A closed-form symbol error probability for MCIK-OFDM with frequency diversity

Abstract

This paper proposes a novel scheme of Multi-carrier Index Keying — Orthogonal Frequency Division Multiplexing (MCIK-OFDM), called as repeated MCIK-OFDM (ReMO), which is capable of improving the error performance compared to classical MCIK-OFDM for a given spectral efficiency. Similar to the classical MCIK-OFDM, ReMO activates only a subset of sub-carriers to carry information bits by the use of both the active sub-carriers and their indices. However, unlike the classical scheme, ReMO exploits the frequency diversity such that the same M-ary data symbol is repeatedly used to modulate all the active sub-carriers. To gain an insight into the ReMO performance, a closed-form expression for the symbol error probability (SEP) is derived. This expression can help us analyze the impact of the ReMO parameters on the symbol error performance and suggest the best ReMO setup to minimize the error probability. Through both theoretical and simulation results, ReMO is successfully proved to provide significantly better diversity order as well as SEP error performance over the conventional OFDM and MCIK-OFDM at the same spectral efficiency.