Embodiments of a User Equipment (UE), Next Generation Node-B (gNB), Evolved Node-B (eNB) and methods of communication are generally described herein. The UE may detect one or more LTE synchronization signals from an eNB over an LTE Uu interface between the UE and the eNB. The LTE synchronization signals may be detected in resources allocated for LTE communication. The LTE synchronization signals may be detected in accordance with an LTE protocol. The UE may determine, based on the LTE synchronization signals, a reference timing and a reference frequency for NR vehicle-to-everything (V2X) communication over an NR PC5 interface with another UE.