For heterogeneous cellular network based on energy harvesting

due to randomness of the energy and channel state

the applicability of the offline power allocation algorithm can only obtain the theoretical optimal value

therefore

an online power allocation algorithm is proposed.Base station controller uses energy checking algorithm to choose the small base station

which satisfies the activation condition at the beginning of each time slot for the proposed algorithm.Then

a two layer iterative (TLI) algorithm based on the Lagrange multiplier method is proposed to maximize the system energy efficiency of the chosen small base stations practically in each time slot.Simulation results show that the proposed algorithm can provide high energy efficiency for dense heterogeneous networks when the activation condition of the small base station is satisfied.The proposed algorithm is suitable for the network with unpredictability of the channel state information and energy state information.