发表机构
Spark; Qualcomm; NVIDIA; Samsung; Nokia（Spark; 高通; 英伟达; 三星; 诺基亚）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文评估无线物理层技术成熟度，指出链路级改进增益有限，而大规模MIMO、分布式MIMO及AI/ML驱动的空间处理和CSI获取是未来主要突破方向。
AI 中文摘要
无线物理（PHY）层通过调制、编码、波形和多输入多输出（MIMO）传输方面的进步，实现了连续几代蜂窝系统的发展。本文评估了这些技术是否正接近成熟，以及在哪里仍有可能实现大幅度的进一步增益。现场测量和定量评估表明，许多链路级改进，包括星座整形、信道编码演进、降低复杂度的接收机和波形增强，仍然有价值，但通常提供的增益有限，必须与实现复杂度和开销进行权衡。相比之下，大规模MIMO和分布式MIMO通过增加可用空间信道的数量和质量，提供了更具可扩展性的系统级机会。其有效性依赖于时分双工互易性以实现可扩展的信道状态信息（CSI）获取，而实际限制包括校准、导频复用、信道老化、来自小区边缘用户的弱导频接收，以及相干分布式操作的传输网络和同步要求。人工智能和机器学习（AI/ML）为进一步的PHY层创新提供了补充机会。因此，物理层并未消亡；其最重要的进展将来自可部署的空间处理和CSI获取，并辅以有针对性的链路级和基于AI/ML的改进。
英文摘要
The wireless physical (PHY) layer has enabled successive generations of cellular systems through advances in modulation, coding, waveforms, and multiple-input multiple-output (MIMO) transmission. This article assesses whether these techniques are now approaching maturity and where substantial further gains remain possible. Field measurements and quantitative evaluations indicate that many link-level refinements, including constellation shaping, channel-code evolution, reduced-complexity receivers, and waveform enhancements, remain valuable but typically provide bounded gains that must be balanced against implementation complexity and overhead. In contrast, massive MIMO and distributed MIMO offer a more scalable system-level opportunity by increasing the number and quality of usable spatial channels. Their effectiveness relies on time-division duplex reciprocity for scalable channel state information (CSI) acquisition, while practical limitations include calibration, pilot reuse, channel aging, weak pilot reception from cell-edge users, and the fronthaul and synchronization requirements of coherent distributed operation. Artificial intelligence and machine learning (AI/ML) provide complementary opportunities for further PHY layer innovations. The PHY layer is therefore not dead; its most consequential advances will come from deployable spatial processing and CSI acquisition, complemented by targeted link-level and AI/ML-based refinements.
Comments18 pages, 23 figures, 5 tables
