Patent ID: 7697890

Claim:
A communication device of a communication system in which a wireless multi-hop network is structured with a plurality of the communication device and a collecting communication device, transmission information from each of the communication devices being sequentially relayed by communication devices that are closer to the collecting communication device for the transmission information to reach the collecting communication device, the communication device comprising: a transmission and reception processing section that is controlled to turn on and off in accordance with transmission and reception timings for transfers of ordinary transmission information during transfers of ordinary transmission of information; an urgent information transmission section that appends a flag indicating urgency to information for which collection to the collecting communication device is urgently required and transmits the information, the information being information whose transmission source is the present communication device or the information to be relayed, and the urgent information transmission section, if a state of the present communication device at the time of appending and transmission is a usual state, setting the transmission and reception processing section to be continuously on and switching the present communication device to an urgency propagation verification state for verifying a relay of the information with the urgent flag appended by one of the communication devices which is a relay destination; an urgency propagation verification section that, in the urgency propagation verification state, verifies that the urgent flag is appended to information relayed by the relay destination communication device, to which the information with the urgent flag appended has been provided from the present communication device, for verifying the relay of urgent information by the relay destination and, when verification is achieved, sets the transmission and reception processing section to be continuously on and switches the present communication device to an urgent state for promptly relaying received information; an urgent information retransmission section that retransmits the urgent information if the urgency propagation verification section has not achieved verification of the relay of the urgent information by the relay destination; and a retransmitted urgent information transfer section that, when urgent information that has been retransmitted is received, immediately transmits this urgent information.