Six Critical Challenges for 6G Wireless Systems.

A large number of papers are now appearing on sixth-generation (6G) wireless systems, covering different aspects, ranging from vision, architecture, applications, and technology breakthroughs. With cellular systems in mind, this paper presents six critical, yet fundamental challenges that must be overcome before development and deployment of 6G systems. These include: Opening the sub-terahertz (sub-THz) spectrum for increased bandwidths and the ability to utilize these bandwidths, pushing the limits of semiconductor technologies for operation within the sub-THz bands, transceiver design and architectures to realize the high peak data rates, and realizations of sub-millisecond latencies at the network-level to achieve the 6G key performance indicators. Additionally, since 6G systems will not be introduced in a green fields environment, backwards compatibility with existing systems is discussed. Where possible, we present practical solutions to realize the identified challenges.