Subcarrier Index Modulation for Spectral Efficient Frequency Division Multiplexing in Multi-Input Multi-Output Channels

This work presents spectral efficient frequency division multiplexing with subcarrier index modulation (SEFDM-SIM) for multi-input multi-output (MIMO) wireless networks. SEFDM employs non-orthogonal frequency division multiplexing to enhance the spectral efficiency (SE) at the expense of enhanced inter-carrier interference compared with traditional orthogonal frequency division multiplexing (OFDM). In SEFDM-SIM, the information is conveyed not only by $M$-ary signal constellations, as in SEFDM, but also by the indices of the subcarriers, which are activated according to the incoming bitstream. SE and bit error rate (BER) are used as the performance measures. Both the analytic and simulation results show that the proposed MIMO-SEFDM-SIM outperforms the conventional MIMO-OFDM and MIMO-OFDM-SIM in SE, while achieving an improved BER than the MIMO-OFDM and MIMO-SEFDM systems.