Delay performance comparison across seven Low-Earth-Orbit (LEO) satellite constellations

We carry out the thoughtful investigations on the end-to-end delay comparison based on seven proposed low-earth-orbit (LEO) satellite constellations, i.e., GlobalStar, Iridium, TeleSat, Kuiper, StarLink, OneWeb with 720 and 1764 satellite nodes, which include two major constellation types-polar and inclined orbits. The discussion focuses on the future satellite operation in space by gradually increasing the number of satellites nodes and analyzes the impact of the constellation scale on the performance of the inter-communication delay. The shortest path algorithm is used to simulate both international (Beijing to New York) and domestic (Beijing to Chengdu) scenarios for each constellation to calculate the shortest transmission delay and its corresponding hop count. Our results show that with the expansion of the number of satellites, the end-to-end delay could touch the floor. The optimized delay is achieved when the number of satellites is close to 1000 for both international and domestic scenarios, which values are 44ms and 6ms, respectively. There is no impressive improvement on the delay performance when further expanding the constellation scale. Moreover, as the number of satellites continue to accumulate, both the long-distance and short-distance communication scenarios, the large-scale star chain clusters aggravate the frequency of inter-star switching, easily leading to unstable transmission delay, which is not conducive to obtaining the best delay benefits. Therefore, for the delay performance-driven service, it is necessary to reasonably optimize the constellation structure to meet the user's communication needs through the appropriate number of satellites in the constellation.