Periodic Radio Resource Management (RRM) reporting from user equipments (UEs) is beneficial for a network to efficiently select a carrier with a cleaner channel to serve the UEs. To enable periodic RRM reporting from UEs, periodic beacon signal transmission for UE measurements is necessary. However, in a shared spectrum, precise periodic transmission cannot be guaranteed due to channel contention. A method of transmission with periodic time windows for beacon signal transmission is proposed to resolve potential issues. Under the proposed solution, beacon signal can be transmitted in a certain periodic fashion without frequent physical layer signaling. Furthermore, periodic beacon signal transmission for measurements can be kept with low transmission failure rate due to channel contention.