Method and apparatus for handover in a mobile communication system
The present invention relates to a handover method for a mobile communication system. The handover method according to the present invention informs a current state to a serving base station(BS) when a re-entry process has been delayed or a handover has failed due to an error occurred in the handover procedure during handover, and receives from the serving BS a status information response message containing available interval and unavailable interval reset information and link disconnection time reset information for extending the link disconnection time. So, the present invention minimizes or prevents a handover delay or extend a link disconnection time with the serving BS, thereby allowing a terminal to receive a continuous service even during the handover procedure.
1. A method for a User Equipment (UE) to perform handover in a mobile communication system, the method comprising:
receiving a handover command message from a serving base station (BS), the handover command message containing information related to a target BS, information related to an available interval enabling data transmission to and data reception from the serving BS during handover, information related to an unavailable interval not enabling data transmission or reception during handover and information related to time of disconnection of a link with the serving BS;
performing a network entry process with the target BS;
transmitting status information to the serving BS when an error has occurred in the network entry process;
receiving a status information response message from the serving BS, the response message containing available interval and unavailable interval reset information and reset link disconnection time information for extending the link disconnection time;
enabling the serving BS to provide a data transmitting and receiving service during the available interval; and
re-performing the network entry process with the target BS and disconnecting the link at the reset link disconnection time,
wherein the status information contains at least information related to a type of the network entry process, information related to a cause and an occurrence time of the error, or action request information requested from the serving BS.
2. The method of claim 1 , wherein the handover command message further contains information related to a level expected to be provided by the target base station BS and information related to an action time for initiating the network entry process.
3. The method of claim 1 , wherein the status information is transmitted by being included in a Medium Access Control (MAC) management message, a piggyback or a Channel Quality Indicator Channel (CQICH).
4. The method of claim 1 , wherein the network entry process is a Code Division Multiple Access (CDMA) code ranging or a ranging process through a Medium Access Control (MAC) message.
5. The method of claim 4 , further comprising receiving error information from the target BS via a ranging response message when the CDMA code ranging or the MAC message ranging has failed.