In this work, we study integrated sensing and communication (ISAC) networks with the aim of effectively balancing sensing and communication (S&C) performance at the network level. Focusing on monostatic sensing, the tool of stochastic geometry is exploited to capture the S&C performance, which facilitates us to illuminate key cooperative dependencies in the ISAC network and optimize key network-level parameters. Based on the derived tractable expression of area spectral efficiency (ASE), we formulate the optimization problem to maximize the network performance from the view point of two joint S&C metrics. Towards this end, we further jointly optimize the cooperative BS cluster sizes for S&C and the serving/probing numbers of users/targets to achieve a flexible tradeoff between S&C at the network level. It is verified that interference nulling can effectively improve the average data rate and radar information rate. Surprisingly, the optimal communication tradeoff for the case of the ASE maximization tends to employ all spacial resources towards multiplexing and diversity gain, without interference nulling. By contrast, for the sensing objectives, resource allocation tends to eliminate certain interference especially when the antenna resources are sufficient, because the inter-cell interference becomes a more dominant factor affecting sensing performance. Furthermore, we prove that the ratio of the optimal number of users and the number of transmit antennas is a constant value when the communication performance is optimal. Simulation results demonstrate that the proposed cooperative ISAC scheme achieves a substantial gain in S&C performance at the network level.

翻译：本文研究通感一体化（ISAC）网络，旨在网络层面有效平衡感知与通信（S&C）性能。聚焦单站感知场景，利用随机几何工具刻画S&C性能，从而揭示ISAC网络中的关键协作依赖关系并优化网络级参数。基于推导出的区域频谱效率（ASE）可处理表达式，从两个联合S&C指标角度构建网络性能最大化优化问题。为此，我们进一步联合优化S&C协作基站簇大小、服务/探测用户/目标数量，以实现网络层面灵活的S&C权衡。验证表明，干扰置零可有效提升平均数据速率与雷达信息速率。有趣的是，在ASE最大化情形下，通信优化策略倾向于将全部空间资源用于复用与分集增益，而不采用干扰置零；相反，对于感知目标，资源分配倾向于消除特定干扰——尤其当天线资源充足时，因为此时小区间干扰成为影响感知性能的主导因素。此外，我们证明当通信性能最优时，最优用户数与发射天线数之比为恒定值。仿真结果表明，所提协作ISAC方案在网络层面实现了显著的S&C性能增益。