Optimising coverage efficiency in heterogeneous wireless cellular networks

Abstract

In this paper, we first propose an analytical model for investigating the impacts of power allocation (PA) and cell density allocation (CDA) on coverage efficiency (CE) of heterogeneous wireless cellular networks (HWCNs) under limited resources in various propagation environment. It is shown that the interference among cells that belong to different tiers is reduced significantly in a higher path loss environment and results in a higher coverage. In addition, the overall network coverage of the HWCN can be further extended with the deployment of a higher cell density in a more lossy environment. This accordingly leads us to develop an optimization problem (OP) to maximize the CE by optimizing the PA and CDA for a downlink HWCN under the constraint of limited power at cells and total power available in the network. In particular, we propose a two-stage approach for solving the OP to sequentially obtain the heuristic value of the CDA and PA due to complicated objective function along with various involved parameters in the practical HWCN. Numerical results reveal that the coverage obtained by the heuristic solution at the first-stage is significantly improved with a lower power than the conventional approach. Furthermore, an enhanced overall CE is achieved for all cases of the power constraint when applying fully two stages in our proposed algorithm.