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Dual Connectivity Introduction

Dual Connectivity allows the phone to be connected simulatenously to two radio base stations.

What can be achievied with DC?

The phone may send and received data from both nodes at the same time. User plane tranmission is aggregated (Figure 1).
Figure 1 User Plane aggregation in Dual Connectivity

It shall be mentioned that two nodes in the RAN shall be connected directly. What is more one node in DC relation will be called Master Node (MN) and the other one will be called Secondary Node (SN). The signalling connection is anchored in the MN. In a one of the cases this will allow to have User Plane and Control Plane separation as it is shown in Figure2.

Figure 2 User Plane and Control Plane separation

One other case is when the direction of transmission could be separated. The transmission in the Uplink direction (UL) can be done through SN and tranmission in Downlink direction (DL) can be done through MN. This is depicted in Figure 3

Figure 3 UL/DL separation
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