BACKGROUND OF THE DISCLOSURE

Field of the Disclosure

The present invention relates to a wireless communication system, and more particularly, to a method for performing dual connectivity (DC) based handover in a wireless communication system and an apparatus supporting the same.

Related Art

In order to meet the demand for wireless data traffic, which has been increasing since the commercialization of a fourth-generation (4G) communication system, efforts are being made to develop an improved fifth-generation (5G) communication system or pre-5G communication system. For this reason, a 5G communication system or pre-5G communication system is referred to as a beyond-4G-network communication system or post-long-term evolution (LTE) system.

Meanwhile, in dual connectivity (DC) based handover, several issues can be considered. If the UE reports the measurement report when the serving cell is lower than target cell or a threshold, the MgNB is likely to be dropped before the role change. If the UE reports the measurement report when the target cell is higher than a threshold, the role change can be performed even the channel quality of PCell is better than PSCell. Also, there is no event which can compare the PCell and PSCell, currently. Therefore, a method for performing conditional role change in a dual connectivity and an apparatus supporting the same need to be proposed.

SUMMARY OF THE DISCLOSURE

One embodiment provides a method for performing, by a user equipment (UE), a role change between a primary cell and a secondary cell in a wireless communication system. The method may include: receiving a configuration and a condition for triggering the role change between the primary cell and the secondary cell; configuring a source cell as the primary cell and a target cell as the secondary cell; determining whether or not the condition is satisfied; and when it is determined that the condition is satisfied, configuring the target cell as the primary cell and the source cell as the secondary cell based on the configuration.

Another embodiment provides a user equipment (UE) performing a role change between a primary cell and a secondary cell in a wireless communication system. The UE may include: a transceiver; at least one processor; and at least one computer memory operably connectable to the at least one processor and storing instructions that, when executed, cause the at least one processor to perform operations comprising: receiving a configuration and a condition for triggering the role change between the primary cell and the secondary cell; configuring a source cell as the primary cell and a target cell as the secondary cell; determining whether or not the condition is satisfied; and when it is determined that the condition is satisfied, configuring the target cell as the primary cell and the source cell as the secondary cell based on the configuration.

Another embodiment provides a method for performing, by a base station, a role change between a primary cell and a secondary cell in a wireless communication system. The method include: transmitting a configuration and a condition for triggering the role change between the primary cell and the secondary cell, to a user equipment, wherein the configuration includes a first configuration and a second configuration, wherein the first configuration is a configuration for configuring a target cell as the secondary cell, and wherein the second configuration is a configuration for configuring a source cell as the secondary cell and the target cell as the primary cell; configuring the source cell as the primary cell and the target cell as the secondary cell based on the first configuration; and configuring the target cell as the primary cell and the source cell as the secondary cell based on the second configuration and the condition.

Signaling overhead can be reduced in the DC-based handover.

