广域DGNSS信息大规模实时播发系统研究

实践证明广域DGNSS(Differential Global Navigation Satellite System，DGNSS)可有效提高定位精度和完好性,但在高层建筑物较多的城市或室内,由于建筑物对卫星信号遮挡严重,根本无法实现高精度定位导航,通过互联网播发增强信息,有其独特的优越性。通过研究基于互联网的广域DGNSS(IBWD)的系统组成,并设计了其网络结构。将i3组播和基于IP路由信息表的应用层组播相结合,构建了基于节点异构性的分层混合组播网络。分析IBWD的结构特点,建立其网络模型,结果显示,IBWD具有较好的实时性和可扩展性,可以很好地满足导航增强信息在互联网上播发的应用需求。

Research on Real Time Broadcasting System of Large Scale DGNSS Information

The wide area differential GNSS can be used to improve the accuracy, credibility and integrity of the navigation by broadcasting augmentation messages for receivers of the covering areas through geostationary earth orbit (GEO) satellites. But in cities with more building obstacles or in rooms, it is unable to realize the high accurate navigation. The way that the navigation augmentation messages are broadcast through internet has its unique advantages. The configuration and the network structure of internet-based wide area DGNSS (IBWD) are designed in this paper. According to node heterogeneity, the nodes that would join IBWD are classified into differential node types including proxy nodes and general nodes. The hierarchy mix multicast system based on node heterogeneity is constructed by the combination of application layer multicast where IP route information table is applied and i3 multicast. The results of simulation show that IBWD allows nodes to leave and join dynamically, and it is highly robust against failures. IBWD allows real time communication and the throughput of server is lower than other systems, so it can well meet the need of applications of large scale and real time broadcasting for the augmentation messages of GNSS through internet.