索引调制辅助相位旋转AFDM用于高效集成传感与通信：框架、优化与性能分析
Index Modulation Aided Phase-Rotated AFDM for Efficient Integrated Sensing and Communication: Framework, Optimization and Performance Analysis
- Beijing Institute of Technology（北京理工大学）
- University of Essex（埃塞克斯大学）
- Tsinghua University（清华大学）
- Tsinghua Shenzhen International Graduate School（清华深圳国际研究生院）
- South China University of Technology（华南理工大学）
- University College London（伦敦大学学院）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文提出PLIM-PR-AFDM方案，通过功率电平索引调制嵌入相位旋转SI，联合优化功率分配与相位旋转以抑制PAPR和AF旁瓣，同时补偿频谱效率损失，并推导了误码性能上界。
AI中文摘要：
仿射频分复用（AFDM）已成为高机动场景下集成传感与通信（ISAC）的一种有竞争力的波形，但其数据依赖的高峰均功率比（PAPR）和模糊函数（AF）旁瓣可能会降低功率放大器效率以及传感性能。为缓解这些问题，一个有前景的候选方案是相位旋转优化理念，该理念需要辅助侧信息（SI）来确保接收端的数据恢复成功。然而，使用额外的信令开销来传递SI会降低频谱效率。在此背景下，本文提出了一种功率电平索引调制（PLIM）辅助的相位旋转AFDM（PLIM-PR-AFDM）方案，该方案将相位旋转SI嵌入到传输块内。在发射端，所提方案通过协调PLIM功率分配、相位旋转和SI嵌入来联合优化波形。具体而言，子载波被灵活分配不同的发射功率电平。高功率子载波进行相位旋转以抑制PAPR和快慢时AF旁瓣。通过将快慢时AF旁瓣能量分解为逐块周期自相关函数（PACF）项，传感目标可表述为PACF加权积分旁瓣电平（WISL）最小化问题，而选定的低功率子载波通过星座标签嵌入相位比特作为SI。此外，每个传输块的PLIM功率模式可携带额外的索引比特，这补偿了SI传输引起的频谱效率损失。此外，通过推导平均误比特概率（ABEP）的上界并确定全分集条件，分析了错误性能。
英文摘要：
Affine frequency division multiplexing (AFDM) has emerged as a competitive waveform for integrated sensing and communication (ISAC) in high-mobility scenarios, but its data-dependent high peak-to-average power ratio (PAPR) and ambiguity function (AF) sidelobes may degrade the power-amplifier efficiency as well as the sensing performance. To mitigate the issues, one promising candidate is the phase-rotation optimization philosophy, which necessitates auxiliary side information (SI) to guarantee successful data recovery at the receiver. However, using additional signalling overhead to deliver the SI degrades the spectral efficiency. Against the background, this paper proposes a power level index modulation (PLIM)-aided phase-rotated AFDM (PLIM-PR-AFDM) scheme, which embeds the phase-rotation SI within the transmitted block. At the transmitter, the proposed scheme jointly optimizes the waveform by coordinating the PLIM power allocation, phase rotation, and embedding of SI. Specifically, subcarriers are flexibly allocated with different transmit power levels. High-power subcarriers are phase-rotated to suppress the PAPR and fast-slow-time AF sidelobes. By decomposing the fast-slow-time AF sidelobe energy into per-block periodic autocorrelation function (PACF) terms, the sensing objective can be formulated as a PACF-weighted integrated sidelobe level (WISL) minimization problem, while selected low-power subcarriers embed the phase bits as SI through constellation labels. Furthermore, the PLIM power patterns of each transmitted block can convey additional index bits, which compensates for the spectral efficiency loss caused by SI transmission. Moreover, the error performance is analyzed by deriving an upper bound of the average bit error probability (ABEP) and identifying the condition for full diversity.
