An Optimal Channel Occupation Time Adjustment Method for LBE in Unlicensed Spectrum

Load Based Equipment (LBE) mechanism is a category of Listen-Before-Talk (LBT) protocol adopted by LTE to access unlicensed channels to realize fair coexistence between LTE and Wi-Fi networks. However, most LBE optimization methods fix Channel Occupation Time (COT) in LBE neglecting its influence on network throughput and fairness. In the paper, considering the influence, we propose an optimal COT adjustment method for the LBE mechanism to maximize the throughput of LTE while satisfying the LTE users data rate demands and ensuring the fairness coexistence between LTE and Wi-Fi networks. To this end, we first propose a method to separately calculate the throughput of LTE network and Wi-Fi network on the coexistence unlicensed spectrum considering the synchronous of LTE on licensed and unlicensed spectrum, and then utilize a virtual Wi-Fi network construction method to assure the used fairness criterion. Based on the aforementioned methods the problem of throughput maximization of LTE is formulated as a constrained non-linear optimization problem solved by an optimal algorithm. Simulation results prove our proposed throughput calculation method is valid, and then demonstrate the LBE mechanism using our proposed method optimizes the throughput of the SBS network and ensures fairness.