Constant Modulus Waveforms for IoT-Centric Integrated Sensing and Communications

TL;DR

This paper proposes IoT-centric constant modulus waveforms for integrated sensing and communications, addressing PAPR issues in resource-constrained IoT scenarios by analyzing radar and communication performance metrics.

Contribution

It introduces novel constant modulus waveform designs tailored for IoT applications, improving resource efficiency over traditional OFDM-based methods.

Findings

Constant modulus waveforms have unit PAPR, suitable for resource-limited IoT devices.

The proposed waveforms offer competitive radar sensing and communication performance.

Performance analysis shows advantages in bandwidth, data rate, and complexity.

Abstract

Integrated sensing and communications (ISAC) is considered a key enabler to support application scenarios such as the Internet-of-Things (IoT) in which both communications and sensing play significant roles. Multi-carrier waveforms, such as orthogonal frequency division multiplexing (OFDM), have been considered as good candidates for ISAC due to their high communications data rate and good time bandwidth property for sensing. Nevertheless, their high peak-to-average-power-ratio (PAPR) values lead to either performance degradation or an increase in system complexity. This can make OFDM unsuitable for IoT applications with insufficient resources in terms of power, system complexity, hardware size or cost. This article provides IoT-centric constant modulus waveform designs that leverage the advantage of unit PAPR and thus are more suitable in resource-limited scenarios. More specifically, several single-carrier frequency and/or phase-modulated waveforms are considered. A comprehensive discussion on their radar sensing and communications performance is conducted based on performance metrics, including the radar ambiguity function, the bandwidth property, the data rate, and the communications receiver complexity.