We consider a joint radar parameter estimation and communication system using orthogonal time frequency space (OTFS) modulation. The scenario is motivated by vehicular applications where a vehicle (or the infrastructure) equipped with a mono-static radar wishes to communicate data to its target receiver, while estimating parameters of interest related to this receiver. Provided that the radar-equipped transmitter is ready to send data to its target receiver, this setting naturally assumes that the receiver has been already detected. In a point-to-point communication setting over multipath time-frequency selective channels, we study the joint radar and communication system from two perspectives, i.e., the radar parameter estimation at the transmitter as well as the data detection at the receiver. For the radar parameter estimation part, we derive an efficient approximated Maximum Likelihood algorithm and the corresponding Cramér-Rao lower bound for range and velocity estimation. Numerical examples demonstrate that multi-carrier digital formats such as OTFS can achieve as accurate radar estimation as state-of-the-art radar waveforms such as frequency-modulated continuous wave (FMCW). For the data detection part, we focus on separate detection and decoding and consider a soft-output detector that exploits efficiently the channel sparsity in the Doppler-delay domain. We quantify the detector performance in terms of its pragmatic capacity, i.e., the achievable rate of the channel induced by the signal constellation and the detector soft-output. Simulations show that the proposed scheme outperforms concurrent state-of-the-art solutions. Overall, our work shows that a suitable digitally modulated waveform enables to efficiently operate joint radar parameter estimation and communication by achieving full information rate of the modulation and near-optimal radar estimation performance. Furthermore, OTFS appears to be particularly suited to the scope.

中文翻译：

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论OTFS联合雷达参数估计和通信的有效性


我们考虑使用正交时频空间（OTFS）调制的联合雷达参数估计和通信系统。该场景是由车辆应用激发的，其中配备单静态雷达的车辆（或基础设施）希望将数据传送到其目标接收器，同时估计与该接收器相关的感兴趣参数。如果配备雷达的发射器已准备好向其目标接收器发送数据，则此设置自然假设接收器已被检测到。在多径时频选择性信道上的点对点通信环境中，我们从发射机的雷达参数估计和接收机的数据检测两个角度研究联合雷达和通信系统。对于雷达参数估计部分，我们推导了一种有效的近似最大似然算法以及相应的距离和速度估计的 Cramér-Rao 下界。数值示例表明，OTFS 等多载波数字格式可以实现与调频连续波 (FMCW) 等最先进的雷达波形一样精确的雷达估计。对于数据检测部分，我们专注于单独的检测和解码，并考虑有效利用多普勒延迟域中的信道稀疏性的软输出检测器。我们根据检测器的实用能力来量化检测器的性能，即由信号星座和检测器软输出引起的通道的可实现速率。仿真表明，所提出的方案优于并发的最先进的解决方案。 总的来说，我们的工作表明，合适的数字调制波形能够通过实现调制的完整信息率和接近最佳的雷达估计性能来有效地操作联合雷达参数估计和通信。此外，OTFS 似乎特别适合该范围。