The initial 6G networks will likely operate in the upper mid-band (7-24 GHz), which has decent propagation conditions but underwhelming new spectrum availability. In this paper, we explore whether we can anyway reach the ambitious 6G performance goals by evolving the multiple-input multiple-output (MIMO) technology from being massive to gigantic. We describe how many antennas are needed and can realistically be deployed, and what the peak user rate and degrees-of-freedom (DOF) can become. We further suggest a new deployment strategy that enables the utilization of radiative near-field effects in these bands for precise beamfocusing, localization, and sensing from a single base station site. We also identify five open research challenges that must be overcome to efficiently use gigantic MIMO dimensions in 6G from hardware, cost, and algorithmic perspectives.

翻译：初代6G网络预计将运行于高中频段（7-24 GHz），该频段虽具备良好的传播条件，但新增频谱资源却令人失望。本文探讨了如何通过将多输入多输出（MIMO）技术从大规模演进至巨型规模，来达成雄心勃勃的6G性能目标。我们阐述了所需天线的数量与实际部署可行性，并分析了可实现的峰值用户速率与自由度（DOF）。进一步地，我们提出了一种新型部署策略，该策略能够利用这些频段的辐射近场效应，实现单基站站点的精确波束聚焦、定位与感知功能。此外，我们从硬件、成本及算法角度，指出了必须克服的五大开放性研究挑战，以高效利用6G中的巨型MIMO维度。