Delay-tolerant networking: an approach to interplanetary Internet

TCP experiences severe performance degradation in cislunar communications because of some assumptions built into its design. Delay/disruption tolerant networking (DTN) is a class of network techniques that is developed to work over internet protocols to accommodate long link delay and frequent link disruptions in space communication environment. Most of the work concerning DTN protocols and techniques focused on its application in terrestrial wireless network and sensor-based networks. In this paper, we present an experimental evaluation of the DTN protocols with BP/TCPCL running on top of TCP/IP over a long-delay cislunar communication channel with and without link disruption. We hope the experiment results and analysis in this paper will apply equally well in any deep space mission with a round-trip time (RTT) that is comparable to that of the Earth-Moon system.

2010 IEEE Aerospace Conference, 2010

The University of Colorado is working with NASA to extend Earth's internet into outer space and across the solar system. The new networking technology is called Disruption Tolerant Networking (DTN), and is being tested on the International Space Station. DTN will enable NASA and other space agencies around the world to better communicate with international fleets of spacecraft that will be used to explore the moon and Mars. This technology is evolving into an Interplanetary Internet.

2nd ERCIM Workshop on …, 2008

We propose Delay-Tolerant Transport Protocol (DTTP) to address reliable data transfer in stressed network environments, such as space communications. Since existing TCP mechanisms do not work well (or at all) for such networks, new transport schemes are required. Intermittent connectivity in space environments calls for new transport approaches that smoothly adapt to the special networking conditions. DTTP is primarily a transport layer protocol and satisfies the inherent architecture requirements of Delay Tolerant Networking (DTN) in the absence of IP network infrastructure. It allows for reliable, efficient data transfer offering a number of application-oriented transmission strategies. Otherwise, when an IP architecture exists, DTTP operates as a standalone transport entity which interfaces with IP directly. We introduce the protocol's properties and functionality that enable its deployment in challenged networks. We conduct simulations that demonstrate the protocol's efficiency in scenarios with: (i) long propagation delays, (ii) minimum to relatively high packet error-rate, and (iii) intermittent connectivity.

International Journal On Advances in Internet Technology, 2010

Abstract: In the last few years deep space exploration missions are undergoing a significant transformation as are the expectations of their scientific investigators and the public who participate in these experiences. National Aeronautics and Space Administration (NASA) and European Space Agency (ESA), recently, decided pursuing a mission to study Jupiter and its moons, and another to visit the largest moons of Saturn. Those missions need new communication and networking infrastructures able to support space exploration, to ...

2012

A concept for inter-planetary communications is proposed. The concept employs three polar orbiting satellites around the sun and a combination of geosynchronous and polar orbiting satellites around planets of interest in the solar system. The key aspect of this concept is that it assures a continuous communication connection between two objects within the solar system, be it a spacecraft or a planet. The orbital aspects of this concept are described, estimates of the propagation delays are provided and a protocol for exchanging and maintaining solar time is discussed. In addition, a RF communications link budget assessment is made and the expected performance presented. Performance areas where design trades need to be performed and a few enabling technologies are briefly discussed.

2008

Designing efficient transmission mechanisms for advanced satellite networks is a demanding task, requiring the definition and the implementation of protocols and architectures well suited to this challenging environment. In particular, transport protocols performance over satellite networks is impaired by the characteristics of the satellite radio link, specifically by the long propagation delay and the possible presence of segment losses due to physical channel errors. The level of impact on performance depends upon the link design (type of constellation, link margin, coding and modulation) and operational conditions (link obstructions, terminal mobility, weather conditions, etc.). To address these critical aspects a number of possible solutions have been presented in the literature, ranging from limited modifications of standard protocols (e.g. TCP, transmission control protocol) to completely alternative protocol and network architectures. However, despite the great number of dif...

Acta Astronautica, 2003

Int'l J. of Communications, Network and System Sciences, 2011

The throughput of conventional transport protocols suffers significant degradation with the increased Round Trip Time (RTT) typically seen in deep space communication. This paper proposes a Delay Resistant Transport Protocol (DR-TCP) for point-to-point communication in deep space exploration missions. The issues related to deep space communication protocol design and the areas where modifications are necessary are investigated, and a protocol is designed that can provide good throughput to the applications using a deep space link. The proposed protocol uses a cross layer based approach to find the allocated bandwidth and avoids initial bandwidth estimation. A novel timeout algorithm estimates the timeout duration with an objective to maximize throughput and avoid spurious timeout events. The protocol is evaluated through extensive simulations in ns2 considering high RTT values typically seen in Lunar and Mars Exploration Networks under different conditions of packet error rates. DR-TCP provides a significant increase in the throughput as compared to traditional transport protocols under the same conditions. A novel adaptive redundant retransmission algorithm is also presented to take care of the high PER in deep space links. The effect of the Retransmission Frequency has been critically analyzed considering both Lunar and Deep Space scenarios under different levels of PER. The results are very encouraging even in high error conditions. The protocol exhibits a RTT independent behavior in throughput, which is the most desirable quality of a protocol for deep space communication.

Acta Astronautica, 2010

We present Delay-Tolerant Transport Protocol (DTTP) which enables fast and reliable communications in deep space. The proposed protocol regularly measures its performance through available paths towards destination, and develops its routing strategy accordingly. We evaluate DTTP performance across a wide range of network scenarios that pertain to Mars-to-Earth distances. Based on simulation results, we show that: (i) delay-tolerant networking does not necessarily imply belated communications; (ii) DTTP can efficiently support reliable data transfers in challenged networks; and (iii) dynamic routing is feasible in space.

Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 2009

As the number and complexity of space missions increases, space communications enter a new era, where internetworking gradually replaces or assists traditional telecommunication protocols. The Delay Tolerant Network (DTN) architecture has recently emerged as a communication system for challenged networks, originally designed for the Interplanetary Internet. In the context of our project with ESA called "Extending Internet into Space -ESA DTN Testbed Implementation and Evaluation" we intend to deploy a distributed, flexible and scalable DTN testbed for space communications. The testbed will provide the supportive infrastructure for the design and evaluation of space-suitable DTN protocols, architectures, and routing policies to allow efficient deep-space communications. Throughout the project, we will demonstrate the operational capabilities of the DTN protocols in space; design and evaluate novel transport protocols and architectures for reliable data transfer in space; and investigate routing algorithms that comply with ESA's policies and resource status.