Application Of Wireless Ad Hoc Net In Air-defense Alarm System

The construction of air-defense alarm is an important part of the civilair-defense works, which is related to the safety of the country and people’s lives.The majority of civil air-defense alarm networks is in the city. Compared withdeveloped countries, there are many gaps in many aspects such as real-time, waysof control，anti-interference and invulnerability.In order to increase the distance of the signal and improve the control rate forthe entire network, sometimes we manually set a number of relay nodes in thenetwork. But too much relay nodes will lead to response confusion, and coupledwith the communication frequency being limited, frequency aliasing will be veryserious which even causes false alarms. In this essay, it proposed a use of ad hocnetwork to achieve the intelligent networking of civil air-defense alarm network,with deep study of the ad hoc technology combined with its own characteristics. Allnodes of the entire network can be stably controlled with least hops. It also has theability to improve anti-interference capability of the system.All terminals with radio transceiver can be transformed into the terminal andrelay-enabled devices, so it meets the basic condition for building an ad hoc netwhich needs equal nodes. After creating a node information table based on twoimportant parameters dependence and reliability, intelligent network buildsautomatically from the initial node in each transmission of the system. It can selectcertain terminals as relay nodes intelligently to communicate in the specified band.And it gives a solution to the update of the information table and how to insert andremove fixed or temporary nodes.After described the new terminal hardware schematics, some experiments aremade based on a city’s existing civil air-defense alarm networks. The result showsthe ad hoc network technology can really enhance control rate and survivability ofthe system.