Method and device for selecting synchronization reference in NR V2X

A first device configured to perform wireless communication, the first device comprising:

• one or more memories storing instructions;
• one or more transceivers;
• and
• one or more processors connected to the one or more memories and the one or more transceivers, wherein the one or more processors execute the instructions to:
• obtain information related to a sidelink (SL) bandwidth part (BWP);
• obtain SL synchronization priority order information which is set to Global Navigation Satellite Systems (GNSS)-based synchronization;
• obtain information representing whether or not base station (BS)-related synchronization references are disabled to be selected;
• detect a synchronization signal transmitted through the SL BWP by GNSS-related synchronization references or other user equipments (UEs), based on the information representing that the BS-related synchronization references are disabled to be selected;
• and
• perform synchronization with one synchronization reference, based on the synchronization signal, among the GNSS-related synchronization references or the other UEs,
• wherein, based on the SL synchronization priority order information set to the GNSS-based synchronization, synchronization references include the GNSS-related synchronization references, the BS-related synchronization references, and the other UEs,
• wherein the GNSS-related synchronization references include a UE directly synchronized with a GNSS, and a UE indirectly synchronized with the GNSS, and
• wherein the BS-related synchronization references include a BS, a UE directly synchronized with the BS, and a UE indirectly synchronized with the BS.

A processing device configured to control a first device performing wireless communication, the processing device comprising:

• one or more processors;
• and
• one or more memories operably connected to the one or more processors and storing instructions, wherein the one or more processors execute the instructions to:
• obtain information related to a sidelink (SL) bandwidth part (BWP);
• obtain SL synchronization priority order information which is set to Global Navigation Satellite Systems (GNSS)-based synchronization;
• obtain information representing whether or not base station (BS)-related synchronization references are disabled to be selected;
• detect a synchronization signal transmitted through the SL BWP by GNSS-related synchronization references or other user equipments (UEs), based on the information representing that the BS-related synchronization references are disabled to be selected;
• and
• perform synchronization with one synchronization reference, based on the synchronization signal, among the GNSS-related synchronization references or the other UEs,
• wherein, based on the SL synchronization priority order information set to the GNSS-based synchronization, synchronization references include the GNSS-related synchronization references, the BS-related synchronization references, and the other UEs,
• wherein the GNSS-related synchronization references include a UE directly synchronized with a GNSS, and a UE indirectly synchronized with the GNSS, and
• wherein the BS-related synchronization references include a BS, a UE directly synchronized with the BS, and a UE indirectly synchronized with the BS.