With rapid increasing of ships, the channel load of AIS system in dense navigable water areas also increses rapidly.Time slot conflict in systems, channel congestion, and anomaly communication of AIS network, which cause reduction of reliability for its application, is becoming a hidden hazard of ship navigation safety.In order to accurately and timely reflect the actual situation of communication performance in AIS network, indicators are monitored in real-time based on AIS integrated application platforms.Based on the AIS data of Wuhan section of Yangtze River, the communication performance of AIS network in this water area is evaluated using one week data from five aspects, which are network capacity, network channel load, network throughput, network utilization, and network blocking rate.The tendency and limit state of the communication performance in AIS network is studied by a simulation.The results show that the channel load rate of AIS network in Wuhan section is about 15%, while its throughput is close to 100%, and communication performance is good.If the number of ships increases when the channel load rate reaches 60.5%, communication congestion will be achieved in the AIS network, and the number of ships in 13 motion states are obtained when communication congestion occurs.The results objectively and accurately reflect the communication performance of AIS network in studied area, and can provide technical supports to monitor, manage, and control the AIS system for inland maritime authorities.%随着船舶数量的日益增长,密集通航水域AIS系统的信道负载迅速增大,出现系统时隙冲突、信道拥塞、AIS网络通信异常等现象,导致AIS应用的可信度降低,成为船舶航行安全的隐患.为了更为精确、及时地反映AIS网络通信性能的实际状况,基于AIS综合应用平台实时监测AIS网络通信性能指标,以长江武汉段AIS数据为基础,选取一周的指标监测数据,从网络容量、网络信道负载率、网络吞吐率、网络阻塞率、网络利用率5个方面对该水域AIS网络通信性能进行评价分析,并通过仿真研究了AIS网络通信性能的变化趋势和极限状况.研究结果表明现阶段长江干线武汉段AIS网络信道负载率在15%左右,吞吐率接近100%,通信性能良好.随着船舶数的增加,网络信道负载率达到60.5%时,出现AIS网络通信阻塞现象,并得到通信阻塞时13种运动状态下的船舶数分布.研究结果客观、准确地反映了研究水域的AIS网络通信性能,为内河海事主管机关监控、管理、调控AIS系统提供技术支撑.
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