Analysis of 5G NR base stations offloading by means of NR-U technology

Fifth generation millimeter wave New Radio (NR) base stations (BS) are expected to be deployed in areas with extremely high and drastically fluctuating traffic demands resulting in frequent QoS (Quality of Service) violations in terms of provided rate at the access interface, especially, during busy hour conditions. As one of the measures to combat congestion, 3GPP (3rd Generation Partnership Project) considers the NR-U (NR-Unlicensed) technology, which allows to use the unlicensed frequency spectrum, for example, 60 GHz, on the BS in addition to the licensed spectrum. In this case, a session that cannot be served in the licensed spectrum due to lack of resources can be redirected to the unlicensed spectrum where competition for resources with WiGig technology subscribers takes place. The aim of this study is to evaluate the QoS (quality of service) parameters in an area characterized by a certain density of NR and WiGig users, where NR users can use NR-U technology if their rate requirements are met. The studied metric is the NR session loss probability and the achievable transmission rate in the unlicensed frequency spectrum. The performed numerical study shows that in addition to the density of NR and WiGig UE, the studied characteristics are influenced by the size of the contention window, the density of blockers, and the minimum required rate. The presented numerical results allow one to conclude that the approach under consideration can significantly increase the attainable data rate of user sessions but this requires dense deployments of NR technology.