Patent ID: 9338705
Filing Date: 2016-05-10
CPC Classification: H04J,H04L,H04W

Claim Text:
1. A method for performing a handover at a user equipment (UE) in a wireless mobile communication system which supports carrier aggregation, the method comprising: transmitting, by the UE to a source base station, a measurement report for a target base station; receiving, by the UE from the source base station, a handover command message, wherein the handover command message contains allocation information of two or more Downlink Component Carriers (DL CCs) and two or more Uplink CCs (UL CCs) assigned by the target base station, each of the two or more UL CCs being paired with a respective DL CC, and wherein one of the two or more DL CCs is assigned as a specific DL CC; and transmitting, by the UE to the target base station, a random access preamble via a UL CC being paired with the specific DL CC among the two or more UL CCs.