This paper investigates a novel underlaid sensing pilot signal design for integrated sensing and communications (ISAC) in an OFDM-based communication system. The proposed two-dimensional (2D) pilot signal is first generated on the delay-Doppler (DD) plane and then converted to the time-frequency (TF) plane for multiplexing with the OFDM data symbols. The sensing signal underlays the OFDM data, allowing for the sharing of time-frequency resources. In this framework, sensing detection is implemented based on a simple 2D correlation, taking advantage of the favorable auto-correlation properties of the sensing pilot. In the communication part, the sensing pilot, served as a known signal, can be utilized for channel estimation and equalization to ensure optimal symbol detection performance. The underlaid sensing pilot demonstrates good scalability and can adapt to different delay and Doppler resolution requirements without violating the OFDM frame structure. Experimental results show the effective sensing performance of the proposed pilot, with only a small fraction of power shared from the OFDM data, while maintaining satisfactory symbol detection performance in communication.

翻译：本文研究了一种面向正交频分复用(OFDM)通信系统中集成感知与通信(ISAC)的新型底层感知导频信号设计。所提出的二维(2D)导频信号首先在时延-多普勒(DD)平面上生成，随后转换至时频(TF)平面与OFDM数据符号进行复用。该感知信号以底层方式嵌入OFDM数据中，从而实现时频资源共享。在此框架下，利用感知导频优越的自相关特性，基于简单的二维相关运算即可实现感知检测。在通信部分，感知导频作为已知信号可用于信道估计与均衡，确保最优符号检测性能。所提底层感知导频具有良好的可扩展性，能够在不违反OFDM帧结构的前提下适应不同时延-多普勒分辨率需求。实验结果表明，该导频在仅从OFDM数据中共享极小部分功率的条件下即可实现有效感知性能，同时保持通信中令人满意的符号检测性能。