【作者】 李莹；

【导师】 陈红；

【作者基本信息】 西南交通大学 ， 通信与信息系统， 2008， 硕士

【摘要】 数据链技术是信息化军事革命的产物,拥有先进的数据链技术,就可以掌握战争的最大优势。为此,世界各国都在积极的发展该项技术,作为军队强有力的技术储备。数据链技术之所以作为未来军队的重点研究对象之一,是因为它能够通过无线的方式,将战场前方获得的各种有用数据源源不断的传回战场后方,以最快的方式为战争争取时间。数据链的两个最主要特性是实时传输和无缝覆盖,为了保证空地数据链系统的无缝覆盖,必须在移动平台移出地面固定平台的覆盖范围之前,做出恰当的越区切换,保证数据能够连续的传输。因此,本文将重点研究空地数据链系统中的越区切换策略。本文首先系统分析了空地数据链系统的组成、工作特点等,然后深入研究了移动通信系统中的越区切换设计流程,包括越区切换的控制策略,越区切换的判断准则,越区切换的算法,以及越区切换的信道分配原则。接着,针对空地数据链系统,本文设计了一套完整的越区切换方案:1)越区切换控制策略:采用地面控制中心控制;2)越区切换准则:根据地面站的通信覆盖范围来判断;3)越区切换算法:根据移动平台的飞行轨迹(固定航线和随机航线)和在网络中的角色(主控站和应答站)的不同,设计了四类不同的算法,包括越区切换时间的判断和越区切换站点的选择两个关键算法;4)越区切换的信令交互:根据空地数据链系统的工作特点,设计越区切换启动后的信令交互过程。在设计每种不同的越区切换算法之后,都做了简单的验证,保证算法的可用性。而且,按照空地数据链系统的工作方式以及硬切换和软切换的特点,定性分析了各个算法的优劣性及适用场合。最后,为了分析算法的可行性以及参数的特点,本文采用OPNET Modeler对算法做了仿真测试,分析了移动平台速度,信道误码率,轨迹信息更新间隔,以及移动平台方向变化等对算法执行中预留切换时间,切换时间,以及切换成功率等结果的影响。仿真结果与理论分析吻合,在网络允许的情况下,移动平台作为主控站时的切换为软切换范畴,增大切换成功率;飞机按照常规飞行,飞行方向变化符合正态分布时,切换成功率100%;但如果飞机在启动切换后提速过高,则可能造成此次切换失败,降低切换成功率;而且切换算法中的轨迹更新间隔不宜取过大,小于10s,否则降低切换成功率。更多还原

【Abstract】 Data Link technology is the outcome of informational military revolution. The one who has advanced data link technique can obtain the most advantage of the war. Therefore, all countries of the whole world are developing this technique for the technique storage of the army. Because Data Link, using wireless communication to transmit many kinds of data from front to back battlefield, can obtain more time for the war, so the future army makes it one of the most important technique to study. Two most primary characteristic of Data Link are real time transmission and seamless coverage. To ensure the seamless coverage of Air-ground Data Link system and continuous transition of data, the right handoff must be made before mobile node move out from the coverage area of fixed node. Therefore, the thesis mainly research on the handoff strategy in Air-ground Data Link system.At first, this thesis systemically analyze composing and working characteristics of Air-ground Data Link system, then handoff design process of mobile communications system is deeply studied, including control strategy, judge rule, algorithm and channel assignment rule of handoff. Aimed at air-ground data link system, a whole handoff scheme is designed. First, handoff is detected and controlled by control center. Secondly, handoff is judged by ground station from communication coverage area. Thirdly, based on the flying track and the different roles in the network of the mobile platform, four different kinds of algorithms are designed, including handoff time and the choice of next ground station. Fourthly, based on the working characteristics of Data Link system, the signaling after starting the handoff process is designed. After complete every algorithm, simply validate is made to ensure the algorithm usability.At last, to analyze the feasibility of these algorithms and characteristics of parameters, OPNET Modeler is used to simulate and test. This thesis simulates several parameters, such as Speed of mobile platforms, channel error ratio, update interval of track information and direction change of mobile platforms. And it is also analyzed the influence of some results, such as reservation of handoff time, handoff time and handoff success ratio. It is found that the simulation result and theory analyses are the same. If it is allowed in the network, then handoff success ratio can be increased by mobile platform being the master node. It belongs to soft-handoff. If mobile platform flies as normal, handoff success ratio would be 100%. But if after start handoff, mobile platform accelerate suddenly, it would reduce handoff success ratio. In these handoff algorithms, update interval of track information must be less than 10ms, or it would also reduce handoff success ratio.更多还原