Orthogonal Frequency Division Multiplexing With Joint Subblocks Index Modulation

Recently, orthogonal frequency division multiplexing (OFDM) with index modulation has emerged as promising technologies with the improvement of spectral efficiency and energy efficiency, which carries additional index bits through the index domain. In OFDM-IM, some indices of subcarrier activation patterns are discarded to retain a part of indices to convey index bits, which causes the loss of spectral efficiency. In this paper, we proposed a novel technique to combine indices of a part of subblocks, called OFDM with joint subblocks index modulation (OFDM-JS-IM), which is capable of enhancing the spectral efficiency and energy efficiency without extra energy consumption compared to OFDM-IM. The length of joint subblocks is also discussed to properly enhance spectral efficiency. Moreover, near the maximum-likelihood detector and low-complexity log-likelihood ratio detector are proposed to mitigate the high burden caused by joint subblocks. Theoretical analysis based on pairwise error probability is conducted which fits well with the simulation results. The Monte Carlo simulations show that the proposed scheme achieves improvement of spectral efficiency with slight performance loss in comparison with OFDM-IM.