The Road Towards 6G: A Comprehensive Survey

TL;DR

This comprehensive survey explores the motivations, requirements, potential technologies, and future outlook of 6G mobile communication systems, aiming to guide research and development efforts towards the next generation of wireless technology.

Contribution

It provides an in-depth overview of 6G's drivers, use cases, technical requirements, current research efforts, and potential enabling technologies, offering a roadmap for future development.

Findings

6G is driven by explosive mobile traffic growth and new use cases.

6G's key performance indicators are significantly more demanding than 5G.

Multiple emerging technologies are identified as potential enablers for 6G.

Abstract

As of today, the fifth generation (5G) mobile communication system has been rolled out in many countries and the number of 5G subscribers already reaches a very large scale. It is time for academia and industry to shift their attention towards the next generation. At this crossroad, an overview of the current state of the art and a vision of future communications are definitely of interest. This article thus aims to provide a comprehensive survey to draw a picture of the sixth generation (6G) system in terms of drivers, use cases, usage scenarios, requirements, key performance indicators (KPIs), architecture, and enabling technologies. First, we attempt to answer the question of "Is there any need for 6G?" by shedding light on its key driving factors, in which we predict the explosive growth of mobile traffic until 2030, and envision potential use cases and usage scenarios. Second, the technical requirements of 6G are discussed and compared with those of 5G with respect to a set of KPIs in a quantitative manner. Third, the state-of-the-art 6G research efforts and activities from representative institutions and countries are summarized, and a tentative roadmap of definition, specification, standardization, and regulation is projected. Then, we identify a dozen of potential technologies and introduce their principles, advantages, challenges, and open research issues. Finally, the conclusions are drawn to paint a picture of "What 6G may look like?". This survey is intended to serve as an enlightening guideline to spur interests and further investigations for subsequent research and development of 6G communications systems.