Towards the upcoming 6G wireless networks, integrated sensing and communication (ISAC) has been identified as one of the typical usage scenarios. To further enhance the performance of ISAC, increasing the number of antennas as well as array aperture is one of the effective approaches. However, simply increasing the number of antennas will increase the cost of radio frequency chains and power consumption. To address this issue, in this paper, we consider an uplink ISAC system with nested array deployed at the base station. Nested array is a classic sparse array architecture that is able to enlarge the array aperture without increasing the number of physical antennas. While nested array for wireless sensing has been extensively studied, its potential for ISAC system has not been fully exploited. To fill this gap, in this paper, we provide the beam pattern analysis of nested arrays, and derive the closed-form expressions for the three beam pattern metrics, namely, the main lobe beam width, peak-to-local-minimum ratio, and prominent side lobes height. Extensive simulation results are provided to show that compared with conventional uniform arrays, nested arrays can achieve higher communication performance for densely located users while maintaining its advantage of sensing.

翻译：面向即将到来的第六代无线网络，集成感知与通信已被确立为典型应用场景之一。为提升集成感知与通信系统的性能，增加天线数量与阵列孔径是有效途径之一。然而，单纯增加天线数量将导致射频链成本与功耗上升。为解决该问题，本文研究在基站端部署嵌套阵列的上行集成感知与通信系统。嵌套阵列作为一种经典稀疏阵列架构，能够在无需增加物理天线数量的前提下扩大阵列孔径。尽管嵌套阵列在无线感知领域已得到广泛研究，其在集成感知与通信系统中的潜力尚未被充分挖掘。为填补这一空白，本文系统分析了嵌套阵列的波束方向图特性，并推导出三项波束方向图指标的闭式表达式，包括主瓣波束宽度、峰值与局部最小值比以及显著旁瓣高度。大量仿真结果表明，与传统均匀阵列相比，嵌套阵列在保持其感知优势的同时，能为密集分布的用户实现更高的通信性能。