Method and apparatus for performing mobility in wireless communication system

A wireless device configured to operate in a wireless communication system comprising:

• a transceiver;
• at least one processor;
• and
• at least one memory operatively coupled to the at least one processor and storing instructions that, based on being executed by the at least one processor, perform operations comprising:
• receiving, from a network, one or more handover commands, wherein each of the one or more handover commands comprises an identifier of a corresponding handover command, and a handover condition and a random access preamble for a corresponding target cell;
• storing the one or more handover commands in a list of handover commands;
• receiving, from the network, a first handover command comprising an identifier of the first handover command;
• updating the list of handover commands based on the identifier of the first handover command;
• identifying, in the updated list of handover commands, a handover command in which a handover condition for a target cell is satisfied;
• and
• performing a random access to the target cell based on applying the identified handover command,
• wherein the updating of the list of handover commands comprises:
• determining whether a second handover command with an identifier matching the identifier of the first handover command exists among the stored one or more handover commands,
• based on a determination that the second handover command exists among the stored one or more handover commands, replacing one or more parameter values in the second handover command with one or more parameter values in the first handover command, and
• based on a determination that the second handover command does not exist among the stored one or more handover commands, adding the first handover command to the list of handover commands.

A non-transitory computer-readable medium having recorded thereon a program for performing each step of a method on a computer, the method comprising:

• receiving, from a network, one or more handover commands, wherein each of the one or more handover commands comprises an identifier of a corresponding handover command, and a handover condition and a random access preamble for a corresponding target cell;
• storing the one or more handover commands in a list of handover commands;
• receiving, from the network, a first handover command comprising an identifier of the first handover command;
• updating the list of handover commands based on the identifier of the first handover command;
• identifying, in the updated list of handover commands, a handover command in which a handover condition for a target cell is satisfied;
• and
• performing a random access to the target cell based on applying the identified handover command,
• wherein the updating of the list of handover commands comprises:
• determining whether a second handover command with an identifier matching the identifier of the first handover command exists among the stored one or more handover commands,
• based on a determination that the second handover command exists among the stored one or more handover commands, replacing one or more parameter values in the second handover command with one or more parameter values in the first handover command, and
• based on a determination that the second handover command does not exist among the stored one or more handover commands, adding the first handover command to the list of handover commands.