On the Mutual Information and Huffman Coding for OFDM-IM

As an improved multicarrier transmission technique of orthogonal frequency division multiplexing (OFDM), OFDM with index modulation (OFDM-IM) has attracted great attention for its flexible design of the transmission frame and better bit error rate (BER) performance compared with that of classical OFDM. In this paper, we investigate the optimal frequency-domain design of OFDM-IM to achieve the maximum capacity over frequency-selective Rayleigh fading channel. Unlike the conventional OFDM-IM with the same selected probability of each active indices combination (AIC), we select the AICs with different probabilities according the channel state information of the subcarriers. Based on the mutual information associated with each AIC, we propose a Huffman coding based adaptive OFDMIM to improve the BER performance. Simulations and numerical results demonstrate the proposed Huffman coding based OFDMIM achieves higher capacity and better BER performance.