AI 中文总结
该研究针对5G MIMO扩展到中上限频段极端MIMO时的失效问题，梳理FR3频段特性与6G需求，明确四大挑战及各类架构的能效权衡，提出分布式孔径等技术路线以构建可部署的6G E-MIMO架构。
AI 中文摘要
中上限频段，特别是频率范围3（FR3）内的7-8 GHz频段，已成为广覆盖第六代（6G）蜂窝网络的主要候选频谱。其更短的波长可在现有5G基站面板的物理孔径内集成数百个天线单元，原则上，由此产生的孔径增益可补偿增加的路径损耗，支持256个或更多天线端口的极端MIMO（E-MIMO），同时复用现有基站站点。但实际上，简单将5G新空口（NR）架构从数十个端口扩展到数百个端口会遇到根本性的系统级限制。本文确定了5G式MIMO扩展失效的环节，并制定了实用中上限频段E-MIMO的研究路线图。首先回顾FR3频谱的演进、其传播与信道特性以及新兴的6G系统需求；接着将主要挑战归为四个耦合领域：维持所有物理信道和协议状态下的有效覆盖、实现宽带高能效的射频器件与无线电单元、开发新型低功耗阵列与波束成形架构、以可管理的探测与反馈开销获取足够精细的信道状态信息；代表性系统研究阐明了用户特定数据传输与公共或信道获取信号之间的覆盖不对称，以及全数字、混合、三混合、动态超表面和流体天线架构之间的频谱与能效权衡；最后讨论分布式孔径、集成感知、人工智能辅助信道获取和环境感知操作如何将固定孔径扩展转化为可部署的6G E-MIMO架构。
英文摘要
The upper-mid band, particularly the 7-8 GHz range within frequency range 3 (FR3), has emerged as a leading spectrum candidate for wide-area sixth-generation (6G) cellular networks. Its shorter wavelength enables hundreds of antenna elements to be integrated within the physical aperture of an existing 5G base-station panel. In principle, the resulting aperture gain can compensate for the increased path loss and enable extreme MIMO (E-MIMO) with 256 or more antenna ports while reusing current cell sites. In practice, however, simply scaling the 5G New Radio (NR) architecture from tens to hundreds of ports encounters fundamental system-level limitations. This paper identifies where 5G-style MIMO scaling breaks and develops a research roadmap for practical upper-mid-band E-MIMO. We first review the evolution of FR3 spectrum, its propagation and channel characteristics, and the emerging 6G system requirements. We then organize the principal challenges into four coupled areas: maintaining effective coverage across all physical channels and protocol states; implementing wideband, energy-efficient RF devices and radio units; developing new low-power array and beamforming architectures; and acquiring sufficiently refined channel state information with manageable sounding and feedback overhead. Representative system studies illustrate the coverage asymmetry between user-specific data transmission and common or channel-acquisition signals, as well as the spectral- and energy-efficiency tradeoffs among fully digital, hybrid, tri-hybrid, dynamic-metasurface, and fluid-antenna architectures. Finally, we discuss how distributed apertures, integrated sensing, AI-assisted channel acquisition, and environment-aware operation can transform fixed-aperture scaling into a deployable 6G E-MIMO architecture.
Comments23 pages, 9 figures
