Achieving 3GPP Fairness for LTE-U and WiFi Coexisting Networks in Unlicensed Spectrum

One of the major challenges for the development of next generation mobile communications is how to meet the growing demand of high data rate with the increasingly scarce spectrum resources. In the past a few years, introducing Long Term Evolution (LTE) into the unlicensed spectrum (LTE-U) has attracted extensive attention, where a key question is how to achieve fair coexistence between LTE-U and WiFi under the unlicensed spectrum. In this paper, we study how to adaptively tune the duty cycle to maintain 3GPP fairness between LTE-U and WiFi with the LTE-U duty-cycling mechanism. Based on a unified analytical model, explicit expression of the optimal duty cycle is derived for achieving 3GPP fairness. The analysis is well verified by simulation results, which provides practical insights on LTE/WiFi coexistence issue.