Effective method of handover in wideband radio access system

A method supporting handover in a wireless communication system, the method comprising:

• transmitting, by a serving base station to a mobile station, a handover command message including:
• information related to a disconnect time,
• wherein the information related to the disconnect time is configured in units of frames,
• wherein the disconnect time is a time for the mobile station to disconnect from the serving base station, and
• wherein the disconnect time indicates a time point at which the serving base station stops sending downlink data to the mobile station and stops an uplink resource allocation, and
• an action time for the mobile station to transmit a ranging request to a target base station;
• and
• if a connection with the mobile station cannot be maintained until the disconnect time,
• receiving, by the serving base station from the mobile station, a handover indication message for disconnecting from the mobile station from the serving base station earlier than the disconnect time;
• and
• buffering, by the serving base station, downlink data for the mobile station without transmitting the downlink data to the mobile station before the disconnect time.

A mobile station, comprising:

• a Radio Frequency (RF) circuit configured to transmit and receive radio signals to and from the outside;
• and
• a processor operatively connected to the RF circuit and configured to:
• receive a handover command message from a serving base station, the handover command message including:
• information related to a disconnect time,
• wherein the information related to the disconnect time is configured in units of frames,
• wherein the disconnect time is a time for the mobile station to disconnect from the serving base station, and
• wherein the disconnect time indicates a time point at which the serving base station stops sending downlink data to the mobile station and stops an uplink resource allocation for the mobile station, and
• an action time for the mobile station to transmit a ranging request to a target base station,
• if the mobile station cannot maintain a connection with the serving base station until the disconnect time, transmit to the serving base station a handover indication message for disconnecting the mobile station from the serving base station earlier than the disconnect time, and
• transmit the ranging request to the target base station based on a dedicated ranging code at the action time.