In this work, three joint CCI and ICI iterative interference cancellation techniques are proposed namely diagonalized zero forcing detection (DZFD)-parallel interference cancellation (PIC)-DZFD, order iterative decision feedback (OIDF)-PIC-DZFD and OIDF-PIC-OIDF to obtain the transmitted signal over doubly selective channel. These proposed methods cancel the interferences in three stages. The CCI cancellation is performed to obtain initial data symbol in the initial stage followed by parallel-interference-cancelation (PIC). In the third stage, the ICI free signal is processed again by CCI cancellation method to obtain the refined estimated data symbols. Finally, the proposed and conventional methods are compared with respect to complexity and symbol error rate (SER). From the results, it is demonstrated that the proposed OIDF-PIC-OIDF method significantly outperforms the conventional methods with lower complexity.