Precoded Index Modulation Based Multiple Access Scheme

The recently proposed Index Modulation based Multiple Access (IMMA) has shown a superior performance in terms of the error performance, and the number of served users when compared to the conventional schemes. However, the accompanied high computational complexity poses a significant challenge for its practical deployment. In this paper, a Precoded IMMA (P-IMMA) scheme is proposed that is able not only to reduce the high computational complexity at the receiver, but it also achieves better error performance, and higher security level. The proposed P-IMMA scheme adopts channel pre-equalization, power scaling, and phase adjustment at the users' side to accomplish the aforementioned advantages. The performance of the proposed scheme in terms of the average bit error rate (BER), and the computational complexity is mathematically analyzed, and validated by Monte Carlo simulations. Results show that P-IMMA can beat IMMA in terms of the average BER, the computational complexity, and the physical-layer security.