Joint resource allocation over licensed and unlicensed spectrum in U-LTE networks

By sharing unlicensed spectrum with Wi-Fi networks, unlicensed LTE (U-LTE) is one of the promising approaches to further improve LTE network throughput. However, the problem of coexistence with Wi-Fi networks is one of the main challenges of U-LTE technology. In this work, we study joint resource allocation for LTE over the legacy licensed spectrum and the unlicensed spectrum to maximize the benefit of U-LTE in a multi-cell scenario. Specifically, we formulate a mixed-integer power-channel-time allocation problem aiming at maximizing the network throughput, with the constraints of protecting the coexisting Wi-Fi networks and satisfying hardware limitation on bandwidth occupancy of user equipments (UEs), while guaranteeing per UE's throughput. To solve the resource allocation problem, we exploit the delay column generation approach to decompose the original optimization problem and then propose a novel algorithm based on Karush-Kuhn-Tucker conditions. Furthermore, we analyze the gap between the proposed algorithm and the optimal solution. Simulation results show the advantage of the proposed algorithm in terms of the network throughput and convergence speed.