A Study On CWDSS Data Communication System Based On STDMA

According to our country's more and more austere waterborne traffic condition, for reducing waterborne traffic accidents, Prof. Fuwen Pang brings forward Chinese Waterborne Distress and Safety System which is compatible with GMDSS and will be implemented in Chinese A1 sea area, fresh water and lakes.As a subsystem of CWDSS, CWDSS Data Communication System's main function is broadcast vessel's automatic identification message, routine message and distress and safety message to other vessels and broadcasting stations on shore, thereby can realize the communication with other vessels and broadcasting stations on shore. According to our country's condition, I try composing CWDSS Data Communication System based on STDMA technology. This system integrates vessel's automatic identification message, routine message ,distress and safety message and so on, making the best of our country's present resources, thereby can reduce or avoid waterborne accidents from happening to the maximum.CWDSS Data Communication System adopts STDMA wireless communication protocols according with OSI reference model of ISO. It divides channel into fixed distant time intervals. 2 250 time intervals compose a frame. A frame lasts 1 minute and synchronizes with UTC. All time intervals can be used by broadcasting stations in the wireless data chain. CWDSS Data Communication System realizes self organized communication by including next broadcasting time in every transmitted message, informing other vessels not to engross this time interval, thereby obligate next broadcasting time. Besides, CWDSS Data Communication System selects time interval again in some time range from 3 to 8 minutes to avoid possible communication collision because of broadcasting stations' moving. At the same time, CWDSS Data Communication System deals with possible communication collision because of communication chain capacity overloading by voluntary time interval reusing.CWDSS Data Communication System has broad application foreground inwaterborne shipping field in the future. It will bring revolutionary advancements to vessels control, vessels avoiding collision, waterborne search and salvation, port and narrow watercourse navigation, waterborne traffic control, ocean environment protecting and other fields.