Super-Mode OFDM with Index Modulation

TL;DR

This paper introduces super-mode OFDM with index modulation (SuM-OFDM-IM), a novel scheme that enhances spectral efficiency and error performance for 5G by jointly selecting mode and subcarrier activation patterns and employing repetition coding.

Contribution

The paper proposes a new SuM-OFDM-IM scheme with joint pattern selection and repetition coding, along with a low-complexity detector, theoretical analysis, and real-time SDR implementation.

Findings

Promising spectral efficiency improvements

Enhanced error performance demonstrated

Effective in real-time SDR experiments

Abstract

Orthogonal frequency division multiplexing (OFDM) with index modulation (OFDM-IM) appears as a promising multi-carrier waveform candidate for beyond 5G due to its attractive advantages such as operational flexibility and ease of implementation. However, OFDM-IM may not be a proper choice for 5G services such as enhanced mobile broadband (eMBB) since achieving high data rates is challenging because of its null subcarriers. One solution to enhance the spectral efficiency of OFDM-IM is the employment of multiple distinguishable constellations (modes) by also exploiting its null subcarriers for data transmission. This paper proposes a novel IM technique called super-mode OFDM-IM (SuM-OFDM-IM), where mode activation patterns (MAPs) and subcarrier activation patterns (SAPs) are jointly selected and conventional data symbols are repetition coded over multiple subcarriers to achieve a diversity gain. For the proposed scheme, a low-complexity detector is designed, theoretical analyses are performed and a bit error rate (BER) upper bound is derived. The performance of the proposed system is also investigated through real-time experiments using a software-defined radio (SDR) based prototype. We show that SuM-OFDM-IM exhibits promising results in terms of spectral efficiency and error performance; thus, appears as a potential candidate for 5G and beyond communication systems.