Orthogonal Frequency Division Multiplexing With Generalized Joint Index Modulation

Orthogonal frequency division multiplexing with index modulation (OFDM-IM) is a promising multi-carrier technique for next generation wireless communication networks. In this paper, we propose a generalized joint OFDM-IM scheme, which performs joint modulation on multiple subsubblocks divided from a subblock, to achieve higher spectral efficiency (SE) and lower complexity for both modulation and detection processes. In GJ-OFDM-IM, the subcarrier activation pattern (SAP) of the subblock is composed of the SAPs of all the sub-subblocks within the subblock, which means a large dimensions IM of the subblock is divided into multiple small size IM of the sub-subblocks by taking advantage of the joint modulation. With the aid of joint modulation, the lookup tables for both modulation and demodulation are only related with the size of sub-subblock and not changed with the size of the subblock. At the receiver, the optimal maximum likelihood (ML) detector and a low complexity subblock wise detector are proposed for GJ-OFDM-IM. Then, a tight upper bound on the bit error rate (BER) is derived in closed form to evaluate the system performance of the proposed GJ-OFDM-IM. Simulation and numerical results verify the analysis and show that the proposed GJ-OFDM-IM can greatly reduce the implementation complexity without causing any system BER performance loss compared with classical OFDM-IM.