OFDM With Hybrid Number and Index Modulation

TL;DR

This paper introduces a new OFDM-based transmission scheme that combines number and index modulation to enhance spectral and energy efficiency, particularly suitable for IoT applications with low modulation orders.

Contribution

It proposes a novel modulation technique that jointly changes subcarrier number and index, outperforming existing OFDM-SNM and OFDM-IM schemes in efficiency and reliability.

Findings

Superior spectral and energy efficiency at low modulation orders

BER performance aligns with analytical predictions

Suitable for IoT applications requiring low complexity and high reliability

Abstract

A novel transmission scheme is introduced for efficient data transmission by conveying additional information bits through jointly changing the index and number of active subcarriers within each orthogonal frequency division multiplexing (OFDM) subblock. The proposed scheme is different from the conventional OFDM-subcarrier number modulation (OFDM-SNM) and OFDM-index modulation (OFDM-IM), in which data bits are transmitted using either number or index of active subcarriers. The proposed modulation technique offers superior spectral and energy efficiency compared to its counterparts OFDM-SNM and OFDM-IM, especially at low modulation orders such as binary phase shift keying (BPSK) that can provide high reliability and low complexity, making it suitable for Internet of Things (IoT) applications that require better spectral and energy efficiency while enjoying high reliability and low complexity. Bit error rate (BER) performance analysis is provided for the proposed scheme, and Monte Carlo simulations are presented to prove the consistency of simulated BER with the analyzed one.