Method and apparatus for performing handover procedure in wireless communication system

Abstract

A method performed by a terminal in a wireless communication system includes: receiving, from a base station, a radio resource control (RRC) reconfiguration message including configuration information for conditional handover; identifying a cell for conditional handover based on the configuration information for conditional handover; and triggering a packet data convergence protocol (PDCP) status report for a radio bearer, according to an execution of a conditional handover for the identified cell for conditional handover.

What is claimed is: 
     
         1 . A method performed by a terminal in a wireless communication system, the method comprising:
 receiving, from a base station, a radio resource control (RRC) reconfiguration message comprising configuration information for conditional handover;   identifying a cell for conditional handover based on the configuration information for conditional handover; and   triggering a packet data convergence protocol (PDCP) status report for a radio bearer according to an execution of a conditional handover for the identified cell for conditional handover.   
     
     
         2 . The method of  claim 1 , further comprising reestablishing a PDCP entity corresponding to the RRC reconfiguration message,
 wherein the PDCP status report is triggered in response to the reestablishment of the PDCP entity.   
     
     
         3 . The method of  claim 1 ,
 wherein the RRC reconfiguration message comprises PDCP configuration information, and   wherein the PDCP status report is triggered in case that the PDCP configuration information comprises information indicating that the PDCP status report is required.   
     
     
         4 . The method of  claim 1 , wherein the radio bearer is an acknowledged mode (AM) data radio bearer (DRB). 
     
     
         5 . The method of  claim 1 , wherein the configuration information for conditional handover comprises information of at least one candidate cell for conditional handover and information of conditions for conditional handover. 
     
     
         6 . The method of  claim 5 , wherein the identifying of the cell for conditional handover comprises identifying the cell for conditional handover from among the at least one candidate cell based on the information of conditions for conditional handover. 
     
     
         7 . The method of  claim 1 , further comprising transmitting the PDCP status report to the identified cell for conditional handover. 
     
     
         8 . A terminal in a wireless communication system, the terminal comprising:
 a transceiver; and   at least one controller configured to:
 receive, from a base station, a radio resource control (RRC) reconfiguration message comprising configuration information for conditional handover, 
 identify a cell for conditional handover based on the configuration information for conditional handover, and 
 trigger a packet data convergence protocol (PDCP) status report for a radio bearer according to an execution of a conditional handover for the identified cell for conditional handover. 
   
     
     
         9 . The terminal of  claim 8 ,
 wherein the at least one controller is further configured to reestablish a PDCP entity corresponding to the RRC reconfiguration message, and   wherein the PDCP status report is triggered in response to the reestablishment of the PDCP entity.   
     
     
         10 . The terminal of  claim 8 ,
 wherein the RRC reconfiguration message comprises PDCP configuration information, and   wherein the PDCP status report is triggered in case that the PDCP configuration information comprises information indicating that the PDCP status report is required.   
     
     
         11 . The terminal of  claim 8 , wherein the radio bearer is an acknowledged mode (AM) data radio bearer (DRB). 
     
     
         12 . The terminal of  claim 8 , wherein the configuration information for conditional handover comprises information of at least one candidate cell for conditional handover and information of conditions for conditional handover. 
     
     
         13 . The terminal of  claim 12 , wherein at least one controller is further configured to identify the cell for conditional handover from among the at least one candidate cell based on the information of conditions for conditional handover. 
     
     
         14 . The terminal of  claim 8 , wherein at least one controller is further configured to transmit the PDCP status report to the identified cell for conditional handover.