Analysis of Dual Connectivity for Downlink Access in 5G Heterogeneous Network

Dual-Connectivity architecture allows each user's equipment (UE) to simultaneously communicate with two kinds of serving base stations (BSs) via two different radiointerfaces. Dual-Connectivity paradigm emerges as a promising solution to boost system capacity in fifth-generation heterogeneous network (HetNet), deploying multiple kinds of BSs, such as Femto BSs (FBSs), Pico BSs (PBSs) and Macro BSs (MBSs). In this paper, a comprehensive study of Dual-Connectivity in the downlink HetNet is analyzed via the framework of stochastic geometry, where the deployments of theBSs aremodeled asmutually independent homogeneous Poisson point processes. In the conventional Dual-Connectivity, only the combination ofMBS and SBS is available to access. In this paper, we consider that eachUEcan be simultaneously associated with any two types of BSs. The analysis is divided into two parts. We first derive the association probabilities of different combinations for Dual-Connectivity and then evaluate the average downlink throughput with the help of the association probabilities and the distance distributions to the serving BS. Moreover, we analyze the impact of the relative density of FBSs (or PBSs) on the association probabilities of different cases. Also, we compare the average downlink throughput of our considered Dual-Connectivity with those of conventional Dual-Connectivity and single association. Numerical results prove the validity of the theoretical analyses and demonstrate that our considered Dual-Connectivity owns superior performance on the throughput in HetNet, especially in the dense deployed SBS HetNet.