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

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.