Future Trends in Cellular Infrastructure and Radio Technology for Sustainable Networks

Wireless standards and radio requirements are evolving as the roll-out of 5G, emergence of open radio access networks (O-RAN), and early investigation of 6G are progressing forward. Particularly, multi-band macro-cell frequency-division duplexing (FDD) radio heads, massive multiple-input multiple-output (MIMO) time-division duplexing (TDD) radio units, and emerging frequency bands beyond sub-6 GHz present a unique challenge to the industry, striving for higher energy efficiency and capacity. This paper aims to provide an overview and discuss the future directions for research in radio architectures, radio frequency (RF) power amplifiers (PA), and digital transformation, leveraging machine learning and linearization techniques for cellular infrastructure.