Device-to-device synchronization in wireless communications

A method for wireless communication at a second user equipment (UE), comprising:

• identifying a set of resources to monitor for sidelink synchronization signals for synchronizing a sidelink communications link between a first UE and the second UE, the sidelink synchronization signals including one or more of a first sidelink synchronization signal that provides coarse synchronization or a second sidelink synchronization signal that provides fine synchronization and an identifier of the first UE;
• receiving the first sidelink synchronization signal from the first UE on the set of resources;
• determining, based at least in part on the first sidelink synchronization signal, a coarse timing for the second sidelink synchronization signal;
• receiving, based at least in part on the coarse timing, the second sidelink synchronization signal;
• determining, based at least in part on the second sidelink synchronization signal, a fine timing for synchronizing communications with the first UE and the identifier of the first UE;
• and
• transmitting, to the first UE, a sidelink connection request based at least in part on the fine timing and the identifier of the first UE.

A method for wireless communication at a base station, comprising:

• identifying at least a first user equipment (UE) that is to provide a sidelink communications link with one or more other UEs;
• determining, based at least in part on one or more channel parameters associated with the first UE, a set of sidelink synchronization signals for synchronizing the sidelink communications link between the first UE and the one or more other UEs, wherein the set of sidelink synchronization signals include first sidelink synchronization signal that provides coarse synchronization and a second sidelink synchronization signal that provides fine synchronization and an identifier of the first UE;
• and
• transmitting configuration information to at least the first UE that indicates the set of sidelink synchronization signals.

An apparatus for wireless communication at a first user equipment (UE), comprising:

• a processor,
• memory coupled with the processor;
• and
• instructions stored in the memory and executable by the processor to cause the apparatus to:
• identify a set of sidelink synchronization signals for transmission to at least a second UE for synchronizing a sidelink communications link between the first UE and at least the second UE, the set of sidelink synchronization signals including one or more of a first sidelink synchronization signal that provides coarse synchronization or a second sidelink synchronization signal that provides fine synchronization and an identifier of the first UE;
• transmit the set of sidelink synchronization signals based at least in part on the identifying;
• receive, from the second UE, a sidelink connection request based at least in part on the transmitted set of sidelink synchronization signals;
• and
• establish the sidelink communications link with the second UE responsive to the sidelink connection request.