Wideband Index Modulation with Circularly-Shifted Chirps

TL;DR

This paper introduces a novel wideband index modulation scheme using circularly-shifted chirps, leveraging Golay complementary pairs derived from Fourier series of chirps, with low-complexity DFT-s-OFDM implementation and improved PMEPR and spectral efficiency.

Contribution

It presents a new wideband index modulation method based on circularly-shifted chirps and Golay pairs, with a low-complexity transmitter/receiver design and trade-offs between PMEPR and spectral efficiency.

Findings

Limits PMEPR effectively while exploiting frequency resources.

Demonstrates improved spectral efficiency compared to traditional schemes.

Provides a comprehensive simulation comparison with existing methods.

Abstract

In this study, we propose a wideband index modulation (IM) based on circularly-shifted chirps. To derive the proposed method, we first prove that a Golay complementary pair (GCP) can be constructed by linearly combining the Fourier series of chirps. We show that Fresnel integrals and/or Bessel functions, arising from sinusoidal and linear chirps, respectively, can lead to GCPs. We then exploit discrete Fourier transform-spread orthogonal frequency division multiplexing (DFT-s-OFDM) to obtain a low-complexity transmitter and receiver. We also discuss its generalization for achieving a trade-off between peak-to-mean envelope power ratio (PMEPR) and spectral efficiency (SE). Through comprehensive simulations, we compare the proposed scheme with DFT-s-OFDM with IM, orthogonal frequency division multiplexing (OFDM) with IM and complementary sequences (CSs) from Reed-Muller (RM) code. Our numerical results show that the proposed method limits the PMEPR while exploiting the frequency.