低轨卫星星座物联网业务量建模

随着物联网(IoT)规模的不断发展，其业务需求呈现出多样化、全球化的趋势。针对地面物联网无法覆盖全球的缺点，卫星物联网尤其是低轨卫星星座(LEOSC)物联网可以有效地为地面物联网提供覆盖性能上的补充和延伸。由于低轨卫星星座物联网系统广覆盖、高动态的特点，其业务量统计特性需要考虑到环境因素造成的影响，这导致其业务量分布与地面物联网存在显著差异。从合理高效利用星上有限资源角度出发，该文研究基于低轨卫星星座的全球物联网业务模型。结合多样化的业务特点以及卫星通信系统特性，采用统计建模理论，得出了全球物联网业务模型框架。并且初步提出了一种基于最高优先级的接入策略，以供设备节点实时选择接入的卫星。仿真结果表明:泊松过程可以用于近似模拟低轨卫星物联网中大量存在的异步流量的叠加过程；由于低轨卫星具有高动态性，其业务源高速变化，导致了卫星业务忙闲不均，峰均比(PAR)较高。

Traffic Modeling for Low Earth Orbit Satellite Constellation Internet of Things

With the continuous development of the Internet of Things(IoT), its business demands show a trend of diversification and globalization. As the ground Internet of Things can not cover the whole world, the satellite IoT, especially the Low Earth Orbit Satellite Constellation (LEOSC) IoT, can supplement and extend the ground network. Due to the wide coverage and high dynamic characteristics of the LEOSC IoT system, there are significant differences between it and the ground IoT in terms of traffic statistics. In order to make reasonable and efficient use of limited resources on board, the traffic model of global Internet of Things based on LEOSC is studied in this paper. Combined with diversified traffic characteristics and satellite communication system characteristics, the framework of global IoT traffic model is obtained by using statistical modeling theory. What’s more, an access strategy based on the highest priority is proposed to enable the device node to select the satellite in real time. The simulation results show that the Poisson process can be used to simulate approximately the superposition process of asynchronous traffic commonly exist in LEOSC IoT, and due to the high dynamic nature of low earth orbit satellite, its traffic source changes at high speed, resulting in high Peak-to-Average Ratio(PAR) of traffic.