Dual connectivity for LTE-advanced heterogeneous networks

Dual connectivity (DC) allows user equipments(UEs) to receive data simultaneously from different eNodeBs(eNBs) in order to boost the performance in aheterogeneous network with dedicated carrier deployment.Yet, how to efficiently operate with DC opens a number ofresearch questions. In this paper we focus on the casewhere a macro and a small cell eNBs are inter-connectedwith traditional backhaul links characterized by certainlatency, assuming independent radio resource management(RRM) functionalities residing in each eNB. In order tofully harvest the gain provided by DC, an efficient flowcontrol of data between the involved macro and small celleNBs is proposed. Moreover, guidelines for the main performancedetermining RRM algorithms such as UE cellassociation and packet scheduling are also presented. It isdemonstrated how proper configuration of the proposedflow control algorithm offers efficient trade-offs between reducing the probability that one of the eNBs involved in the DC runs out of data and limiting the buffering time.Simulation results show that the performance of DC over traditional backhaul connections is close to that achievable with inter-site carrier aggregation (CA) and virtually zerolatency fronthaul connections, and in any case it is significantlyhigher compared to the case without DC.Keywords: Dual connectivity Heterogeneous network LTE-advanced Radio resource management Performance evaluatio