Method and device for improving handover performance in mobile communication system
An operating method performed by a user equipment (UE) in a wireless communication system according to some embodiments of the present disclosure may include: generating a source link for transmitting and receiving data to and from a source base station; receiving, from the source base station, a radio resource control (RRC) message including configuration information for handover to a target base station; starting a timer, in response to the reception of the RRC message; transmitting, to the target base station, a message for handover to the target base station while the timer is running; and determining, in a case where the handover to the target base station fails up until the timer expires, whether to trigger RRC re-establishment, based on a state of the source link.
1 . A method performed by a terminal in a wireless communication system, the method comprising:
transmitting, to a source base station, information associated with a support of a first type handover, where the terminal maintains a connection with the source base station after receiving a radio resource control (RRC) reconfiguration message for the first type handover from the source base station until a time point after a random access to a target base station succeeds;
receiving, from the source base station, the RRC reconfiguration message including information for the first type handover associated with the target base station;
in response to receiving the RRC reconfiguration message, starting a timer;
in response to receiving the RRC reconfiguration message, performing the random access with the target base station, wherein the performing of the random access includes transmitting a preamble to the target base station;
in case that the timer expires and a radio link failure (RLF) is not detected in the source base station, transmitting, to the source base station, information indicating a failure of the first type handover associated with the target base station; and
in case that the timer expires and the RLF is detected in the source base station, performing an RRC connection re-establishment procedure.
2 . The method of claim 1 , wherein the timer includes a timer T 304 .
3 . The method of claim 1 ,
wherein the RLF is detected in the source base station, when a timer T 310 associated with the source base station expires or when a maximum number of radio link control (RLC) re-transmission associated with the source base station is reached,
wherein the timer T 310 starts when an out-of-sync indicator is transmitted from a physical layer of the terminal to an upper layer of the terminal by a preset number.
4 . The method of claim 1 ,
wherein the RRC connection re-establishment procedure is for a cell selection.
5 . The method of claim 1 ,
wherein in case that the terminal does not transmit an RRC reconfiguration complete message to the target base station until the timer expires, the first type handover associated with the target base station fails.
6 . A terminal in a wireless communication system, the terminal comprising:
a transceiver; and
at least one processor configured to:
transmit via the transceiver, to a source base station, information associated with a support of a first type handover, wherein the terminal maintains a connection with the source base station after receiving a radio resource control (RRC) reconfiguration message for the first type handover from the source base station until a time point after a random access to a target base station succeeds,
receive via the transceiver, from the source base station, the RRC reconfiguration message including information for the first type handover associated with the target base station,
in response to receiving the RRC reconfiguration message, start a timer,
in response to receiving the RRC reconfiguration message, perform the random access with the target base station, wherein performing of the random access includes transmitting via the transceiver, a preamble to the target base station,
in case that the timer expires and a radio link failure (RLF) is not detected in the source base station, transmit via the transceiver, to the source base station, information indicating a failure of the first type handover associated with the target base station, and
in case that the timer expires and the RLF is detected in the source base station, perform an RRC connection re-establishment procedure.
7 . The terminal of claim 6 , wherein the timer includes a timer T 304 .
8 . The terminal of claim 6 ,
wherein the RLF is detected in the source base station, when a timer T 310 associated with the source base station expires or when a maximum number of radio link control (RLC) re-transmission associated with the source base station is reached,
wherein the timer T 310 starts when an out-of-sync indicator is transmitted from a physical layer of the terminal to an upper layer of the terminal by a preset number.
9 . The terminal of claim 6 , wherein the RRC connection re-establishment procedure is for a cell selection.
10 . The terminal of claim 6 ,
wherein in case that the terminal does not transmit an RRC reconfiguration complete message to the target base station until the timer expires, the first type handover associated with the target base station fails.