Selective successive cancellation for decoding MIMO-OFDM transmission

A new iterative receiver based on Selective Successive Cancellation (SSC) is proposed for MIMO-OFDM systems. It improves the traditional successive cancellation (SC) method while having low complexity. The algorithm naturally interlaces the SC demodulation iterations with the decoding iterations. Error propagation is mitigated by making symbol decisions only when the confidence level defined from the decoded soft bit is high. The symbol decisions will be used in SC to improve the log-likelihood ratios (LLRs) of a subset of the transmitted bits. Special attention has been paid to the complexity of an iterative receiver in an effort to reduce both the number of demodulation iterations and the complexity of LLR update. The SSC scheme, with only two rounds of cancellation in one example, performs only 0.5 dB worse than the optimal soft joint detection (JD) receiver in a 4-Tx 4-Rx rate-1/2 turbo-coded MIMO OFDM system using QPSK at 4 b/subcarrier. With 16QAM at 8 b/subcarrier it outperforms the traditional MMSE receiver by over 1.5 dB.