Orthogonal time frequency space (OTFS) offers significant advantages in managing mobility for both wireless sensing and communication systems, making it a promising candidate for dual-functional radar-communication (DFRC). However, the optimal signal design that fully exploits OTFS's potential in DFRC has not been sufficiently explored. This paper addresses this gap by formulating an optimization problem for signal design in DFRC-OTFS, incorporating both pilot-symbol design for channel estimation and data-power allocation. Specifically, we employ the integrated sidelobe level (ISL) of the ambiguity function as a radar metric, accounting for the randomness of the data symbols alongside the deterministic pilot symbols. For communication, we derive a channel capacity lower bound metric that considers channel estimation errors in OTFS. We maximize the weighted sum of sensing and communication metrics and solve the optimization problem via an alternating optimization framework. Simulations indicate that the proposed signal significantly improves the sensing-communication performance region compared with conventional signal schemes, achieving at least a 9.44 dB gain in ISL suppression for sensing, and a 4.82 dB gain in the signal-to-interference-plus-noise ratio (SINR) for communication.

翻译：正交时频空间（OTFS）调制在无线感知与通信系统中处理移动性方面具有显著优势，使其成为双功能雷达通信（DFRC）的有力候选方案。然而，能够充分发挥OTFS在DFRC中潜力的最优信号设计尚未得到充分探索。本文通过构建一个针对DFRC-OTFS系统的信号设计优化问题来填补这一空白，该问题同时考虑了用于信道估计的导频符号设计和数据功率分配。具体而言，我们采用模糊函数的积分旁瓣电平（ISL）作为雷达性能度量，该度量同时考虑了数据符号的随机性和导频符号的确定性。对于通信性能，我们推导了一个考虑OTFS信道估计误差的信道容量下界度量。我们通过最大化感知与通信度量的加权和，并采用交替优化框架来求解该优化问题。仿真结果表明，与传统信号方案相比，所提出的信号设计显著扩展了感知-通信性能区域，在感知方面实现了至少9.44 dB的ISL抑制增益，在通信方面实现了4.82 dB的信号与干扰加噪声比（SINR）增益。