Method and device for transmitting or receiving preamble for random access during handover in wireless communication system

A UE performing random access during handover from a source cell to a target cell in a wireless communication system, comprising:

• a transceiver;
• and
• at least one processor configured to transmit, through the transceiver, measurement information about the source cell and the target cell to a first base station of the source cell;
• receive, through the transceiver, a radio resource control (RRC) message including random access channel (RACH) configuration information about the target cell from the first base station;
• and
• sequentially transmit, through the transceiver, at least one preamble for the random access to a second base station of the target cell based on the RACH configuration information,
• wherein the RACH configuration information includes a plurality of synchronization signal block (SSB) indices and a plurality of preamble indices mapped to a plurality of RACH occasions (ROs) for the UE to transmit the at least one preamble in a random access procedure as list information.

A method performed by a base station of a target cell for random access during handover from a source cell to the target cell in a wireless communication system, the method comprising:

• transmitting a radio resource control (RRC) message including random access channel (RACH) configuration information about the target cell to a first base station of the source cell;
• and
• sequentially receiving at least one preamble for the random access from a UE based on the RACH configuration information,
• wherein the RACH configuration information includes a plurality of synchronization signal block (SSB) indices and a plurality of preamble indices mapped to a plurality of RACH occasions (ROs) for the UE to transmit the at least one preamble in a random access procedure as list information.

A base station of a target cell supporting random access during handover from a source cell to the target cell in a wireless communication system, comprising:

• a transceiver;
• and
• at least one processor configured to transmit, through the transceiver, a radio resource control (RRC) message including random access channel (RACH) configuration information about the target cell to a first base station of the source cell;
• and
• sequentially receive, through the transceiver, at least one preamble for the random access from a UE based on the RACH configuration information,
• wherein the RACH configuration information includes a plurality of synchronization signal block (SSB) indices and a plurality of preamble indices mapped to a plurality of RACH occasions (ROs) for the UE to transmit the at least one preamble in a random access procedure as list information.