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.

翻译：集成感知与通信（ISAC）被认为是支持物联网（IoT）等应用场景的关键使能技术，在这些场景中通信与感知均发挥着重要作用。多载波波形（如正交频分复用（OFDM））因其高通信数据速率和良好的感知时宽带宽特性，已被视为ISAC的优选方案。然而，其高峰均功率比（PAPR）值会导致性能下降或系统复杂度增加。这使得OFDM可能不适用于在功率、系统复杂度、硬件尺寸或成本方面资源不足的物联网应用。本文提出了以物联网为中心的恒定包络波形设计方案，这些方案利用单位PAPR的优势，因而更适用于资源受限的场景。具体而言，研究考虑了多种单载波频率和/或相位调制波形。基于雷达模糊函数、带宽特性、数据速率及通信接收机复杂度等性能指标，对其雷达感知与通信性能进行了全面讨论。