Wireless communication network system synchronization method

A synchronization method for a wireless communication network system provided with mobile radio sets that are mounted on a mobile body moving along a predetermined route, and a plurality of fixed radio sets that is spatially separated and installed along the route in such a manner that adjacent fixed radio sets perform wireless communication with each other to transmit information while relaying the information from a transmission source to a terminal fixed radio set, wherein the mobile radio sets and the fixed radio sets are time-synchronized in a communicable manner to perform communication,

• wherein at least one of the fixed radio sets is set as a base station for transmitting a synchronization packet as synchronization information, and the other fixed radio sets are set as relay stations for relaying the synchronization packet transmitted from the base station,
• wherein each of these relay stations makes a transition to a synchronization acquiring mode that is a state of waiting for reception of a synchronization packet in response to application of power, the relay station that made the transition to the synchronization acquiring mode makes a transition to a synchronization maintaining mode when receiving a synchronization packet, so that the relay station can transmit the synchronization packet during a preset own synchronization packet transmission allocation period, and the relay station in the synchronization maintaining mode makes a transition to the synchronization acquiring mode when a state without reception of any synchronization packet exceeds a preset limited time of synchronization information update.