A method for initial timing synchronization for a WTRU to communicate with a network includes receiving an in-channel narrowband synchronization sequence from the network to enable initial coarse timing synchronization, determining coarse timing offset and a range between a beam source of a network transmitter and the WTRU, selecting a wideband sequence for fine timing synchronization using the estimated range, transmitting the selected wideband sequence for fine timing synchronization during an uplink timing occasion, receiving from the network a transmission of the selected wideband sequence for fine timing synchronization, and establishing fine timing synchronization between the WTRU and the network using the selected sequence.