Nearest Distance Based Downlink Rate Modeling in Hyper-dense Heterogeneous Wireless Cell Networks

Different kinds of low transmit power, flexible cell extension and hyper dense base stations (BSs) overlaying on the well established macro cells, forming the hyper-dense multilayer heterogeneous wireless cell networks (HetNets), where the BSs in each tier are characterized by the differences in BSs transmit power, path loss exponent, tier-biasing factor and BSs spatial density, is the promising technology for 5th generation mobile networks and to support hot spots and cell edge coverage. The HetNets downlink rate modeling is one of the key and challenge problems for the random deployment characteristics of BSs in lower layer. In this paper, a three tier HetNets, which includes macro tier, Pico tier and Femto tier, is first modeled with the spatial point process in stochastic geometry theory; then, considering the BSs low transmit power, flexible cell extension and hyper BSs spatial density, a tractable downlink rate model based on the nearest distance and bias accepted factor is proposed, which adopt stochastic geometry theory and is easy to compute; last, the proposed downlink rate model is validated by numerical examples to confirm that the flexible cell extension BSs deployment in complex high traffic area with different path loss exponent is an effective scheme to improve quality of service.