Femto-station allocation for green hierarchical cellular network

We propose a green femto-station (FS) assignment algorithm for a hierarchical cellular network. It is assumed that the cellular network consists of one macro station, several femto stations equipped with the renewable energy source, and several battery-driven mobile stations. We also assume that the FS has limited incoming energy, and the occurrence and the duration of the mobile station´s downlink transmission request is a stochastic process. To improve the service quality, i.e., reduce the probability of the FSs´ service outage, a stationary FS assignment schedule is obtained for certain period by solving a combinatorial optimization problem. First we construct a Markov chain model to estimate the service outage probability, i.e., rejection probability, for given FS assignment schedule; based on the estimation model, we then propose a low-complexity local search algorithm, which balances the computation complexity and the performance, to obtain the local optimal FS assignment schedule efficiently. Simulation results are provided to demonstrate the superior performance of the proposed techniques over the traditional methods.