A Performance Evaluation of NACK-Oriented Protocols as the Foundation of Reliable Delay- Tolerant Networking Convergence Layers

Delay-Tolerant Networking (DTN) is an active area of research in the space communications community. DTN uses a standard layered approach with the Bundle Protocol operating on top of transport layer protocols known as convergence layers that actually transmit the data between nodes. Several different common transport layer protocols have been implemented as convergence layers in DTN implementations including User Datagram Protocol (UDP), Transmission Control Protocol (TCP), and Licklider Transmission Protocol (LTP). The purpose of this paper is to evaluate several stand-alone implementations of negative-acknowledgment based transport layer protocols to determine how they perform in a variety of different link conditions. The transport protocols chosen for this evaluation include Consultative Committee for Space Data Systems (CCSDS) File Delivery Protocol (CFDP), Licklider Transmission Protocol (LTP), NACK-Oriented Reliable Multicast (NORM), and Saratoga. The test parameters that the protocols were subjected to are characteristic of common communications links ranging from terrestrial to cis-lunar and apply different levels of delay, line rate, and error

Delay/Disruption Tolerant Networking for the International Space Station (ISS)

Disruption Tolerant Networking (DTN) is an emerging data networking technology designed to abstract the hardware communication layer from the spacecraft/payload computing resources. DTN is specifically designed to operate in environments where link delays and disruptions are common (e.g., space-based networks). The National Aeronautics and Space Administration (NASA) has demonstrated DTN on several missions, such as the Deep Impact Networking (DINET) experiment, the Earth Observing Mission 1 (EO-1) and the Lunar Laser Communication Demonstration (LLCD). To further the maturation of DTN, NASA is implementing DTN protocols on the International Space Station (ISS). This paper explains the architecture of the ISS DTN network, the operational support for the system, the results from integrated ground testing, and the future work for DTN expansion

How Can Optical Communications Shape the Future of Deep Space Communications? A Survey

With a large number of deep space (DS) missions anticipated by the end of this decade, reliable and high capacity DS communications systems are needed more than ever. Nevertheless, existing DS communications technologies are far from meeting such a goal. Improving current DS communications systems does not only require system engineering leadership but also, very crucially, an investigation of potential emerging technologies that overcome the unique challenges of ultra-long DS communications links. To the best of our knowledge, there has not been any comprehensive surveys of DS communications technologies over the last decade. Free space optical (FSO) technology is an emerging DS technology, proven to acquire lower communications systems size, weight, and power (SWaP) and achieve a very high capacity compared to its counterpart radio frequency (RF) technology, the current used DS technology. In this survey, we discuss the pros and cons of deep space optical communications (DSOC). Furthermore, we review the modulation, coding, and detection, receiver, and protocols schemes and technologies for DSOC. We provide, for the very first time, thoughtful discussions about implementing orbital angular momentum (OAM) and quantum communications (QC) for DS. We elaborate on how these technologies among other field advances, including interplanetary network, and RF/FSO systems improve reliability, capacity, and security and address related implementation challenges and potential solutions. This paper provides a holistic survey in DSOC technologies gathering 200+ fragmented literature and including novel perspectives aiming to setting the stage for more developments in the field.Comment: 17 pages, 8 Figure

Experience with Delay-Tolerant Networking from Orbit

We describe the first use from space of the Bundle Protocol for Delay-Tolerant Networking (DTN) and lessons learned from experiments made and experience gained with this protocol. The Disaster Monitoring Constellation (DMC), constructed by Surrey Satellite Technology Ltd (SSTL), is a multiple-satellite Earth-imaging low-Earth-orbit sensor network in which recorded image swaths are stored onboard each satellite and later downloaded from the satellite payloads to a ground station. Store-and-forward of images with capture and later download gives each satellite the characteristics of a node in a disruption-tolerant network. Originally developed for the Interplanetary Internet, DTNs are now under investigation in an Internet Research Task Force (IRTF) DTN research group (RG), which has developed a bundle architecture and protocol. The DMC is technically advanced in its adoption of the Internet Protocol (IP) for its imaging payloads and for satellite command and control, based around reuse of commercial networking and link protocols. These satellites use of IP has enabled earlier experiments with the Cisco router in Low Earth Orbit (CLEO) onboard the constellation s UK-DMC satellite. Earth images are downloaded from the satellites using a custom IP-based high-speed transfer protocol developed by SSTL, Saratoga, which tolerates unusual link environments. Saratoga has been documented in the Internet Engineering Task Force (IETF) for wider adoption. We experiment with the use of DTNRG bundle concepts onboard the UK-DMC satellite, by examining how Saratoga can be used as a DTN convergence layer to carry the DTNRG Bundle Protocol, so that sensor images can be delivered to ground stations and beyond as bundles. Our practical experience with the first successful use of the DTNRG Bundle Protocol in a space environment gives us insights into the design of the Bundle Protocol and enables us to identify issues that must be addressed before wider deployment of the Bundle Protocol. Published in 2010 by John Wiley & Sons, Ltd. KEY WORDS: Internet; UK-DMC; satellite; Delay-Tolerant Networking (DTN); Bundle Protoco

Dynamic Code Selection Method for Content Transfer in Deep Space Network

Space communications feature large round-trip time delays (for example, between 6.5 and 44 minutes for Mars to Earth and return, depending on the actual distance between the two planets) and highly variable data error rates, for example, bit error rate (BER) of 10−5 is very comand even higher BERs on the order of 10−1 is observed in the deep- space environment. We develop a new content transfer protocol based on RaptorQ codes and turbo codes together with a real-time channel prediction model to maximize file transfer from space vehicles to the Earth stations. While turbo codes are used to correct channel errors, RaptorQ codes are applied to eliminate the need for negative-acknowledgment of the loss of any specific packet. To reduce the effect of channel variation, we develop a practical signal-to-noise ratio (SNR) prediction model that is used to periodically adjust the turbo encoder in distant source spacecraft. This new protocol, termed as dynamic code selection method (DCSM), is compared with two other methods: turbo based genie method (upper bound of DCSM performance) assuming that the channel condition is perfectly known in advance and a static method in which a fixed turbo encoder is used throughout a communication pass. Simulation results demonstrate that the genie can increase telemetry channel throughput expressed in terms of the total number of successfully delivered files during a communication pass by about 20.3 % and DCSM achieves more than 99 % of genie, compared to the static approach being used currently

Enabling E2E reliable communications with adaptive re-encoding over delay tolerant networks

Reliable end-to-end (E2E) communication in Delay Tolerant Network (DTN) is a challenging task due to long delay and frequent link disruptions. To enable reliability, the IETF is currently looking at strategies to integrate erasure coding mechanisms inside DTN architecture. The objective is to extend the ability of the existing DTN bundle fragmentation mechanism to support cases where bundles have a high probability of being lost. To date, discussions agree that an intermediate node can re-encode bundles, leaving all decoding process at the destination node in order to let intermediate node operations be as simple as possible. We propose to study and analyze possible re-encoding strategies at intermediate nodes using an on-the-fly coding paradigm. We also investigate how re-encoding and acknowledgment strategies based on this coding scheme would enable reliable E2E communication. Finally, we propose an adaptive mechanism with low complexity that deals with both re-routing events and network dynamics which are common in the context of DTN. Simulation results show that re-encoding at the relay and the adaptive mechanism allows a significant reduction in terms of network overhead injected by erasure codes while ensuring the E2E reliability

Small satellites and CubeSats: survey of structures, architectures, and protocols

The space environment is still challenging but is becoming more and more attractive for an increasing number of entities. In the second half of the 20th century, a huge amount of funds was required to build satellites and gain access to space. Nowadays, it is no longer so. The advancement of technologies allows producing very small hardware components able to survive the strict conditions of the outer space. Consequently, small satellites can be designed for a wide set of missions keeping low design times, production costs, and deployment costs. One widely used type of small satellite is the CubeSat, whose different aspects are surveyed in the following: mission goals, hardware subsystems and components, possible network topologies, channel models, and suitable communication protocols. We also show some future challenges related to the employment of CubeSat networks

Implementing Delay-Tolerant Networking at Morehead State University

A thesis presented to the faculty of the College of Science at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Science by Nathaniel J. Richard on April 28, 2017

Software Requirements Specification for Lunar Icecube

A thesis presented to the faculty of the College of Science at Morehead State University in partial fulfillment of the requirements for the Degree Master of Science by Michael R. Glaser-Garbrick on April 21, 2017