Delay and Disruption Tolerant Networking MACHETE Model

To verify satisfaction of communication requirements imposed by unique missions, as early as 2000, the Communications Networking Group at the Jet Propulsion Laboratory (JPL) saw the need for an environment to support interplanetary communication protocol design, validation, and characterization. JPL's Multi-mission Advanced Communications Hybrid Environment for Test and Evaluation (MACHETE), described in Simulator of Space Communication Networks (NPO-41373) NASA Tech Briefs, Vol. 29, No. 8 (August 2005), p. 44, combines various commercial, non-commercial, and in-house custom tools for simulation and performance analysis of space networks. The MACHETE environment supports orbital analysis, link budget analysis, communications network simulations, and hardware-in-the-loop testing. As NASA is expanding its Space Communications and Navigation (SCaN) capabilities to support planned and future missions, building infrastructure to maintain services and developing enabling technologies, an important and broader role is seen for MACHETE in design-phase evaluation of future SCaN architectures. To support evaluation of the developing Delay Tolerant Networking (DTN) field and its applicability for space networks, JPL developed MACHETE models for DTN Bundle Protocol (BP) and Licklider/Long-haul Transmission Protocol (LTP). DTN is an Internet Research Task Force (IRTF) architecture providing communication in and/or through highly stressed networking environments such as space exploration and battlefield networks. Stressed networking environments include those with intermittent (predictable and unknown) connectivity, large and/or variable delays, and high bit error rates. To provide its services over existing domain specific protocols, the DTN protocols reside at the application layer of the TCP/IP stack, forming a store-and-forward overlay network. The key capabilities of the Bundle Protocol include custody-based reliability, the ability to cope with intermittent connectivity, the ability to take advantage of scheduled and opportunistic connectivity, and late binding of names to addresses

Sistema de distribución del cambio de estado de semáforos hacia vehículos a través de una red oportunista

Actualmente, una gran cantidad de marcas automovilísticas y centros de investigación trabajan en el diseño y la fabricación de vehı́culos autónomos. Estos vehı́culos toman decisiones a partir de cámaras y sensores. En este trabajo se plantea crear un entorno que, mediante la utilización de redes tipo Delay and Disruption Tolerant Networking, proporcione información a los vehı́culos sobre el estado de los semáforos que se van a encontrar. Para ello, los semáforos envían la información solicitando que sea propagada por los vehículos que puedan estar dirigiéndose hacia los semáforos.Nowadays, many automobile brands and research centers work in the design and manufacture of autonomous vehicles. These vehicles make decisions from cameras and sensors. This article proposes to create an environment that provides information to vehicles Delay and Disruption Tolerant Networking (DTN). The main idea is to transmit the information of the change of state of the traffic lights to vehicles. In addition, it is suggested that vehicles can communicate with each other using DTN.Actualment, una gran quantitat de marques automobilístiques i centres d'investigació treballen en el disseny i la fabricació de vehicles autònoms. Aquests vehicles prenen decisions a partir de càmeres i sensors. En aquest treball es planteja crear un entorn que, mitjançant la utilització de xarxes tipus Delay and Disruption Tolerant Networking, proporcioni informació als vehicles sobre l'estat dels semàfors que es troben pel camí. Per a fer-ho possible, els semàfors envien la informació demanant que sigui distribuïda pels vehícles que poden estar anant cap als semàfors

09071 Abstracts Collection -- Delay and Disruption-Tolerant Networking (DTN) II

From 08.02. to 11.02.2009, the Dagstuhl Seminar 09071 ``Delay and Disruption-Tolerant Networking (DTN) II \u27\u27 was held in Schloss Dagstuhl~--~Leibniz Center for Informatics. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

A mobile code bundle extension for application-defined routing in delay and disruption tolerant networking

Grup de recerca SENDA (Security of Network and Distributed Applications)In this paper, we introduce software code to improve Delay and Disruption Tolerant Networking (DTN) performance. DTN is extremely useful when source and destination nodes are intermittently connected. DTN implementations use application-specific routing algorithms to overcome those limitations. However, current implementations do not support the concurrent execution of several routing algorithms. In this paper, we contribute to this issue providing a solution that consists on extending the messages being communicated by incorporating software code for forwarding, lifetime control and prioritisation purposes. Our proposal stems from the idea of moving the routing algorithms from the host to the message. This solution is compatible with Bundle Protocol (BP) and facilitates the deployment of applications with new routing needs. A real case study based on an emergency scenario is presented to provide details of a real implementation. Several simulations are presented to prove the feasibility and usability of the system and to analyse its performance in comparison to state-of-the-art approaches

More experiments with Delay and Disruption Tolerant Networking over AX.25 Networks

Previously the authors gave an overview of a Delay Tolerant Network Convergence Layer implemen- tation that operates over Connected Mode AX.25, and detailed the results of some performance tests using it to transfer data over Amateur Radio channels. These results were compared to both a native AX.25 and a TCP/IP- over-AX.25 implementation. The investigation of TCP/IP was undertaken because, while it is generally accepted that TCP is unsuited to wireless links, it has become the dominant protocol in real-world applications, with over 50% of internet traffic now accounted for by TCP over port 80 [1]. As some issues were highlighted in experiments leading to the authors’ prior publication, these have been worked on and have been largely resolved. It was also found that our model for an ideal AX.25 communications channel had deficiencies, so a correction is offered. Additionally, we also tested our Convergence Layer alongside a TCP/IP over AX.25 implementation on both a 1200 and 9600 baud point-to-point link and give comparative results between our Convergence Layer implementation and TCP/IP. Real-world behaviour of the data link still diverges from the model, but the authors provide some possible reasons for this

Experiments with Delay and Disruption Tolerant Networking in AX.25 and D-Star Networks

This paper examines the performance of DTN bundling layers against native protocols for radio data network with a view to possible deployment for emergency communications purposes. The authors conducted experiments with an existing DTN convergence layer in both AX.25 point-to-point and D-Star multi-hop communications links with hidden transmitters. The experimental results show that the DTN system exhibits marginally better performance than TCP/IP, appears to perform better where there are hidden transmitters, and has a more compact link utilisation pattern than TCP/IP. However, situations where obvious improvements can still be made were also identified

Review on free-space optical communications for delay and disruption tolerant networks

The increase of data-rates that are provided by free-space optical (FSO) communications is essential in our data-driven society. When used in satellite and interplanetary networks, these optical links can ensure fast connections, yet they are susceptible to atmospheric disruptions and long orbital delays. The Delay and Disruption Tolerant Networking (DTN) architecture ensures a reliable connection between two end nodes, without the need for a direct connection. This can be an asset when used with FSO links, providing protocols that can handle the intermittent nature of the connection. This paper provides a review on the theoretical and state-of-the-art studies on FSO and DTN. The aim of this review is to provide motivation for the research of an optical wireless satellite network, with focus on the use of the Licklider Transmission Protocol. The assessment presented establishes the viability of these networks, providing many examples to rely on, and summarizing the most recent stage of the development of the technologies addressed.info:eu-repo/semantics/publishedVersio

Conceptual Design of a Communication-Based Deep Space Navigation Network

As the need grows for increased autonomy and position knowledge accuracy to support missions beyond Earth orbit, engineers must push and develop more advanced navigation sensors and systems that operate independent of Earth-based analysis and processing. Several spacecraft are approaching this problem using inter-spacecraft radiometric tracking and onboard autonomous optical navigation methods. This paper proposes an alternative implementation to aid in spacecraft position fixing. The proposed method Network-Based Navigation technique takes advantage of the communication data being sent between spacecraft and between spacecraft and ground control to embed navigation information. The navigation system uses these packets to provide navigation estimates to an onboard navigation filter to augment traditional ground-based radiometric tracking techniques. As opposed to using digital signal measurements to capture inherent information of the transmitted signal itself, this method relies on the embedded navigation packet headers to calculate a navigation estimate. This method is heavily dependent on clock accuracy and the initial results show the promising performance of a notional system

Sviluppo di nuove funzioni per il supporto dell'algoritmo di routing OCGR nel simulatore ONE per reti DTN di tipo opportunistico

L'ambiente di ricerca di questa tesi è quello del Delay- and Disruption-Tolerant Networking (DTN), un'architettura di rete progettata per far fronte ai problemi che caratterizzano le cosiddette “challenged networks”: tempi di propagazione elevati, un alto tasso di pedita dei pacchetti e connessioni intermittenti. L'origine di questa architettura risiede nella generalizzazione dei requisiti identificati per Inter-Planetary Networking (IPN), una rete composta da sonde, stazioni spaziali e satelliti, ma sono state ampiamente studiate anche applicazioni terrestri come reti militari tattiche, reti di sensori, reti mobili ad-hoc etc.. Nelle comunicazioni nello spazio profondo i contatti tra i nodi sono deterministici (perché dovuti al moto dei pianeti e delle navicelle spaziali), a differenza delle reti terrestri nelle quali i contatti sono generalmente opportunistici (non noti a priori). Per tutte queste reti, l'impiego dei protocolli della suite TCP/IP risulta inefficace o inattuabile. Esistono diverse implementazioni dell'architettura DTN: DTN2, IBR-DTN e ION (Interplanetary Overlay Network), sviluppata da NASA/JPL, per applicazioni spaziali. All'interno di ION è presente l'algoritmo di routing detto Contact Graph Routing (CGR), progettato per operare in ambienti con connettività deterministica e una sua estensione per ambienti non deterministici detta Opportunistic Contact Graph Routing (OCGR). Per lo studio degli algoritmi di routing nelle reti DTN la “Helsinki University of Techology” ha sviluppato il simulatore “The ONE”, che implementa diversi modelli di moto, di generazione dei dati, e permette la visualizzazione in tempo reale tramite interfaccia grafica. L’obiettivo principale di questa tesi è stato quello di combinare in un unico pacchetto i contributi degli studenti dell’Università di Bologna che mi hanno preceduto lavorando sul tema dell’integrazione di CGR in The ONE