Patent ID: 8493841

Claim:
A wireless communication system, comprising: a first node; a plurality of second nodes; and a plurality of third nodes, wherein the third nodes communicate with the first node through the second nodes, each second node transmits control information to neighboring third nodes, each third node transmits control information to neighboring second and third nodes, each third node calculates link costs of single-hop wireless links with its neighboring nodes from a reception status of the control information, the control information transmitted by each second node includes a path cost indicating a cost of a path between the first node and the second node, the control information transmitted by each third node includes a path cost indicating a cost of a path between the first node and the third node, calculated by adding the link cost of a link by which the third node receives control information from one of the second or third nodes to the path cost included in the received control information, each third node uses the received control information to select one of the second nodes through which to communicate with the first node and select one of the second or third nodes as a parent node serving as a destination of a first hop when the third node communicates with the first node, when one of the second nodes has failed, the first node detects the failed second node and notifies the third nodes of the failed second node, after selecting parent nodes, the third nodes transmit routing information to the first node, when one of the third nodes selects a different second node in response to notification of a failed second node, if said one of the third nodes is selected as a parent node by another one of the third nodes, said one of the third nodes delays transmission of the routing information for a prescribed time, but if said one of the third nodes is not selected as a parent node by any other one of the third nodes, said one of the third nodes transmits the routing information immediately, and the prescribed time increases with increasing distance from the failed second node.