OFDM-ISAC数据载荷中的星座设计：从MSE分析到实验验证

中文摘要 AI 辅助

正交频分复用（OFDM）因其高频谱效率及与现代通信标准的兼容性，成为集成感知与通信（ISAC）系统中最广泛采用的波形之一。本文研究了在特定雷达接收机处理方案下，基于OFDM的ISAC系统在多目标时延（距离）估计中的感知性能。我们开发了一个估计理论框架，用以表征随机通信载荷下的感知性能。通过推导使用匹配滤波（MF）和互易滤波（RF）接收机时均方误差（MSE）的闭式表达式，我们确立了时延估计精度的基本极限。结果表明，在多目标场景中，信号星座对时延估计MSE的影响因接收机而异：在存在多个目标时，MF性能取决于零均值、单位功率星座的四阶矩，而RF性能则取决于其逆二阶矩，且与目标数量无关。基于此分析，我们提出了一种在特定接收机架构下的ISAC星座设计，该设计在OFDM-ISAC系统中带来了依赖于接收机的感知与通信之间的灵活权衡。理论发现通过仿真和概念验证实验得到验证，并且所提出的星座设计在实验中展示了感知与通信性能的权衡。

英文摘要

Orthogonal frequency division multiplexing (OFDM) is one of the most widely adopted waveforms for integrated sensing and communication (ISAC) systems, owing to its high spectral efficiency and compatibility with modern communication standards. This paper investigates the sensing performance of OFDM-based ISAC for multi-target delay (range) estimation under specific radar receiver processing schemes. An estimation-theoretic framework is developed to characterize sensing performance with random communication payloads. We establish the fundamental limit of delay estimation accuracy by deriving the closed-form expression of the mean-square error (MSE) achieved using matched filtering (MF) and reciprocal filtering (RF) receivers. The results show that, in multi-target scenarios, the impact of signal constellations on the delay estimation MSE differs across receivers: MF performance depends on the fourth-order moment of the zero-mean, unit-power constellation in the presence of multiple targets, whereas RF performance depends on its inverse second-order moment, irrespective of the number of targets. Building on this analysis, we present a ISAC constellation design under specific receiver architecture that brings a receiver-dependent flexible trade-off between sensing and communication in OFDM-ISAC systems. The theoretical findings are validated through simulations and proof-of-concept experiments, and also the sensing and communication performance trade-off is experimentally shown with the proposed constellation design.

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6 pages