Energy-efficient routing in LEO satellite networks for extending satellites lifetime

Low Earth Orbit (LEO) satellites, when exposed to the sun, use solar energy for operation, processing, and communication, and with excess energy they recharge their batteries. However, when satellites are in an area with no sunlight, called eclipse areas, they operate using only their battery power. The batteries have limitations on the amount of recharges/discharges, also known as the depth of discharge (DOD) cycle. Therefore, this restricts the useful life of the batteries themselves and also of the satellites. In this paper, we propose two different efficient routing methods for LEO satellite networks, which optimize traffic in order to reduce the DOD of satellites. We improved the Energy and Capacity Aware Routing (ECARS) metric, existing in the literature, by adding the Energy Routing prUning (ERU)-DOD and Energy Routing penAlty (ERA)-DOD methods. These proposed methods prune and penalize, respectively, the links whose satellites have reached a certain minimum battery charge threshold. With this procedure, we avoid over-discharging the satellites' battery, and thus, the lifetime is extended. Simulations results show that ERU-DOD and ERA-DOD can increase 133.19% and 11.88% the satellites' batteries lifetime, respectively. Moreover, when comparing our ERU-DOD and ERA-DOD proposals with the ECARS in terms of the average residual energy of the batteries, they provide an increase of 109.77% and 32.73%, respectively. In addition, ERU-DOD and ERA-DOD proposals showed a gain in throughput of 7.28% and 3.06% higher than ECARS. Furthermore, compared to the ECARS metric, the ERA-DOD proposal has a 1.1% lower delay, a 1.5% lower number of hops, and 0.49% less in the total of blocked sources.