While the deployment of 5G cellular systems will continue well into the next decade, much interest is already being generated toward technologies that will underlie its successor, 6G. Undeniably, 5G will have a transformative impact on the way we live and communicate, but it is still far away from supporting the Internet of Everything, where upward of 1 million devices/km ³ (both terrestrial and aerial) will require ubiquitous, reliable, low-latency connectivity. This article looks at some of the fundamental problems that pertain to key physical layer enablers for 6G. This includes highlighting challenges related to intelligent reflecting surfaces, cell-free massive MIMO, and THz communications. Our analysis covers theoretical modeling challenges, hardware implementation issues, and scalability, among others. The article concludes by delineating the critical role of signal processing in the new era of wireless communications.

中文翻译：

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通往6G之路：通信工程师面临的十个物理层挑战

尽管5G蜂窝系统的部署将持续到下个十年，但已经引起了人们对其基础6G的技术的极大兴趣。不可否认，5G将对我们的生活和通信方式产生革命性的影响，但它离支持万物互联仍然遥遥无期，万物互联/公里³百万 （地面和空中）都将需要无处不在，可靠，低延迟的连接。本文着眼于与6G关键物理层支持器有关的一些基本问题。这包括与智能反射面，无单元大规模MIMO和THz通信相关的突出挑战。我们的分析包括理论建模挑战，硬件实现问题和可伸缩性等。文章最后总结了信号处理在无线通信新时代中的关键作用。