Extremely large aperture array (ELAA) is anticipated to serve as a pivotal feature of future multiple-input multiple-output (MIMO) systems in 6G. Near-field (NF) fading channel models are essential for reliable link-level simulation and ELAA system design. In this article, we propose a framework designed to generate NF fading channels for both communication and integrated sensing and communication (ISAC) applications. The framework allows a mixed of line of sight (LoS) and non-LoS (NLoS) links. It also considers spherical wave model and spatially non-stationary shadow fading. Based on this framework, we propose a three-dimensional (3D) fading channel model for ELAA systems deployed with a uniform rectangular array (URA). It can capture the impact of sensing object for ISAC applications. Moreover, all parameters involved in the framework are based on specifications or measurements from the 3rd Generation Partnership Project (3GPP) documents. Therefore, the proposed framework and channel model have the potential to contribute to the standard in various aspects, including ISAC, extra-large (XL-) MIMO, and reconfigurable intelligent surface (RIS) aided MIMO systems. Finally, future directions for ELAA are presented, including not only NF channel modeling but also the design of next-generation transceivers.

翻译：超大规模天线阵（ELAA）预计将成为未来6G多输入多输出（MIMO）系统的关键特征。近场（NF）衰落信道模型对于可靠的链路级仿真和ELAA系统设计至关重要。本文提出了一种用于生成通信与通感一体化（ISAC）应用中近场衰落信道的通用框架。该框架支持视距（LoS）与非视距（NLoS）链路的混合传输，并考虑了球面波模型与空间非平稳阴影衰落。基于此框架，我们提出了一种适用于均匀矩形阵列（URA）部署的ELAA系统三维（3D）衰落信道模型，该模型能够捕获ISAC应用中感知目标的影响。此外，框架中所有参数均基于第三代合作伙伴计划（3GPP）文件的规范或测量结果。因此，所提出的框架与信道模型有望从多个方面为标准化工作做出贡献，涵盖通感一体化、超大规模（XL-）MIMO以及可重构智能表面（RIS）辅助MIMO系统。最后，本文展望了ELAA的未来发展方向，不仅涉及近场信道建模，还包括下一代收发机的设计。