Coexistence Performance Analysis of LAA Based on Release 13

In March 2016, a new protocol called licensed-assisted access (LAA) has been embodied in Release 13 (Rel-13) for Long-Term Evolution (LTE) to operate on unlicensed spectrum and interwork with Wi-Fi. The relevant standards clarify the channel access procedures and contention window (CW) adjustment procedures for LAA. In a long period of time, the coexistence performance of LAA with other technologies, especially Wi-Fi, receives people's attention and a lot of work has been done based on simulation. In this paper, we focus on the mathematical calculations and provide an analytical model of LAA defined in Rel-13, considering the features such as variable CW sizes and different channel access priority classes. The influence of LTE frame structure is also taken into account. The analytical model provides an effective method of computing the saturation throughput of different coexistence scenarios, where finite number of stations share an unlicensed ideal channel. The effectiveness of proposed model is evaluated through simulation results. We also explore how the system parameters influence the numerical results for the further study on the efficiency improvement of LAA.