Terahertz Communications for Massive Connectivity and Security in 6G and Beyond Era

Terahertz (THz) communications (THzCom) has experienced a meteoric rise of interest due to its benefits for ultra-high data rate transmission in the sixth generation (6G) and beyond era. Despite this, the research on exploring the potential of THzCom for other performance targets anticipated by 6G, including massive connectivity and security, is still in its infancy. In this article, we start with briefly describing the unique peculiarities of THz channels and then discuss theoretical frameworks to facilitate the analysis and design of THz transmission for achieving massive connectivity and security. Then we discuss promising spectrum management strategies, including the exploration of multiple THz transmission windows and frequency reuse with multiplexing and signal processing, to substantially increase the number of supported users and identify to-be-tackled challenges. We further present important research directions based on the principles of physical layer security, such as new spectrum allocation policies and beamforming algorithms, to fight against eavesdropping in THzCom systems, ushering in secure THzCom systems.

Introduction

Our society is in the era of mobile wireless Internet with explosive big data. While the fifth generation (5G) wireless systems are being deployed worldwide, the telecommunications community has identified emerging use cases and technologies needed for an intelligent information society in the 2030s [1], most of which have quality of service (QoS) requirements far beyond what 5G can offer. For example, as a promising technology allowing doctors to perform remote surgeries, holographic telepresence often requires vast amounts of data (e.g., holographic images from multiple viewpoints) to be instantly communicated at data rates of several hundred gigabits per second or beyond 1Tb/s[1], which is 10–100 times higher than the maximum data rate of 5G. To satisfy such unprecedented QoS requirements, the global research community and industry have reached a consensus to exploit frequencies at the terahertz (THz) band (0.1-10 THz) for the sixth generation (6G) and beyond wireless systems [2]. In particular, the relatively low THz band (e.g., 0.1-0.3 THz) is envisioned to be regulated for use in 6G [3], while the higher THz band (e.g., 0.3-1 THz) is anticipated to be adopted in beyond 6G.