Energy-Efficient Resource Allocation in Heterogeneous Small Cell Networks with WiFi Spectrum Sharing

In this paper, we investigate the dynamic subchannel and power allocation in licensed/unlicensed spectrum sharing heterogeneous small cell networks with incomplete channel state information (CSI). We explore the formulated problem using the Lyapunov optimization method by considering co-tier interference and cross-tier interference in both licensed and unlicensed spectrums. The constraints of the minimum user quality of service (QoS), the maximum transmit power limit and the unique of subchannel allocation are also considered to achieve the optimal power and subchannel allocation. Based on the framework of Lyapunov optimization, the problem of energy efficient (EE) optimization can be broken down into three subproblems. Two of which are linear and the rest can be solved by introducing Lagrangian function. The mathematical analysis and simulation results confirm that the proposed scheme can achieve a significant utility performance gain and the EE-delay tradeoff.