恒包络ISAC via FM-OFDM：分析框架与接收机设计
Constant-Envelope ISAC via FM-OFDM: Analytical Framework and Receiver Design
AI总结：
本文提出FM-OFDM作为恒包络ISAC解决方案，通过分析框架和定制接收机设计，在PA饱和区域实现高输出功率和低失真，验证其在硬件受限环境下的有效性。
AI中文摘要：
集成感知与通信（ISAC）系统面临严格的硬件限制，特别是在标准OFDM的高峰均功率比（PAPR）方面，这需要功率放大器（PA）回退并减少感知范围。本文研究了频率调制OFDM（FM-OFDM）作为一种恒包络解决方案，能够在其PA饱和区域运行，从而在不产生传统波形典型的非线性失真惩罚的情况下最大化输出功率。我们推导了FM-OFDM在双散射通道中的综合分析框架，明确量化了载波间干扰（ICI）动态和判别域中的有效信道增益。为了解决波形独特的相位结构，我们提出了一种定制的感知接收机架构，利用慢时间相位差分进行稳健的速度估计。与先前工作不同，我们评估了在严格归一化的带宽约束（B99）下的性能，确保与CP-OFDM和恒包络OFDM（CE-OFDM）的公平比较。仿真结果表明，即使在完全饱和的PA条件和高多普勒频移下，FM-OFDM仍能保持优越的检测精度和低误码率，验证了其在硬件受限的ISAC收发机中的适用性。
英文摘要：
Integrated Sensing and Communication (ISAC) systems face stringent hardware constraints, particularly regarding the high Peak-to-Average Power Ratio (PAPR) of standard OFDM, which necessitates power amplifier (PA) back-off and reduces sensing range. This paper investigates Frequency Modulated OFDM (FM-OFDM) as a constant-envelope solution capable of operating in the PA saturation region, thereby maximizing output power without the non-linear distortion penalties typical of conventional waveforms. We derive a comprehensive analytical framework for FM-OFDM in doubly dispersive channels, explicitly quantifying the inter-carrier interference (ICI) dynamics and effective channel gains in the discriminator domain. To address the unique phase structure of the waveform, we propose a tailored sensing receiver architecture utilizing slow time phase differencing for robust velocity estimation. Unlike prior works, we evaluate performance under a strictly normalized bandwidth constraint (B99), ensuring a fair comparison against CP-OFDM and Constant-Envelope OFDM (CE-OFDM). Simulation results demonstrate that FM-OFDM maintains superior detection accuracy and low BER even under fully saturated PA conditions and high Doppler shifts, validating its suitability for hardware-constrained ISAC transceivers.
