NR-U and Wi-Fi Spectrum Sharing: Design Challenges and Solutions

This work provides an in-depth analysis of theListen-Before-Talk (LBT) procedures that cellular technologiesmust adhere to for operation in the unlicensed spectrum. In par-ticular, we provide detailed insights into the 5G New Radio Un-licensed (NR-U) standalone design according to the latest 3GPPstandard-compliant Type 1 Channel Access Procedure (CAP).We highlight some of the challenges and propose improvedmechanisms for channel access. We carry out the performanceevaluation study using a full-stack end-to-end network simulator.We built a realistic 3GPP-compliant coexistence scenario in which5G NR-U and Wi-Fi networks operate indoors in the unlicensedsub-7 GHz bands, and the users of both operators run eXtendedReality applications. Through an extensive evaluation study, weanalyse the interplay between the NR-U numerologies and theCAPs used in shared channel access and evaluate their commonimpact on the end-to-end performance of both technologiesby considering various quality of service metrics. The resultsreveal some of the main pitfalls of the standard-compliant LBTprocedure defined by 3GPP in TS 37.213 and demonstrate theclear advantages of our proposed solutions. Our work providesvaluable insights and solutions and sets the groundwork forfuture research by providing a pioneer open-source networksimulation platform to simulate the coexistence scenarios withNR-U standalone employing standard-compliant Type 1 CAP.