Optimal Download of Dynamically Generated Data by Using ISL Offloading in LEO Networks

With the growing demand for satellite network technology in military and commercial applications, a large number of LEO(Low Earth Orbit) satellites have been launched in various countries around the world. One of the most important tasks is to download the data collected by these satellites to the Earth Stations(ESs) for processing. Previous research efforts have focused on how to download satellite-collected data to ESs. They didn't consider the situation that the satellites continuously collect data when downloading data. In this paper, our goal is to optimize the data download from the satellites to the ES in the case of dynamic collection of satellite data. We use inter-satellite links (ISLs) to offload data from heavily loaded satellites to the light ones. We build a topology map based on the interaction time between satellites and the interaction time between the satellite and the ES, and allocate the download time to the satellite carrying the largest amount of data. Then, the time slice is dynamically divided and the inter-satellite scheduling is determined by a way of classifying the idle satellites. Finally, the maximum flow algorithm is applied to determine the specific inter-satellite transmission scheme. In this way, the ES idle time is minimized. Simulations results show that our solution can greatly improve the data download efficiency from the satellites to the ES.