Joint licensed and unlicensed spectrum allocation for unlicensed LTE

When sharing the unlicensed band with Wi-Fi users in unlicensed LTE (U-LTE) systems, the most critical issue is how to guarantee the harmonious coexistence between the two systems. On the other hand, when sharing the licensed band with the micro base station (MBS) in the small cell base station (SBSs), the co-channel interference needs to be properly coordinated. To address these two issues, power control, licensed and unlicensed spectrum allocation are jointly considered at the SBS to maximize the spectrum efficiency while guaranteeing the QoS of small cell users (SUs) and at the same time providing fair resource sharing with Wi-Fi users. The convex optimization method is applied to design the optimal scheme. Then, numerical results are provided to verify the proposed scheme and demonstrate the tradeoff between the Wi-Fi performance and the achievable spectrum efficiency at the SBS.