This paper studies the multi-antenna multicast channel with integrated sensing and communication (ISAC), in which a multi-antenna base station (BS) sends common messages to a set of single-antenna communication users (CUs) and simultaneously estimates the parameters of an extended target via radar sensing. We investigate the fundamental performance limits of this ISAC system, in terms of the achievable rate for communication and the estimation Cram\'er-Rao bound (CRB) for sensing. First, we derive the optimal transmit covariance in semi-closed form to balance the CRB-rate (C-R) tradeoff, and accordingly characterize the outer bound of a so-called C-R region. It is shown that the optimal transmit covariance should be of full rank, consisting of both information-carrying and dedicated sensing signals in general. Next, we consider a practical joint information and sensing beamforming design, and propose an efficient approach to optimize the joint beamforming for balancing the C-R tradeoff. Numerical results are presented to show the C-R region achieved by the optimal transmit covariance and the joint beamforming, as compared to other benchmark schemes.
翻译:本文研究多ANTANNA多频频道,该频道是一个多ANTANNA基站,向一组单一ANTAN通信用户发出共同信息,同时通过雷达遥感估计扩大目标的参数。我们从通信的可实现率和Cram\'er-Rao绑定(CRB)的测算角度调查该ISAC系统的基本性能限度。首先,我们以半封闭的形式得出最佳的传输通差,以平衡CRB-R交换率(C-R),并据此确定所谓的C-R区域的外部界限。我们发现,最佳传输的共变差应是完全的,既包括信息携带,也包括一般的专用感测信号。接下来,我们考虑一种实用的联合信息和感测成型设计,并提议一种高效的方法,优化C-R对C-R交易量的平衡联合成型。我们介绍了数字结果,以显示通过最佳传输和联合成型计划实现的C-R区域,与其他基准相比,显示最佳传输和联合成型计划所达到的C-R区域。