Deep space autonomous network using reverse channel for congestion control

The extremely long propagation delay between interplanetary nodes poses challenges to the investigation of Store-and-forward Deep Space Autonomous Network (DSAN). Long propagation delay combined with scarcity of energy at the planetary wireless nodes and relays, introduces new dimensions to the congestion control challenge. In this paper, we take advantage of long propagation delay between nodes and propose a novel approach for congestion control. The long delayed channel can be utilized as a memory resource. Instead of dropping the packets due to lack of storage at the intermediate nodes such as satellite or a robotic spacecraft, they are transmitted back to the source. This significantly reduces packet loss, and lowers the per packet energy consumption. In addition, this method provides feedback on the congestion status of the relay node. Consequently, the source is able to dynamically control traffic flow in the source-relay channel until congestion is abated. Two proposed protocols, i.e., (i) reverse channel (without rate control) and (ii) reverse channel with rate control are investigated, and compared with a conventional protocol where no reverse channel is utilized. Extensive simulations are conducted which validate that the performance with reverse channel, especially reverse channel with rate control, far outweigh the conventional approach, in terms of energy consumption, and retransmission per successful packet.