An energy-efficient resource allocation for optimal downlink coverage in heterogeneous wireless cellular networks

This paper investigates downlink coverage maximisation in a heterogeneous wireless cellular network (HWCN) taking into account various indoor and outdoor propagation models. By using stochastic geometry modeling of multi-tier cells, the coverage probability of the practical HWCN is firstly derived characterising the impacts of cell density allocation, power allocation at cells, building infrastructures and transmission environment. It is interestingly observed that the increase of cell densities may not result in a higher coverage but causes a higher total power consumption. The coverage optimisation problem is therefore formulated aiming at maximising the coverage probability subject to the constraints on the power available in the HWCN. Specifically, an heuristic cell density allocation algorithm is proposed for the cell allocation at multiple tiers within various propagation models. The proposed scheme is shown to not only achieve a higher coverage region of up to 25% but also save 20% of power consumption when compared to the equal resource allocation mechanism.