As wireless networks continue to evolve, stringent latency and reliability requirements and highly dynamic channels expose fundamental limitations of gNB-centric massive multiple-input multiple-output (mMIMO) architectures, motivating a rethinking of the user equipment (UE) role. In response, the UE is transitioning from a passive transceiver into an active entity that directly contributes to system-level performance. In this context, this article examines the evolving role of the UE in mMIMO systems during the transition from fifth-generation (5G) to sixth-generation (6G), bridging third generation partnership project (3GPP) standardization, device implementation, and architectural innovation. Through a chronological review of 3GPP Releases 15 to 19, we highlight the progression of UE functionalities from basic channel state information (CSI) reporting to artificial intelligence (AI) and machine learning (ML)-based CSI enhancement and UE-initiated beam management. We further examine key implementation challenges, including multi-panel UE (MPUE) architectures, on-device intelligent processing, and energy-efficient operation, and then discuss corresponding architectural innovations under practical constraints. Using digital-twin-based evaluations, we validate the impact of emerging UE-centric functionalities, illustrating that UE-initiated beam reporting improves throughput in realistic mobility scenarios, while a multi-panel architecture enhances link robustness compared with a single-panel UE.

翻译：随着无线网络的持续演进，严苛的时延与可靠性要求以及高度动态的信道环境暴露了以基站为中心的大规模多输入多输出（mMIMO）架构的根本性局限，促使我们重新思考用户设备（UE）的角色。为此，用户设备正从被动收发器转变为直接贡献于系统性能的主动实体。在此背景下，本文探讨了从第五代（5G）向第六代（6G）过渡期间，用户设备在大规模MIMO系统中不断演变的角色，并桥接了第三代合作伙伴计划（3GPP）标准化、设备实现与架构创新。通过对3GPP第15版至第19版的时间顺序回顾，我们重点阐述了用户设备功能从基本信道状态信息（CSI）上报，到基于人工智能（AI）和机器学习（ML）的CSI增强，再到用户设备发起的波束管理的演进过程。我们进一步审视了关键的实现挑战，包括多面板用户设备（MPUE）架构、设备端智能处理以及高能效运行，随后讨论了实际约束下相应的架构创新。基于数字孪生的评估验证了新兴的以用户设备为中心的功能所带来的影响，结果表明：在实际移动场景中，用户设备发起的波束上报提升了吞吐量；而与单面板用户设备相比，多面板架构增强了链路鲁棒性。