Timely Reliability of Leo Satellite Communication Systems Considering Connectivity and Timeliness

Owing to the advantages of global coverage, high flexibility and low cost, low earth orbit (LEO) satellite communication systems have become the most promising communication mode. However, it is difficult to accurately assess the connectivity and timeliness of end-to-end (e2e) transmission due to the high traffic load/congestion caused by long-distance transmission and randomness of relative position caused by satellite movement. In this work, for the scenario of two remote ground ends communicating via LEO satellites, we develop analysis models to analyze the connectivity and various delays of the e2e link, and propose a timely reliability metric for the e2e link to measure its ability to transmit data timely and reliably. Specifically, considering the randomness of LEO satellite's position relative to the ground end, the probability density function (PDF) of their distance is derived. Then, based on the randomness of distances and channels of the e2e link, analytical expressions are derived for the connectivity probability and e2e delay using the queueing theory and numerical computation methods. Thirdly, the timely reliability assessment method is proposed for the e2e link considering the connectivity and timeliness. Finally, numerical results for LEO satellite communication systems are presented to validate the proposed analytical model.