The Stimulation Study On Network Performance Of AIS Based On LAN

Network performance evaluation is an important basis and supporting technology of network in r esearch and ap plication. As a kind of c ommunication net work system on surveillance of ship, network performance is a key problem of AIS in research an application.This paper investigates development tendency of AIS and actuality of study on network performance home and abroad and development on computer stimulation technology , then expatiates on communication principle of AIS and emphasizes analyzing STDMA protocol and network model, brings forward network performance evaluation measure on quality of service and analyzes their relations. On the basis of those, this paper establishes communication network model based on STDMA according to ITU Recommendation On the Technical Characteristics for AIS, then brings forward a way on Local Area Network to study network performance of AIS by comparing the advantages and shortcomings between several network performance evaluation methods. Finally it designs and realizes stimulator on network performance of AIS on LAN under Microsoft Visual C++6.0 .By the analysis of theory and stimulation with stimulator, this paper summarizes two conclusions as followed:(1)The STDMA protocol of AIS is robust enough. Channel load is usually less than 20% in most cases, that mean that report rate will exceed 500 times per minute. The successful transmission rate is closely 100%. Therefore, communication reliability and efficiency of automatic exchange of voyage message by AIS is good.(2)ln terms of the busiest VTS waters at present, the network performance of AIS can also need the actual requirements. But taking more than position reports into account, there are messages to be transmitted related to others service. It will increase channel load and decrease channel throughout performance and impact the receive and management of message from AIS station in VTS. It is necessary to take some corresponding measures in the area.Finally this paper brings forward some advices to continue to develop and enhance simulator according its problems in application.