Disclosed are devices, systems, apparatuses, methods, products, and other implementations of GNSS repeater systems and methods for improving phase and frequency alignment of RF signals transported through fiber optic communication channels. Acquired RF signals are processed at a remote outdoor unit, where they are digitized, formatted into a CPRI frame, and timestamped. The timestamped CPRI frame is then transported over a fiber optic communication channel to an indoor head end unit. The indoor head end unit extracts timestamp and digitized RF signal from the CPRI frame. The timestamp is then used to synchronize a base transceiver station (BTS) and a precision time protocol (PTP) grand master with the remote outdoor unit.