Energy Efficient Resource Allocation in Small Cells with WiFi Unlicensed Bands Sharing

Unlicensed spectrum has long been considered a powerful candidate for addressing spectrum resource shortages. The emergence of small cells makes network coverage more seamless, switching, and a better user experience. This paper introduces small base station (SBS) to enable not only the information transmission on the WLAN unlicensed spectrum, but also the communication with connected terminals through the licensed spectrum. The energy efficiency (EE) in small cells with WiFi unlicensed band sharing is studied. We first build a two-layer network model containing small cells and macro cells. In particular, the subchannel allocation and power optimization problems are jointly studied using the alternative direction method of multipliers (ADMM) algorithm. Then, to obtain an optimization scheme, a radio resource scheduling strategy is proposed, taking into account Quality of Service (QoS) requirements, maximum transmit power, and same layer interference. The effectiveness and optimal solution of the method are shown by simulation results.