On the SEP Analysis of OFDM Index Modulation With Hybrid Low Complexity Greedy Detection and Diversity Reception

In this work, we investigate the performance of multicarrier index keying (MCIK) orthogonal frequency division multiplexing (OFDM) proposing a hybrid low complexity detection and diversity reception. For performance analysis, we derive novel exact closed-form expressions for the average pairwise error probability (PEP) and symbol error probability (SEP) of three detection methods: a greedy detector (GD), and a GD with maximal ratio combining, or selection combining. Approximate and accurate expressions for the average PEP and SEP are also analyzed in closed-form. The derived expressions provide a useful insight into the error performance of MCIK-OFDM with the hybrid detector in low, moderate, and extreme rate of sparse sub-carrier indices activation. The effects of multiple antennas and sparse sub-carriers activation on the SEP are addressed in several extreme cases; decreasing the average SEP exponentially with proper choice of both subcarrier activation rate and number of antennas. In comparison with the benchmark detection, the numerical results and simulations clearly show that the proposed schemes can benefit from diversity gain, at substantially reduced complexity. The derived SEP expressions and analyses will be useful to evaluate various concepts of MCIK OFDM in low-power device applications.