【作者】 崔建平；

【导师】 吴青；

【作者基本信息】 武汉理工大学 ， 机械电子工程， 2010， 硕士

【摘要】 内河是指处于一个国家之中的河流。我国河流众多,以长江、珠江、黑龙江三大水系和京杭大运河为主干线组成了我国“三横一纵”为主体的内河网。内河的典型特点是河道狭窄、弯曲、河流湍急。在内河航行中,传统的导航仪器如雷达、GPS等由于各自的局限性很难达到安全导航、避让的作用,而且它们也无法获得目标船的静态信息(如船名、呼号、吃水、目的地、到达时间等)和动态信息(如船位、船速、船首向、航迹向、转向率等),所以仅仅依靠这些工具很难达到现代安全通航的要求。船载自动识别系统(AIS)的诞生弥补了以往导航仪器的不足,为内河安全航行开辟了一条崭新的道路。AIS在我国内河航行中的应用已经越来越广泛。作为一种船舶监测系统,并隶属于无线移动通信网络范畴,AIS在内河中通信的可靠性直接决定了其应用前景,因此探讨内河中AIS的通信可靠性对保障船载航行安全具有重要的意义。影响AIS通信可靠性的因素众多,在特定的内河环境中,由于其特殊的地理环境,其影响因素又会与海上不同。本文研究的重点是内河AIS基站和AIS船台之间的通信。AIS基站的工作原理和AIS船台的工作原理大同小异。无线通信系统的可靠性主要受移动无线信道的制约,研究和仿真无线通信系统首先要认识信道本身的特性并通过传播预测模型研究电波的传播规律。在充分考虑适用性、可靠性等因素之后,选择了奥村模型和国家标准模型这两种传播预测模型。Okumura模型是奥村等人根据在日本近郊测试的大量数据,统计出用曲线表示的传播损耗图。该模型的特点是完全基于实测数据,以曲线图表的形式给出,在计算机上应用不方便。为此,Hata等人在此基础上做了分析总结出了一套经验公式,即Okumura-Hata(奥村—哈塔)模型。Okumura-Hata模型是移动通信中应用较为广泛的预测模型,是根据测试数据统计分析得到的经验公式,其适用频率范围为150-1500MHz,适用距离为1～35km,基站有效天线高度在30-200m之间,移动台有效天线高度在1～10m之间。奥村—哈塔模型是以市区传播损耗模型为标准,其它地形的传播损耗模型在它的基础上做了修正。GB/T14617.1-93模型也是应用较为广泛的一种模型。我国对奥村—哈塔模型进行了修正后,在1994年纳入了国家标准,即国家标准模型。它扩展了传播路径,引入了建筑物密度修正因子等,是一个理论与经验相结合的模型,更加适用于中国地形地貌特点。本文利用这两种模型对AIS通信系统的可靠性进行了研究,开发了仿真系统,并进行了仿真分析。在实验的基础上,验证了奥村模型在武汉地区应用的适用性,并进行了修正,得到了本地化的预测模型。更多还原

【Abstract】 Inland River means the river flows through one country. Our country is watered by numerous rivers. And the main framework of the inland river network can be seen as a structure called "Four longitudinal and four horizontal", which is composed of Changjiang River, Pearl River, Heilongjiang River and Beijing-Hangzhou Grand Canal. Narrow and curved channels and torrents are the characters of the inland waterway. Due to the limitation of traditional navigator such as radar and GPS, these equipments cannot ensure safety in sailing and avoidance, and they also cannot capture the static information(such as name,depth,destination,arrival time and etc.)and dynamic information(such as position,speed,heading,rotation rate and etc.). So only use these equipments cannot meet the requirements of safety in navigation. Now, Automatic Identification System (AIS) overcome the shortage of traditional navigators, which opens up a new way for safety navigation of inland rivers. AIS is more and more widely applied in the inland navigation of our country. As a kind of Ship Monitoring System, which belongs to wireless mobile communication network, the reliability of communication determines the application of AIS. So the research of reliability of communication of AIS in inland navigation is important for the safety of navigation.The elements which affect the reliability of communication are multiple, and because of special geographical environments, these elements of inland navigation are different from Maritime.The key point of this research is on the communication between the base station and ship berth of AIS. The work principle of base station of AIS is similar to ship berth of AIS. The reliability of wireless communication system is mainly affected by wireless channel. To study and simulate wireless communication system must analyze the characters of channel and use forecast model to study the broadcast discipline of radio firstly. Based on the consideration of factors of application and reliability and so on, this thesis chooses Okumura-Hata model and national standard model.According to the large amount of data tested in japan,Okumura and others have made the curve chart of propagation loss.The feature of the model is that the result of model given by the form of curves is completely based on measured data,it’s inconvenient to apply in computer. So, Hata and some other people have analyzed on this basis and summarized a set of empirical formula,that is Okumura-Hata model. Okumura-Hata model is a kind of prediction model widely used in the mobile communication, it is an empirical formula obtained by the statistical analysis of test data, its applicable frequency range is 150～1500MHz, the distance is 1～20km,the effective antenna height of base station is 30～200m,and the mobile station’s is 1～10m.Okumura-Hata model is established as the standard by urban propagation loss,the other terrains has made some amendments on this basis.GB/T14617.1-93 model is also a widely used model.In 1994, Okumura-Hata model was brought in the national standard after our country made some modifications, that is the national standard model.It extends the transmission path, leads into the density correction factor of the building and so on, it’s a combination of theoretical and empirical models, so it’s more suitable for the features of Chinese terrain.In this thesis, these two models are used to study the reliability of AIS communication system, and make some simulation analysis.On the basis of experiment, verifying the accuracy of Okumura-Hata models’application in wuhan, and doing some modifications.更多还原