Method of handling an inter rat handover in wireless communication system and related communication device

Abstract

A method of handling an inter-RAT handover for a mobile device in a wireless communication system includes when, via a handover from a serving network using a first RAT to a target network using a second RAT, the mobile device succeeds in establishing a connection to the target network and has packet switched data for transmission, transmitting a predetermined radio resource control message, indicating existence of a packet switched signaling connection of the mobile device, to the target network.

1 . A method of handling an inter-radio access technology, hereinafter called RAT, handover for a mobile device in a wireless communication system, the method comprising:
 when, via a handover from a serving network using a first RAT to a target network using a second RAT, the mobile device succeeds in establishing a connection to the target network and has packet switched data for transmission, transmitting a predetermined radio resource control message, indicating existence of a packet switched signaling connection of the mobile device, to the target network.   
     
     
         2 . The method of  claim 1 , wherein performing the handover from the serving network of the first RAT to the target network of the second RAT comprises receiving a HANDOVER TO UTRAN COMMAND message excluding a “RAB info” (“Radio Bearer info”) information element. 
     
     
         3 . The method of  claim 1 , wherein the predetermined RRC message is a UPLINK DIRECT TRANSFER message.