Study Of The Shipborne Automatic Identification System And The Application Of Its Key Techniques In VTS

AIS can work by either of the two modes that are VHF/DSC and broadcasting. This paper primarily researches the broadcasting AIS, which will be better applied in the future. And the key technique of broadcasting AIS is SOTDMA (Self-Organized Time Division Multiple Access). SOTDMA technique, which was put forward in 1990s, is a new communication technique based on TDMA technique. It can automatically resolve the collision of communication in AIS.This paper first introduces the development of AIS and its configuration and function in brief, discussing the information and the calculation of the maximize range of transmission and the maximize height of the antenna, on the basis of which it analysis the theory of SOTDMA and establish the communication network model based on SOTDMA. It defines the relational parameters and analyses in theory and makes simulation to verify the theory. In this way it obtains the channel characteristic of AIS adopted SOTDMA. It continues with the analysis of the transmission format of AIS information, and finally it expects the future applications in navigational field.By the analysis of theory and the simulation with computer this paper summarizes several conclusions as followed:(1) The broadcasting AIS based on SOTDMA has such virtues as strong ability of anti-jamming, high speed of transmission, large capability and short time of information updating. It fits the requirement of the marine mobile communication environment for the communication characteristic of ship. And AIS will bring the convenience for the safety on the sea and the traffic management of VTS in the future.(2) By Discussing the information format and its contents, the synchronization of system, the transmission delay, and the protect time, it is concluded the calculation of the maximize range of transmission and the maximize height of the antenna limited by the protect time of transmission delay, which can be applied in the construction of AIS ship梥hore system.(3) By the demo of the allocation of the slots with "self-organized" in SOTDMA protocol and the result of the execution of the simulation program, the conclusion is produced as: the communication of AIS adopted SOTDMA protocol has a lower block rate and a higher success rate of sending. It has good performance of communication system if the system is not over-loading. Even over-loading, theinsystem will still meet with the lowest request of communication system. (4) According to the result of the simulation this paper brings forward several ways to manage the AIS ships in order to resolve the problem in the port of high traffic density, which plays an important role in marine traffic management and collision avoiding in the future.