Exploiting Dual Connectivity in Heterogeneous Cellular Networks

Abstract: We consider network utility maximization problems over heterogeneous cellular networks (HetNets) that permit dual connectivity. Dual connectivity (DC) is a feature that targets emerging practical HetNet deployments that will comprise of non-ideal (higher latency) connections between transmission nodes, and has been recently introduced to the LTE-Advanced standard. DC allows for a user to be simultaneously served by a macro node as well as one other (typically micro or pico) node and requires relatively coarser level coordination among serving nodes. For such a DC enabled HetNet we comprehensively analyze the problem of determining an optimal user association, where in any feasible association each user can be associated with (i.e., configured to receive data from) any one macro node (in a given set of macro nodes) and any one pico node that lies in the chosen macro node's coverage area. We consider the weighted sum rate system utility subject to per-user maximum and minimum rate constraints, as well as the proportional fairness (PF) system utility. For both utility choices we construct approximation algorithms and establish their respective approximation guarantees. We then validate the performance of our algorithms via numerical results.