Main differences between Carrier aggregation and Dual Connectivity

•Dual Connectivity is a mode of operation where a a multiple Rx/Tx capable UE in RRC CONNECTED mode can be configured to utilize the radio resource of two distinct schedulers, located in two eNBs namely Master eNB and Secondary eNB connected via a non-ideal back-haul over the X2 interface.

•Carrier aggregation (CA) is designed to increase the data rate per user by configuring the mobile terminal to be simultaneous ly connected with multiple cells of the serving base station, which makes the mobile terminal, or user equipment (UE), operate at multiple frequencies at the same time.

1. In Carrier aggregation (CA) user traffic splits between carriers on MAC layer
2. In Dual Connectivity (DC) user traffic splits on PDCP layer
3. In DC you can have different RAT but with CA it’s the same RAT on both carriers.
4. CA allows a UE to simultaneous transmit and receive data on multiple component carriers from a single eNodeB
5. Dual Connectivity (DC) allows a UE to simultaneously transmit and receive data on multiple component carriers from two cell groups via master eNodeB (MN) and secondary eNodeB (SN) 2.
6. CA is for the scenarios where the backhaul between nodes is ideal, while DC is for non-ideal backhaul, e.g., relatively large delay between nodes.
7. CA and DC are not mutually exclusive; and they can be jointly implemented for the same UE in the case where there are multiple carriers in the (MCG) master cell group and multiple carriers in the (SCG)secondary cell group