LDPC Coded OFDM-IM Performance Evaluation under Jamming Attack

Orthogonal frequency division multiplexing (OFDM) with index modulation (OFDM-IM) that carries part of the incoming bits by active subcarrier indices is a recently proposed multicarrier modulation technique. OFDM-IM is considered as a promising candidate for 5G and beyond, due to its superiority over OFDM. In this paper, we show that uncoded OFDM-IM can achieve better error performance than uncoded OFDM in the presence of barrage jamming (BJ). Low-density parity-check (LDPC) coding is used to further improve the robustness of OFDM-IM system against jamming attacks. We investigate the optimum log-likelihood ratio (LLR) values of index bits and modulation bits under a jamming attack. We also show the superior performance of coded OFDM-IM, when compared to classical OFDM, at a high code rate in the presence of BJ. We propose a new model for partial band jamming (PBJ) that can attack each subcarrier with different power by adjusting the jamming coefficients. Simulation results show that OFDM-IM is more robust against PBJ than BJ.