Reference information for reference signal time difference

An apparatus in a radio access network, the apparatus comprising at least one processor, and at least one memory storing instructions which, when executed by the at least one processor, cause the apparatus at least to:

• select at least one user device from a plurality of candidate user devices provided by the network as a reference for reference signal time difference (RSTD) measurements;
• measure a plurality of RSTDs between at least two respective positioning reference signals and a sidelink positioning reference signal received from the at least one user device selected as the reference, wherein the plurality of RSTDs are measured relative to the same sidelink positioning reference signal received from the at least one user device selected as the reference;
• and
• transmit, to a network element of a core network, a report comprising:
• an identifier of the at least one user device selected as the reference for the RSTD measurements,
• an identifier of a resource associated with the sidelink positioning reference signal received from the at least one user device,
• synchronization source information indicating at least one synchronization source of the at least one user device,
• a time stamp of the sidelink positioning reference signal received from the at least one user device, and
• a measurement report indicative of the plurality of measured RSTDs relative to the at least one user device selected as the reference for the RSTD measurements.