Integrated sensing and communication (ISAC) has been recognized as one of the key technologies capable of simultaneously improving communication and sensing services in future wireless networks. Moreover, the introduction of recently developed movable antennas (MAs) has the potential to further increase the performance gains of ISAC systems. Although the gains of MA-enabled ISAC systems are relatively well studied in the far field, they remain almost unexplored in near-field scenarios. Motivated by this, in this paper we maximize the weighted sum rate (WSR) for communication users while maintaining a minimum sensing requirement in an MA-enabled near-field ISAC system. To achieve this goal, we propose algorithms that optimize the communication precoding matrices, the sensing transmit beamformer, the sensing receive combiner, the positions of the users' MAs and the positions of the base station (BS) transmit MAs in an alternating manner for the considered ISAC system, for the cases where linear procoding and zero-forcing (ZF) precoding are employed at the BS. Simulation results show that using MAs in near-field ISAC systems provides a substantial performance advantage compared to near-field ISAC systems equipped with fixed antennas only. We show that the scheme with linear precoding achieves larger WSR for unequal users' weight rates, while the scheme with ZF precoding maintains an approximately constant WSR for all users' weight rates. Additionally, we demonstrate that the WSRs of the proposed schemes are highly dependent on the inter-antenna interference between different user's MAs, and that the sensing performance is significantly more affected by the minimum sensing signal-to-interference-plus-noise ratio (SINR) threshold compared to the communication performance.

翻译：集成感知与通信（ISAC）已被认为是未来无线网络中能够同时提升通信与感知服务的关键技术之一。此外，近期发展的可移动天线（MAs）的引入有望进一步提升ISAC系统的性能增益。尽管基于MA的ISAC系统在远场中的增益已得到相对充分的研究，但在近场场景中其增益仍几乎未被探索。受此启发，本文在一个支持MA的近场ISAC系统中，在维持最低感知要求的同时，最大化通信用户的加权和速率（WSR）。为实现这一目标，我们针对所考虑的ISAC系统，在基站（BS）采用线性预编码和迫零（ZF）预编码的情况下，提出了交替优化通信预编码矩阵、感知发射波束成形器、感知接收合并器、用户MAs位置以及BS发射MAs位置的算法。仿真结果表明，与仅配备固定天线的近场ISAC系统相比，在近场ISAC系统中使用MAs能带来显著的性能优势。我们表明，线性预编码方案在用户权重速率不等时能实现更大的WSR，而ZF预编码方案对所有用户的权重速率均能保持近似恒定的WSR。此外，我们证明了所提方案的WSR高度依赖于不同用户MAs之间的天线间干扰，并且与通信性能相比，感知性能受最小感知信号与干扰加噪声比（SINR）阈值的影响显著更大。