LBT with adaptive threshold for coexistence of cellular and WLAN in unlicensed spectrum

Coexistence of cellular networks and wireless local area network (WLAN) in unlicensed spectrum will be a vital application scenario in the future 5G network. Listen-before-talk (LBT) is one of the mechanisms to ensure a fair coexistence among various radio access networks. In this paper, we present a LBT algorithm with an adaptive threshold jointly considering the diverse traffic load conditions of cellular networks and the quality of service (QoS) metrics of user equipment (UE). The transmission procedure of a cellular base station (BS) is modeled utilizing M/GI/1 queuing system via queuing theory. Then the BS control the clear channel assessment (CCA) threshold according to the queue length to adapt to the diverse traffic loads under the condition of QoS guarantee. Simulation results show that the proposed algorithm achieves significant performance gain of the cellular network under the coexistence scenario on the premise of tolerable sacrifices on WLAN performance.