A repeater system, preferably including one or more radio transceivers, such as a 5G NR transceiver configured to communicate with other elements of a 5G NR communication network such as user equipment and/or gNBs, and a signal processor. A method for repeater operation, preferably including determining synchronization information, operating in a synchronized repeater mode, and maintaining synchronization (such as by monitoring periodic signal timing and adjusting operation timing based on the monitoring), and optionally including operating in a fallback repeater mode.