Orbital Edge Computing: Nanosatellite Constellations as a New Class of Computer System
Orbital Edge Computing: Nanosatellite Constellations as a New Class of Computer System
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DOI：
10.1145/3373376.3378473
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发表时间：
2020-03
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影响因子：
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通讯作者：
Bradley Denby;Brandon Lucia
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作者：
Bradley Denby;Brandon Lucia
超小型卫星技术的进步和进入空间的成本的下降促使在低地球轨道出现了大型的装有传感器的卫星星座。其中许多卫星系统都是在一种“卫星管道”结构下运行的，即地面站向轨道发送命令，卫星用原始数据进行回复。在这项工作中，我们观察到，地球观测卫星的一个管道架构打破了星座人口的增加。随着时间的推移，通信受到系统的物理配置和约束的限制，例如地面站位置，纳米卫星天线尺寸和在轨道上收集的能量。我们定量地表明，纳米卫星星座的能力是由物理系统的限制。我们提出了一个轨道边缘计算（OEC）架构，以解决一个并行管道架构的局限性。OEC支持每个配备相机的纳米卫星的边缘计算，以便在无法下行时可以在本地处理感测数据。为了解决边缘处理延迟，OEC系统将卫星星座组织成计算流水线。这些管道基于地理位置并行数据收集和数据处理，而无需交叉链路协调。OEC卫星通过运行时服务显式地对物理环境的约束进行建模。该服务使用轨道参数、物理模型和地面站位置来触发数据收集、预测能源可用性并为通信做好准备。我们表明，与管道架构相比，OEC架构可以将地面基础设施减少24倍以上，并且管道可以将系统边缘处理延迟减少617倍以上。
Advances in nanosatellite technology and a declining cost of access to space have fostered an emergence of large constellations of sensor-equipped satellites in low-Earth orbit. Many of these satellite systems operate under a "bent-pipe" architecture, in which ground stations send commands to orbit and satellites reply with raw data. In this work, we observe that a bent-pipe architecture for Earth-observing satellites breaks down as constellation population increases. Communication is limited by the physical configuration and constraints of the system over time, such as ground station location, nanosatellite antenna size, and energy harvested on orbit. We show quantitatively that nanosatellite constellation capabilities are determined by physical system constraints. We propose an Orbital Edge Computing (OEC) architecture to address the limitations of a bent-pipe architecture. OEC supports edge computing at each camera-equipped nanosatellite so that sensed data may be processed locally when downlinking is not possible. In order to address edge processing latencies, OEC systems organize satellite constellations into computational pipelines. These pipelines parallelize both data collection and data processing based on geographic location and without the need for cross-link coordination. OEC satellites explicitly model constraints of the physical environment via a runtime service. This service uses orbit parameters, physical models, and ground station positions to trigger data collection, predict energy availability, and prepare for communication. We show that an OEC architecture can reduce ground infrastructure over 24x compared to a bent-pipe architecture, and we show that pipelines can reduce system edge processing latency over 617x.