Index Modulation for Integrated Sensing and Communications: A Signal Processing Perspective

TL;DR

This paper reviews recent advances in index modulation (IM) techniques for integrated sensing and communications (ISAC), highlighting how IM enhances spectrum and hardware efficiency while supporting radar and communication functionalities.

Contribution

It provides a comprehensive analysis of IM-ISAC, detailing the analytical foundations and key applications, and discusses recent research developments in this emerging field.

Findings

IM improves energy and spectral efficiency in ISAC systems

IM enables dual-function radar and communication performance

Recent studies demonstrate practical implementation benefits

Abstract

A joint design of both sensing and communication can lead to substantial enhancement for both subsystems in terms of size, cost as well as spectrum and hardware efficiency. In the last decade, integrated sensing and communications (ISAC) has emerged as a means to efficiently utilize the spectrum on a single and shared hardware platform. Recent studies focused on developing multi-function approaches to share the spectrum between radar sensing and communications. Index modulation (IM) is one particular approach to incorporate information-bearing communication symbols into the emitted radar waveforms. While IM has been well investigated in communications-only systems, the implementation adoption of IM concept in ISAC has recently attracted researchers to achieve improved energy/spectral efficiency while maintaining satisfactory radar sensing performance. This article focuses on recent studies on IM-ISAC, and presents in detail the analytical background and relevance of the major IM-ISAC applications.