A major problem for low Earth orbit (LEO) constellations with intersatellite links is the efficient routing of the data packets through such a highly dynamic network. In order to achieve a worldwide coverage even in remote areas and Internet access with a limited amount of gateway stations, intersatellite links are a promising approach. Since LEO constellations represent a distinct, highly dynamic routing environment, specific strategies are needed. To this end, a suitable geographical routing scheme is proposed and investigated in two Walker Star constellations. The proposed scheme targets reliable transmissions with low latency and high data rates. The approach is based on a geographical address identifier in Layer 2 of the communication stack. The globe is thus divided into geographical areas that determine this identifier in the MAC address of the terminals. As mobile terminals are considered, the MAC addressing scheme is flexible, whereas the IP addresses of the terminals remain static. This decoupling allows for flexibility in the choice of the address resolution scheme. Moreover, the geographical identifier in the MAC address enables fast routing table lookups and switching. The proposed routing scheme also takes possible overloads of the satellites due to traffic into account and applies a rerouting procedure. When a packet arrives in the geographical area of the destination terminal, a local rerouting scheme is applied if needed. The proposed approaches take handover events that possibly occur during a transmission into account. Furthermore, the scan angles of the satellites have been adapted to the constellations to provide full coverage and high elevation angles. So a robust and adaptable routing scheme is provided for a dynamic environment where satellites and terminals are constantly moving. The proposed definitions and procedures have been implemented in a system level simulator, which allows for comparisons with adjustable parameters in various scenarios. In this work, an Iridium‐like constellation and a megaconstellation are investigated and compared regarding the address resolution procedures, the average end‐to‐end transmission delay, and the dropping and rerouting rates. Additionally, the signaling overhead is compared with other approaches. The simulator and results of the simulations provide grounds for further research w.r.t. the routing in satellite constellations using intersatellite links.

中文翻译：

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使用星际链路为低地球轨道卫星星座实现地理路由方案

带有星际链路的低地球轨道（LEO）星座的主要问题是如何通过这种高度动态的网络有效地路由数据包。为了即使在偏远地区和网关站数量有限的Internet访问中也要实现全球覆盖，卫星间链路是一种有前途的方法。由于LEO星座代表独特的，高度动态的路由环境，因此需要特定的策略。为此，提出了一种合适的地理路由方案，并在两个Walker Star星座中进行了研究。所提出的方案针对具有低等待时间和高数据速率的可靠传输。该方法基于通信堆栈的第2层中的地理地址标识符。因此，将地球划分为确定该终端的MAC地址中的此标识符的地理区域。当考虑移动终端时，MAC寻址方案是灵活的，而终端的IP地址保持静态。这种解耦可以灵活选择地址解析方案。此外，MAC地址中的地理标识符可实现快速的路由表查找和交换。所提出的路由方案还考虑了由于业务量造成的卫星过载，并应用了重新路由程序。当分组到达目的地终端的地理区域时，如果需要，则应用本地重路由方案。所提出的方法考虑了在传输期间可能发生的切换事件。此外，卫星的扫描角度已经适应了星座，以提供完整的覆盖范围和高仰角。因此，为卫星和终端不断移动的动态环境提供了一种健壮且适应性强的路由方案。提议的定义和过程已在系统级模拟器中实现，该模拟器可在各种​​情况下与可调参数进行比较。在这项工作中，研究了一个铱星星座和一个巨型星座，并就地址解析程序，平均端到端传输延迟以及掉线和重路由速率进行了比较。另外，将信令开销与其他方法进行比较。仿真器及其仿真结果为进一步的研究奠定了基础