Energy-efficient base station deployment in heterogeneous cellular network with QoS constraint

We investigate the energy efficiency in the downlink of a two-tier heterogeneous cellular network with quality of service consideration. By modeling the distributions of the macrocell and small cell base stations follow two independent homogeneous Poisson point processes, we derive the analytical expressions of the mean achievable rate and the energy efficiency with the assumption that a mobile user connects to the closest BS. In addition, we evaluate the energy efficiency subject to a constraint of the blocking probability. Considering the dynamic variation of the traffic load, we use the numerical results to show that the optimum value of energy efficiency can be reached at determined deployment densities of the macrocells and the small cells, and the blocking probability has a dramatic impact on the optimal base station deployment.