Frequency-hopping (FH) MIMO radar-based dual-function radar communication (FH-MIMO DFRC) enables communication symbol rate to exceed radar pulse repetition frequency, which requires accurate estimations of timing offset and channel parameters. The estimations, however, are challenging due to unknown, fast-changing hopping frequencies and the multiplicative coupling between timing offset and channel parameters. In this paper, we develop accurate methods for a single-antenna communication receiver to estimate timing offset and channel for FH-MIMO DFRC. First, we design a novel FH-MIMO radar waveform, which enables a communication receiver to estimate the hopping frequency sequence (HFS) used by radar, instead of acquiring it from radar. Importantly, the novel waveform incurs no degradation to radar ranging performance. Then, via capturing distinct HFS features, we develop two estimators for timing offset and derive mean squared error lower bound of each estimator. Using the bounds, we design an HFS that renders both estimators applicable. Furthermore, we develop an accurate channel estimation method, reusing the single hop for timing offset estimation. Validated by simulations, the accurate channel estimates attained by the proposed methods enable the communication performance of DFRC to approach that achieved based on perfect timing and ideal knowledge of channel.

中文翻译：

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跳频 MIMO 雷达通信的波形设计和精确信道估计

基于跳频 (FH) MIMO 雷达的双功能雷达通信 (FH-MIMO DFRC) 使通信符号率能够超过雷达脉冲重复频率，这需要准确估计时序偏移和信道参数。然而，由于未知的、快速变化的跳频以及定时偏移和信道参数之间的乘法耦合，估计具有挑战性。在本文中，我们为单天线通信接收机开发了准确的方法来估计 FH-MIMO DFRC 的定时偏移和信道。首先，我们设计了一种新颖的 FH-MIMO 雷达波形，它使通信接收器能够估计雷达使用的跳频序列 (HFS)，而不是从雷达获取它。重要的是，新波形不会降低雷达测距性能。然后，通过捕获不同的 HFS 特征，我们开发了两个用于时序偏移的估计器，并推导出每个估计器的均方误差下限。使用边界，我们设计了一个 HFS，使两个估计器都适用。此外，我们开发了一种精确的信道估计方法，重用单跳进行定时偏移估计。通过仿真验证，所提出的方法获得的准确信道估计使 DFRC 的通信性能接近基于完美时序和理想信道知识所实现的性能。