This paper studies a multi-antenna networked integrated sensing and communications (ISAC) system, in which a set of multi-antenna base stations (BSs) employ the coordinated transmit beamforming to serve multiple single-antenna communication users (CUs) and perform joint target detection by exploiting the reflected signals simultaneously. To facilitate target sensing, the BSs transmit dedicated sensing signals combined with their information signals. Accordingly, we consider two types of CU receivers with and without the capability of canceling the interference from the dedicated sensing signals, respectively. In addition, we investigate two scenarios with and without time synchronization among the BSs. For the scenario with synchronization, the BSs can exploit the target-reflected signals over both the direct links (BS-to-target-to-originated BS links) and the cross-links (BS-to-target-to-other BSs links) for joint detection, while in the unsynchronized scenario, the BSs can only utilize the target-reflected signals over the direct links. For each scenario under different types of CU receivers, we optimize the coordinated transmit beamforming at the BSs to maximize the minimum detection probability over a particular targeted area, while guaranteeing the required minimum signal-to-interference-plus-noise ratio (SINR) constraints at the CUs. These SINR-constrained detection probability maximization problems are recast as non-convex quadratically constrained quadratic programs (QCQPs), which are then optimally solved via the semi-definite relaxation (SDR) technique.

翻译：本文研究了一种多天线网络化集成感知与通信（ISAC）系统，其中一组多天线基站（BS）采用协同发射波束赋形技术，同时服务于多个单天线通信用户（CU），并利用反射信号执行联合目标检测。为促进目标感知，基站在其信息信号中叠加发射专用感知信号。据此，我们分别考虑了两类CU接收机：具备和不具备消除专用感知信号干扰能力的场景。此外，我们研究了基站间有无时间同步的两种情形。在同步场景中，基站可利用目标反射信号在直达链路（基站-目标-源基站链路）和交叉链路（基站-目标-其他基站链路）上实现联合检测；而在非同步场景中，基站仅能利用直达链路上的目标反射信号。针对不同CU接收机类型的每种场景，我们优化了基站的协同发射波束赋形，以最大化特定目标区域的最小检测概率，同时保证CU所需的最小信干噪比（SINR）约束。这些受SINR约束的检测概率最大化问题被转化为非凸二次约束二次规划（QCQP），并通过半定松弛（SDR）技术求得最优解。