The disclosure relates to techniques for network-based time synchronization for UE sidelink and/or uplink communication, in particular for inter-operator sidelink and/or uplink communication. The disclosure particularly relates to a base station, in particular an eNodeB or a gNodeB, for synchronizing at least one user equipment, UE, for its uplink and/or sidelink communication, the base station comprising a processor configured to: forward at least one time synchronization message of a time synchronization protocol, in particular a Precision Time Protocol, PTP or a Network Timing Protocol, NTP, between a time reference server and at least one UE receive synchronization information of the at least one UE about the synchronization between the at least one UE and the time reference server, inparticular an end-to-end delay between the time reference server and the at least one UE; and transmit a synchronization instruction to the at least one UE. The disclosure further relates to a corresponding UE and a corresponding time reference server.