System architecture and coexistence evaluation of licensed-assisted access LTE with IEEE 802.11

Licensed-assisted access (LAA) is a new operation mode of Long-Term Evolution (LTE) in the unlicensed spectrum currently under study in the 3GPP standardization forum. In order to coexist with Wi-Fi, some of the new functionalities required of LAA LTE include a mechanism for clear channel assessment based on listen-before-talk (LBT), discontinuous transmission on a carrier with limited maximum transmission duration, and dynamic frequency selection (DFS) for radar avoidance in certain frequency bands. This paper presents a detailed overview of the impact of unlicensed spectrum operation on the LTE physical layer architecture, such as downlink physical channel design, scheduling, and radio resource management. System-level simulation results are then presented for indoor and outdoor scenarios, and show that fair coexistence between LAA and Wi-Fi can be achieved and that deployment of LAA can provide a boost in Wi-Fi performance.