Network Densification and Path-Loss Models Versus UDN Performance—A Unified Approach

Ultra-dense network (UDN) is one of the most important techniques to support massive number of different types of user equipments (UEs). It is essential to understand the impact of densification on various system performance metrics in future cellular networks. Two contradictory conclusions were made from the existing research works. Some works indicated that the network densification has reached its upper limit and deploying more UEs may only reduce UDN performance; whereas the others claimed that more UEs can still be supported by deploying more small cell base stations (SBSs). The existence of above different conclusions is due mainly to the difficulties to find an effective means to take into account different path loss models in UDNs. In this paper, we aim to propose a unified analytical approach, which is effective to simplify UDN performance analysis based on different path loss models with a low computation complexity. Using the proposed approach with idle mode of SBSs enabled, we can identify the impact of the densities of SBSs and UEs on various performance metrics, i.e., coverage probability and average area spectral efficiency (ASE). The conclusions will be supported by the analytical and simulation results verifying the effectiveness of the proposed unified analytical approach.