LTE in the Unlicensed Band: Overview, Challenges, and Opportunities

One critical challenge with wireless data service provisioning is how to exploit the limited spectrum resources efficiently to support the dramatically growing traffic. To address this challenge, the FCC has released an additional 295 MHz bandwidth in the 5G U-NII bands for wireless communications. How to make full use of this unlicensed band has recently attracted considerable attention from academia and cellular operators worldwide. The 3GPP has also initiated a study group to investigate the coexistence of LTE and other access technologies in this unlicensed band. In this article, we provide an overview of various technical issues on LTE-U and identify several open research challenges and opportunities related to LTE-U design.