Performance analysis of spatially distributed LTE-U/NR-U and Wi-Fi networks: An analytical model for coexistence study

Abstract

To access an unlicensed channel, Wi-Fi follows the Listen Before Talk (LBT) mechanism, whereas LTE-U (and future New Radio in Unlicensed (NR-U) Patriciello et al., 2020; Lagen et al., 2019) adopts the ON–OFF duty-cycled mechanism to fairly share the channel with Wi-Fi. These different mechanisms result in quite different performance for Wi-Fi and LTE-U/NR-U based on their relative deployment and density in the environment. In this work, we present an analytical model for the characterization of achievable throughputs of Wi-Fi and LTE-U networks in spatially distributed scenarios with downlink-prevalent traffic. The proposed model is used to study how LTE-U and Wi-Fi coexist with each other in spatially distributed scenarios. Our extensive simulation results show that it is a reliable model for estimating the throughput of both Wi-Fi and LTE-U in a spatially distributed deployment. The impact of various network parameters such as energy detection and carrier sense threshold on Wi-Fi and LTE-U coexistence is explored as a byproduct and corroborated via a National Instrument experimental test bed. Our model gives very high accuracy in throughput estimation and the mean normalized error is less than 3% for a 80-node scenario in which 50% of nodes belong to each of Wi-Fi and LTE-U network. The analytical model is also used to conduct coexistence studies of LTE-U and Wi-Fi. © 2021