Distributed Probabilistic Congestion Control in LEO Satellite Networks

Satellite communication in Low Earth Orbiting (LEO) constellations is an emerging topic of interest. Due to the high number of LEO satellites in a typical constellation, a centralized algorithm for minimum-delay packet routing would incur significant signaling and computational overhead. We can exploit the deterministic topology of the satellite constellation to calculate the minimum-delay path between any two nodes in the satellite network. But that does not take into account the traffic information at the nodes along this minimum-delay path. We propose a distributed probabilistic congestion control scheme to minimize end-to-end delay. In the proposed scheme, each satellite, while sending a packet to its neighbor, adds a header with a simple metric indicating its own congestion level. The decision to route packets is taken based on the latest traffic information received from the neighbors. We build this algorithm onto the Datagram Routing Algorithm (DRA), which provides the minimum delay path, and the decision for the next hop is taken by the congestion control algorithm. We compare the proposed congestion control mechanism with the existing congestion control used by the DRA via simulations, and show improvements over the same.