Optimizing the Delay and Reliability of Low Altitude Satellite Network Topologies

This paper considers the effects on propagation delay and connectivity of changing the altitude and topology characteristics of a low altitude satellite network. A low altitude satellite network is assumed to be a system of satellites with altitudes in the range 2000 to 15000 km, such that any pair of satellites can exchange messages unless the line of sight between the satellites is blocked by the earth. A topology model is defined which uses equally spaced satellites at a single minimum altitude such that all points on the earth are visible by at least one satellite at all times. Propagation delays between arbitrary points on the earth are used in a delay metric to minimize the delay for specified altitudes or satellite count. The reliability criteria used include node connectivity, link connectivity, and ground coverage loss due to multiple satellite failures.