Apparatus and method for providing handover support information in mobile communication system

A mobile station in a mobile communication system, the mobile station comprising:

• a transceiver;
• and
• at least one processor,
• wherein the at least one processor is configured to:
• control the transceiver to receive, from a serving cell, a message including first information indicating a time to trigger (TTT) for at least one first neighbor cell and an alternative TTT for at least one second neighbor cell, and second information indicating at least one list of the at least one second neighbor cell, wherein the TTT and the alternative TTT are included in separate fields of the message,
• identify the TTT and the alternative TTT included in the message, and
• control the transceiver to transmit, to the serving cell, a measurement report for the at least one second neighbor cell based on the alternative TTT instead of the first TTT,
• wherein the alternative TTT is used for the at least one second neighbor cell instead of the TTT, and
• wherein the second information further includes a physical cell identifier range indicating a range of physical cell identities in the at least one list.