Inter-eNB Flow Control for Heterogeneous Networks with Dual Connectivity

In scenarios where the macro and small cells are deployed at different carrier frequencies, dual connectivity (DC) is a promising technique to enable user equipments (UEs) to receive data from a macro cell and a small cell eNodeBs (eNBs) simultaneously, therefore opportunities to be served at higher data rates. In this paper we focus on the case that the macro and small cell eNBs are inter-connected with traditional backhaul connections characterized by certain latency, assuming independent radio resource management (RRM) functionalities residing in each eNB. In order to fully harvest the gain provided by DC, an efficient flow control of data between the involved macro and small cell eNBs is proposed. It is demonstrated how proper configuration of the proposed flow 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 in the small cell eNB. The simulation results show that the performance of DC over traditional backhaul connections is close to that achievable with carrier aggregation (CA) assuming virtually zero-latency fronthaul connections, and in any case it is significantly higher than the performance without DC