Performance Analysis of Improved Subcarrier Index Modulation OFDM Using a Novel Decision Rule over AWGN Link

Abstract

Subcarrier Index Modulation Orthogonal Frequency Division Multiplexing (SIM-OFDM) is a modulation technique that extends information transmission beyond conventional subcarriers, incorporating their presence or absence. However, inaccurate determination of subcarrier status at the receiver can result in a high Bit Error Rate (BER). In response, this paper introduces an enhanced version named Improved SIM-OFDM (iSIM-OFDM). iSIM-OFDM employs a novel decision rule based on the summation of absolute values of the real and imaginary parts of each received symbol. Through simulations conducted over an Additive White Gaussian Noise (AWGN) link using Python, we performed a comparative study with conventional SIM-OFDM, specifically focusing on the electrical energy-per-bit per noise ratio E b ÚN 0 for various constellation sizes. The results reveal that iSIM-OFDM outperforms conventional SIM-OFDM in terms of BER performance, achieving a maximum gain in E b ÚN 0 of up to 2dB. This improvement is followed by the added advantage of reduced computational complexity while maintaining equivalent spectral efficiency. Furthermore, in the context of Power Reallocation Policy (PRP) versus Power Saving Policy (PSP), iSIM-OFDM achieves a gain of approximately 3 dB in E b ÚN 0 with PRP. Additionally, iSIM-OFDM demonstrates similar BER performance in PRP policy with only half the transmitted power compared to PSP policy. Considering these aspects, iSIM-OFDM emerges as a robust candidate in wireless communication fields where energy constraints are stringent, and rapid computational processing is imperative.