LTE in the unlicensed spectrum: A novel coexistence analysis with WLAN systems

In this paper, we consider the operation of the Long Term Evolution (LTE) systems in the unlicensed spectrum. Given the lack of the exclusive use of the spectrum, the operation in the unlicensed band is fundamentally limited by interference from other technologies using the same frequency band. By noting that the unlicensed spectrum is heavily used by Wireless Local Area Networks (WLAN), here we focus on the mutual effect between LTE and WLAN when they coexist. For this, we developed a novel inter-system interference analysis technique based on the continuum field approximation and spiral representation, which improves the accuracy of the previous approaches and is applicable to both large-scale and small-scale networks. To this end, we quantify the effect of inter-system interference when the LTE and WLAN systems operate in the same unlicensed spectrum.