MIMO-OFDM ISAC系统的时延-多普勒感知性能分析
Delay-Doppler Sensing Performance Analysis for MIMO-OFDM ISAC Systems
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中文总结 AI 辅助
本文分析多天线OFDM-ISAC系统的时延-多普勒感知性能，推导匹配滤波与互易滤波下的RDM二阶矩，揭示多流效应对动态范围的影响，验证两种滤波的几何依赖特性。
中文摘要 AI 辅助
在以通信为中心的集成感知与通信（ISAC）中，时延-多普勒感知复用承载数据的正交频分复用（OFDM）信号，而非专用雷达探测波形。因此，生成的距离-多普勒图（RDM）不仅受目标参数影响，还受通信符号随机性以及多天线传输中的空间波束成形影响。现有分析大多聚焦于单天线OFDM-ISAC，而多天线OFDM-ISAC的时延-多普勒感知行为仍未得到充分理解。本文分析了多输入多输出（MIMO）-OFDM-ISAC系统，其中多个数据流共同照射感知目标。推导了匹配滤波（MF）和互易滤波（RF）下RDM的二阶矩表达式，并用于表征动态范围（DR）。分析揭示了两个关键的多流效应：第一，在MF下，多个波束成形流的随机叠加会在调制相关项和接收机噪声项之外产生额外的RDM基底，因此恒模信号传输无法像单天线OFDM-ISAC那样消除数据诱导的基底；第二，在RF下，匹配角度的数据诱导基底被消除，但噪声基底会根据波束成形目标照射的互易功率统计而放大。这些结果表明，用户-目标的角几何直接决定了MF/RF的权衡：MF在弱照射下更鲁棒，而当互易噪声放大较温和时，RF可实现更高的DR。数值结果验证了该分析，并展示了MF和RF依赖几何的不同行为。
英文摘要
In communication-centric integrated sensing and communication (ISAC), delay-Doppler sensing reuses data-bearing orthogonal frequency division multiplexing (OFDM) signals rather than dedicated radar probing waveforms. Consequently, the resulting range-Doppler map (RDM) is shaped not only by target parameters, but also by communication-symbol randomness and, in multi-antenna transmissions, by spatial beamforming. While existing analyses have largely focused on single-antenna OFDM-ISAC, the delay-Doppler sensing behavior of multi-antenna OFDM-ISAC remains insufficiently understood. This paper analyzes a multi-input multi-output (MIMO)-OFDM-ISAC system in which multiple data streams jointly illuminate a sensing target. We derive second-order moment expressions for the RDM under matched filtering (MF) and reciprocal filtering (RF), and use them to characterize the dynamic range (DR). The analysis reveals two key multi-stream effects. First, under MF, the random superposition of multiple beamformed streams creates an additional RDM floor beyond the modulation-dependent and receiver-noise terms; therefore, constant-modulus signaling no longer eliminates the data-induced pedestal as in single-antenna OFDM-ISAC. Second, under RF, the matched-angle data-induced floor is removed, but the noise floor is amplified according to the reciprocal-power statistics of the beamformed target illumination. These results show that the user-target angular geometry directly governs the MF/RF tradeoff: MF is more robust under weak illumination, whereas RF can achieve a higher DR when reciprocal-noise amplification is mild. Numerical results validate the analysis and demonstrate the distinct geometry-dependent behaviors of MF and RF.
发表机构
- Dalian University of Technology（大连理工大学）
- Friedrich-Alexander-University Erlangen-Nuremberg (FAU)（埃尔朗根-纽伦堡弗里德里希·亚历山大大学）
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