Delay Tolerant Network (DTN) over asymmetric cislunar communication channels.

摘要

The National Aeronautics and Space Administration (NASA) has been using internet-type protocols for conducting space communication, but the inherent design of Transmission Control Protocol (TCP) makes its performance degrade in space. So NASA's Jet Propulsion Lab has developed an advanced networking technology named Delay Tolerant Networking (DTN) for effective space communication. DTN can overcome the limitations of TCP-based protocols including frequent link disruption and high error rates. Interplanetary Overlay Network (ION) is an implementation of DTN designed to reduce cost and risk in space communication by simplifying its design and working over space links, terrestrial links, and planetary links. This DTN implementation is intended to function in an interplanetary network environment, where it will always face two design constraints: link constraints and processor constraints. The wireless links used in actual interplanetary space communication are usually slow and asymmetric. In this thesis, we present an experimental investigation of ION protocols including TCPCL/TCP/IP, LTPCL/UDP/IP, and their hybrid by conducting file transfer experiments over a network test bed with various asymmetric channel ratios. One major conclusion is that the hybrid combination of the protocols has significant goodput advantage over the other two protocols as the ratio of data channel rate to ACK channel rate increases.