Synchronization for Sidelink Based on Prioritization of Synchronization Signals

A computer-readable storage medium that stores instructions for execution by processing circuitry of a User Equipment (UE), the operations to configure the processing circuitry to:

• attempt to detect synchronization signals, including Long Term Evolution (LTE) synchronization signals from Evolved Node-Bs (eNBs), New Radio (NR) synchronization signals from Next Generation Node-Bs (gNBs), and sidelink synchronization signals (SLSSs) from other EIEs;
• if the UE detects two or more synchronization signals, select one of the detected synchronization signals based on a set of prioritization rules, comprising:
• using a first prioritization rule based on types of the detected synchronization signals, wherein:
• LTE synchronization signals and NR synchronization signals are of equal priority, and are of higher priority than SLSSs;
• using a second prioritization rule based on synchronization hop information, wherein:
• SLSSs from EIEs directly synchronized to an eNB or gNB are of higher priority than SLSSs from UEs that are indirectly synchronized to an eNB or gNB,
• using a tie-breaking rule based on corresponding signal quality measurements;
• and
• determine a reference timing for sidelink transmissions by the LIE based on the selected synchronization signal.

An apparatus comprising:

• at least one processor, configured to cause a user equipment (UE) to:
• attempt to detect synchronization signals, including Long Term Evolution (LTE) synchronization signals from Evolved Node-Bs (eNBs), New Radio (NR) synchronization signals from Next Generation Node-Bs (gNBs), and sidelink synchronization signals (SLSSs) from other UEs;
• if the UE detects one synchronization signal, determine a reference timing for sidelink transmissions by the UE based on the detected synchronization signal;
• if the UE detects two or more synchronization signals, select one of the detected synchronization signals based on a set of prioritization rules, wherein:
• LTE synchronization signals and NR synchronization signals are of higher priority than SLSSs;
• an SLSS from a UE that is directly synchronized to an eNB or a gNB is of higher priority than an SLSS from a UE that is indirectly synchronized to an eNB or a gNB;
• of a plurality of synchronization signals that includes one or more LTE synchronization signals and/or one or more NR synchronization signals, the synchronization signals are prioritized based on reference signal receive power (RSRP).