改善误码性能的索引调制正交频分复用混合映射方案

A hybrid mapping scheme is proposed in this paper to improve further the Bit Error Rate (BER) performance of Orthogonal Frequency Division Multiplexing with Index Modulation (OFDM-IM) system for high Signal-to-Noise Ratio (SNR). By taking advantage of the fact that the BER of index bits is lower than that of data bits in the high SNR region, the scheme uses two allocation strategies of index bits with different numbers, which increases the proportion of index bits. Correspondingly, the Subcarrier Activation Patterns (SAPs) are divided into super SAPs and normal SAPs. Compared with normal SAPs, super SAPs have seen increased index bits and decreased data bits by 1 bit respectively. The decreased data bits corresponding to a super SAP are supplemented with a parity-check bit and then mapped into symbols, which improves the diversity order of OFDM-IM system and increases the minimum Euclidean distance between symbols. The simulation results show that, compared with the previous mapping scheme, the hybrid mapping scheme can gain about 1～3 dB when BER is 10^–4, and improve effectively the BER performance of OFDM-IM system.