Communication Concepts for Self-Organizing Distributed Small Satellite Systems

空间飞行正面临着一种范式的转变：小型合作卫星组越来越被视为传统的整体卫星系统的一种有希望的替代办法。这使得特派团更加灵活，有了新的应用场景，同时降低了成本，提高了复原力，但同时需要新的、与实地最先进的技术相比复杂得多的沟通和协调机制。拟议的项目将为今后小型卫星合作系统的通信机制奠定基础。目标是一个强大的整体系统，使有效地利用通信带宽和能量，并可以处理和补偿（部分）故障。例如，卫星之间必须交换状态和位置信息，以节能方式将传感器数据传送到地面，并向卫星网络可靠地传送命令，该项目以地球观测领域的两种具体设想为出发点，重点研究这类系统中的通信协议设计问题。第一种情况考虑地球观测卫星的编队，即一组卫星保持相对接近并合作调整其方向。它们一起执行光学或磁性测量，并利用其位置偏移在多个位置或从不同角度进行同时测量。第二种情况是基于卫星星座，即，在空间上广泛分离的轨道上的卫星，其跟踪转发器的当前位置（例如，在火车、轮船或飞机上）。因此，这一设想有着明显不同但同样实用的要求，在这两种情况下，都将利用小型卫星网络的具体特点来提高通信效率。这些特征包括网络站点之间可预测的联系时间以及关于所获取数据的数量、来源和结构的知识。与其他领域相比，（太阳能）能源和其他资源的可用性和消耗也可以提前预测。这可以用于传输规划或卫星之间的协作数据聚合。所设计的协议和机制将通过模拟和实验进行分析评估。

Space flight is facing a paradigm shift: groups of small, cooperating satellites are more and more considered as a promising alternative to classical monolithical satellite systems. This allows for more flexible missions and new application scenarios, in combination with reduced cost and improved resilience, but at the same time demands new and - compared to the state of the art in the field - significantly more complex communication and coordination mechanisms. The proposed project will establish a basis for communication mechanisms in future systems of cooperating small satellites. The aim is a robust overall system which makes efficient use of communication bandwidth and energy and which can deal with and compensate (partial) faults. It is, for instance, necessary to exchange status and position information between satellites, to transfer sensor data to the ground in an energy-efficient way and to communicate commands reliably to the satellite network.The project uses two specific scenarios from the area of earth observation as a starting point and focuses on questions of communication protocol design in such systems. The first scenario considers a formation of earth observation satellites, that is, a group of satellites which stay relatively close together and cooperatively adjust their orientation. Together they perform optical or magnetical measurements and make use of their position offsets for simultaneous measurements at multiple locations or from different angles. The second scenario is based on a satellite constellation, i.e., satellites on spatially widely separated orbits, which track the current positions of transponders (e.g., on trains, ships or airplanes) in a vast area. This scenario therefore comes with significantly different, but nevertheless likewise practically relevant requirements.In both cases the specific characteristics of small satellite networks will be leveraged to increase the communication efficiency. These characteristics include predictable contact times between network stations and knowledge about the amount, origin and structure of aquired data. In comparison to other fields, the availability and consumption of (solar) energy and other resources can also be predicted well in advance. This can be used for transmission planning or for cooperative data aggregation between satellites. The designed protocols and mechanisms will be evaluated analytically, through simulations and in experiments.