On routing for extending satellite service life in LEO satellite networks

We address the problem of routing for extending the service life of satellites in Iridium-like LEO constellations. Satellites in LEO constellations can spend over 30% of their time under the earth's umbra, time during which they are powered by batteries. While the batteries are recharged by solar energy, the depth of discharge they reach during eclipse significantly affects their lifetime - and by extension, the service life of the satellites themselves. For batteries of the type that power Iridium satellites, a 15% increase to the depth of discharge can practically cut their service lives in half. We present two new routing metrics - LASER and SLIM - that try to strike a balance between performance and battery depth of discharge in LEO satellite constellations. Our basic approach is to leverage the deterministic movement of satellites for favoring routing traffic over satellites exposed to the sun as opposed to the eclipsed satellites, thereby decreasing the average battery depth of discharge - all without adversely affecting network performance. Simulations show that LASER and SLIM can reduce the depth of discharge by about 11% and 16%, respectively, which can lead to as much as 100% increase in the satellite batteries lifetime. This is accomplished by trading off very little in terms of end-to-end delay.