Performance analysis of dual connectivity in control/user-plane split heterogeneous networks.

To ensure seamless mobility, logical separation between control plane and data plane has been evolved as a promising solution for the forthcoming fifth generation (5G) cellular networks. Here, macro-cells provide control coverage using a low frequency band signal, whereas small-cells provide high data rates to the mobile terminals (MTs) over high frequency band signals. While performing frequent handovers over small-cells, throughput perceived by an MT may fall below the requested data rate. To deal with the high data rate demand of the forthcoming 5G networks, recently dual connectivity (DC) technology has been proposed for long term evolution (LTE) networks in Release 12. However, analyzing the performance of DC in control/user-plane (C/U) split LTE heterogeneous networks is quite limited in the preceding literature. In this work, we propose an analytical framework to compare the performances of DC with hard handover in C/U split architecture in terms of system throughput and saturation probability, i.e., the probability that the total demand for resources exceeds the total capacity of the serving cells. Our proposed framework explicitly considers the data rate demands of the MTs, traffic arrival pattern and channel conditions. The analytical results have also been validated against simulation results. Our analyses reveal that the performance gain of DC over traditional hard handover is actually conditional on underlying traffic load density and call arrival rates.