This paper investigates the Pareto boundary performance of a joint communication and sensing (JCAS) system that addresses both sensing and communication functions at the same time. In this scenario, a multiple-antenna base station (BS) transmits information to multiple single-antenna communication users while concurrently estimating the parameters of a single sensing object using the echo signal. We present an integrated beamforming approach for JCAS in a multi-user multiple-input and multiple-output (MIMO) system. The performance measures for communication and sensing are Fisher information (FI) and mutual information (MI). Our research considers two scenarios: multiple communication users with a single sensing object and a single communication user with a single sensing object. We formulate a multi-objective optimization problem to maximize the weighted sum of MI and FI, subject to a total transmit power budget for both cases. As a particular case, we address the equivalent isotropic radiated power (EIRP) for the single communication user scenario. We use the uplink-downlink duality for the multi-user case to simplify the problem and apply Lagrangian optimization and line search methods with a block-coordinate ascending technique. We use projected gradient descent (PGD) to solve the optimization problem in the single-user case. Our numerical results demonstrate that joint beamforming is optimal for the multi-user JCAS system, as opposed to independent beamforming for each user and the sensing object. Furthermore, we reveal the Pareto boundary for the multi-user case, with variations in the number of communication users and the number of transmitting and receiving antennas. We provide the Pareto boundary depending on EIRP limitations for the single-user case.

翻译：本文研究同时处理感知与通信功能的通信感知一体化系统的帕累托边界性能。在此场景中，一个多天线基站向多个单天线通信用户传输信息，同时利用回波信号估计单个感知目标的参数。我们提出了一种适用于多用户多输入多输出系统的通信感知一体化波束赋形方法。通信与感知的性能度量分别为费舍尔信息与互信息。本研究考虑两种场景：多通信用户单感知目标，以及单通信用户单感知目标。针对这两种情况，我们在总发射功率约束下，构建了以最大化互信息与费舍尔信息加权和为目标的多元优化问题。作为特例，我们探讨了单通信用户场景中的等效全向辐射功率约束。对于多用户场景，我们利用上下行对偶性简化问题，并采用拉格朗日优化与结合块坐标上升技术的线搜索方法。对于单用户场景，我们使用投影梯度下降法求解优化问题。数值结果表明，与为每个用户和感知目标独立设计波束赋形相比，联合波束赋形对多用户通信感知一体化系统是最优的。此外，我们通过改变通信用户数量、收发天线数量，揭示了多用户场景的帕累托边界。针对单用户场景，我们给出了依赖于等效全向辐射功率限制的帕累托边界。