Orthogonal frequency division multiplexing index modulation (OFDM-IM) has been emerging as a promising solution to increase the reliability at low complexity. However, the transmit diversity of the OFDM-IM schemes has been limited to two, due to unbalanced transmit diversity between index bits and complex data bits. In this work, we propose a new precoded OFDM-IM employing several spread matrices, named as (S-OFDM-IM). This aims to increase the transmit diversity, exploiting not only a subset of active sub-carrier indices, but also spreading the active indices over all the sub-carriers available. In this context, the transmit diversity in the detection of both index bits and data bits will be increased, properly taking into account both the multipath and index diversities. As for low-complexity detection, we propose two linear-complexity detections that exploit the minimum mean square error and the zero-forcing, along with the likelihood ratio. To analyse the performance, the bit error probability is derived and the transmit diversity analysis is provided. Through simulation results, it is clearly presented that the proposed scheme can outperform the benchmarks in terms of the transmit diversity, being higher than two. The enhanced transmit diversity is desired to the lowcomplexity machine type applications with high reliability.
|Conference||87th IEEE Vehicular Technology Conference, VTC Spring 2018|
|Period||03/06/2018 → 06/06/2018|