A Field Trial of Unlicensed LTE (U-LTE) in 5.8 GHz Band

Abstract

To alleviate network congestion and improve the spectrum efficiency, it is natural to consider operating Long Term Evolution (LTE) on unlicensed spectrum, which is called Unlicensed LTE (U-LTE). In order to get practical experience with U-LTE, NTT DOCOMO and Huawei built up a U-LTE trial system operating over bandwidth of 20MHz in 5.8 GHz unlicensed bands and a field trial was conducted in 2014. The U-LTE system operated in real time and was field tested in typical indoor environments. In this paper, we report the field trial results for both U- LTE and Wi-Fi systems. Our objective is twofold: firstly, coverage and capacity performance in single cell are presented to confirm the potential effectiveness of using U-LTE in the operator network. Secondly, the intra-Radio-Access-Technology (RAT) coexistence performance conducted in different interference scenarios disclosed a challenging problem, i.e., the straightforward introduction of LTE into the unlicensed spectrum is not recommended and interference avoidance technology is necessary in U-LTE.