Time compensation via sidelink relay in telecommunication systems

An apparatus comprising:

• a memory;
• and
• processing circuitry configured to cause the apparatus to:
• request synchronization reference source information from a user equipment,
• determine whether to conduct an offset compensation based on the synchronization reference source information, and
• in response to a determination to conduct the offset compensation,
• obtain a first propagation delay associated with the apparatus,
• determine a reference time based on the first propagation delay, and
• forward the reference time to the user equipment.

The apparatus according to 26, wherein the processing circuitry is further configured to cause the apparatus to:

• obtain the second propagation delay by transmitting a request to the user equipment to transmit a physical sidelink control channel (PSSCH) transmission with a reference signal including a transmission time and a reception time of a next PSSCH reception from the apparatus,
• transmitting a first PSSCH transmission to the user equipment,
• recording a first time of transmitting the first PSSCH transmission to the user equipment,
• receiving a second PSSCH transmission from the user equipment,
• recording a first reception time of receiving the second PSSCH transmission from the user equipment,
• receiving, from the user equipment, a Rx-Tx value corresponding to a difference between the second transmission time of transmitting the second PSSCH transmission to the apparatus and a second reception time of receiving the first PSSCH transmission from the apparatus, and
• determining the second propagation delay based on the Rx-Tx value, the first transmission time, and the first reception time.

An apparatus comprising:

• a memory;
• and
• processing circuitry configured to cause the apparatus to:
• receive, from a first user equipment, a request for time information,
• obtain a first propagation delay associated with a second user equipment,
• determine a reference time based on the first propagation delay, and
• forward the reference time to the first user equipment.

A method for synchronizing a reference time in a sidelink relay, the method comprising:

• requesting synchronization reference source information from a first user equipment;
• determining whether to conduct an offset compensation based on the synchronization reference source information;
• and
• in response to a determination to conduct the offset compensation,
• obtaining a first propagation delay of a second user equipment,
• determining a reference time based on the first propagation delay, and
• forwarding the reference time to the first user equipment.