Abstract
Warning information distribution (WID) is a key aspect in effective disaster risk reduction. All countries in the world are engaged in establishment and improvement of WID system over all kinds of transmission media. China has established an effective meteorological WID system based on radio, television, telephone, Internet, short message service, LED screen, village horn, etc. The system will be upgraded into a national level public emergencies WID system for all hazard events. But due to signal coverage, some areas of China are still uncovered and the time effect of WID still needs improving.Beidou satellite (BDS) is a navigation satellite system of China with short message communication capability. Its communication signal can cover all Chinese territory and surrounding areas. BDS has two communication methods, peer to peer and broadcast. The broadcast manner is of great value in improving the coverage and time effect of WID in China, especially in marine and distant land areas.However, WID based on BDS has some key problems such as low transmission rate, huge amount of redundant information (having no relevance to local area) and low reliability of long message distribution. To solve these problems, improved schemes are proposed on the system architecture, protocol stack and key issues of WID based on BDS. Feasible solutions including parallel transmission of uplink terminal, warning information encoding, affected area perception and unified message compensation are given. Based on those methods, a prototype system is established based on the protocol design including warning information network distribution, warning information BDS distribution and warning information BDS transmission.The prototype system is composed of integrated distribution platform, BDS distribution gateway, BDS command and control terminal, BDS, and BDS warning terminal. Integrated distribution platform is used for warning information input, revision, verification and distribution. BDS distribution gateway is used for protocol conversion from network distribution to BDS distribution. BDS warning terminal is used to receive warning information from BDS, filter out redundant information and give out severity discriminated warnings. Redundant information filtering is based on affected area encoding of warning message in three manners which are geocode, circle and polygon. Results can provide comprehensive analytical methods and practical experience to the establishment of WID system based on BDS or other satellite systems.
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