A method for a User Equipment, UE, operating in a wireless communication system, the method comprising: configuring, by the UE, a first cell belonging to a first Base Station, BS,, wherein the first cell is configured with Transmission Time Interval, TTI, bundling enabled, and wherein the first cell is a cell with configured uplink belonging to the first BS; receiving, by the UE from a Evolved Universal mobile telecommunication system Terrestrial Radio Access Network, E-UTRAN, a Radio Resource Control, RRC, connection reconfiguration message for configuring a second cell with configured uplink belonging to a second BS; and configuring, by the UE, the second cell with configured uplink belonging to the second BS, the method characterized in that: checking whether the first BS and the second BS are same or not, wherein, when the first BS and the second BS are same and when the RRC connection reconfiguration message is considered as invalid, the UE initiates RRC connection reconfiguration procedure and informs the first BS of failure for the configuring the second cell, wherein, when the first BS and the second BS are same and when the RRC connection reconfiguration message is considered as valid, the UE autonomously disables the TTI bundling for the first BS, informs the first BS of disabling the TTI bundling, and configures the second cell for the first BS, and wherein, when the first BS and the second BS are different, the UE keeps using the TTI bundling for the first BS and configures the second cell for the second BS. configuring, by the UE, a first cell belonging to a first Base Station, BS,, wherein the first cell is configured with Transmission Time Interval, TTI, bundling enabled, and wherein the first cell is a cell with configured uplink belonging to the first BS; receiving, by the UE from a Evolved Universal mobile telecommunication system Terrestrial Radio Access Network, E-UTRAN, a Radio Resource Control, RRC, connection reconfiguration message for configuring a second cell with configured uplink belonging to a second BS; and configuring, by the UE, the second cell with configured uplink belonging to the second BS, the method characterized in that: checking whether the first BS and the second BS are same or not, wherein, when the first BS and the second BS are same and when the RRC connection reconfiguration message is considered as invalid, the UE initiates RRC connection reconfiguration procedure and informs the first BS of failure for the configuring the second cell, wherein, when the first BS and the second BS are same and when the RRC connection reconfiguration message is considered as valid, the UE autonomously disables the TTI bundling for the first BS, informs the first BS of disabling the TTI bundling, and configures the second cell for the first BS, and wherein, when the first BS and the second BS are different, the UE keeps using the TTI bundling for the first BS and configures the second cell for the second BS. checking whether the first BS and the second BS are same or not, wherein, when the first BS and the second BS are same and when the RRC connection reconfiguration message is considered as invalid, the UE initiates RRC connection reconfiguration procedure and informs the first BS of failure for the configuring the second cell, wherein, when the first BS and the second BS are same and when the RRC connection reconfiguration message is considered as valid, the UE autonomously disables the TTI bundling for the first BS, informs the first BS of disabling the TTI bundling, and configures the second cell for the first BS, and wherein, when the first BS and the second BS are different, the UE keeps using the TTI bundling for the first BS and configures the second cell for the second BS.