Study On Communication Performance Of Automatic Identification System Based On TDMA

With the development of economic globalization, the navigation gets a chance to have a rapid development and the traffic on the sea is increasingly busy, which put forward higher request to marine technology. Because of its own limitations, the trsditional martime recognition technology has been difficult to adapt to the demands of modern navigation. So, the Automatic Identification System (AIS) arises at the historic moment.AIS works on the marine VHF, belonging to cellular mobile communication category. STDMA is the key technology of AIS. As a wireless communication system, the communication performance is very important to the research and application of AIS.Firstly in this paper, the development of AIS and its basic work principles are introduced birely, and also the main performance indexes related to the communication performance of AIS. Then, based on the related international standards set up by international organizations, the network performance of AIS, such as throughput and monitoring radius, were profoundly studied. The main achievement of this paper is shown as follows:1. The principle of self-organization communication of AIS is profoundly studied in this paper. And the reception performance of base station especially under the condition of multi-users conflicts in the system is profoundly analysed. Then, the simulation model is established in this paper. Through computer simulaton, the reception performance of base station and throughput in the system can be obtained under different channel load.2. This paper adopts the method of zoning discussion to analyse the throughput performance in the AIS system. That is, firstly we consider that the receiver Rx is in the center of the area, and divide the surrounding area into several annuluses with different radius. Then, the throughput preformance can be analysed in every annulus. In the actual communication AIS system, the monitoring radius of base station is far wider than that of ship station. So we define the most periphery area as Outlying Zone. Through discussion and analysis, the throughput model of different regions can be established, stimulated according to different monitoring radius of ship station. Then the corresponding conclusions can be obtained according to the simulation results.3. Based on the analysis of electromagnetic wave transmission loss model, the farthest distance under the path loss and noise loss can be obtained. Then, this paper compares among the farthest distance, visible distance and monitoring radius, and presents a new method to calculate the monitoring radius based on the traditional model. The new method inludes the characteristics of sea propagation envieonment, which greatly improves the calculation precision of the model.