This paper surveys the most popular random access (RA), demand assignment (DA), and hybrids schemes for satellite broadband access networks. In addition, we present some recent research results we obtained when a reliable transmission control protocol, i.e. TCP, is coupled with the most promising RA methods foreseen in the second generation of DVB-RCS standard. In fact, the necessity to support a wider range of IP-based traffic, as in the case either of Supervisory Control And Data Acquisition (SCADA) systems or Machine-to-Machine (M2M) communications, fosters the introduction of random access schemes for information transport able to cope with large network sizes and low duty cycle bursty traffic with frequent inactivity periods on the return link. As an indication of future research aspects we also offer, in the conclusions section, a list of items to be investigated so that satellite can become integral part of the Future Internet.

Delay tolerant networking (DTN) is an emerging technology introduced for deep-space communications to address both very large propagation delay or link disruptions. The DTN paradigm results promising in several satellitebased scenarios where either physical or service interruption might be experienced. This paper focuses on a set of selected satellite-based scenarios, where the DTN paradigm adoption greatly improves the unicast and multicast communications' performance with limited costs in terms of both software add-ons and architectural modifications.

Il Rapporto di Avanzamento Tecnico fornisce la descrizione dei risultati realizzati relativi al SAL in esame (SAL 1) e tutte le informazioni necessarie alla verifica del raggiungimento degli obiettivi del SAL. Fornisce inoltre la pianificazione delle attività a finire evidenziando l'avanzamento dei pacchi di lavoro, le eventuali criticità e le relative azioni correttive proposte, nonchè le variazioni alla distribuzione dei costi e alla previsione temporale dei SAL che dovessero ritenersi necessarie alla realizzazione del programma e che si intende sottoporre all'attenzione dell'Amministrazione.

This technical report evaluates the performance of a NACK-oriented reliable multicast (NORM) transport protocol, when used in vehicular disruption-tolerant networks (vDTN). Comparisons are made between multicast transmissions with and without interleaver when NORM is used in "confirmed delivery" mode in order to assess reliable data delivery. Also, the performance evaluation of an efficient multicast file delivery, which advantage of a Cloud-based distributed file storage is provided.

This paper presents a performance study relative to the coupling of the Transmission Control Protocol (TCP) with the Contention Resolution Diversity slotted aloha (CRDSA) protocol, in the case of greedy TCP connections (also called elephants) on Digital Video Broadcasting-Return Channel via a geostationary satellite. CRDSA, which takes advantage of interference cancellation algorithms for collision/contention resolution, has already exhibited interesting performance when the power levels of all received bursts are perfectly balanced. In this paper, we extend the study to a more realistic case, where a certain spreading of the bursts' power levels is taken into account. The consequent capture effect even facilitates the collision resolution mechanism and yields an improvement in the overall TCP performance with respect to the balanced case. Furthermore, in certain conditions, the adoption of packet level forward error correction allows achieving even higher peaks of throughput than the expected ones. Copyright © 2014 John Wiley & Sons, Ltd.

The goal of this work was to understand the direction of the emerging web technologies and to evaluate their expected impact on satellite networking. Different aspects have been analysed using both real satellite testbeds and emulation platforms in different test sites in Europe. This analysis included an evaluation of the SPDY protocol performance over satellite and experiments to understand the expected interaction with PEPs (including scenarios with a SPDY proxy at a satellite gateway), the impact of security, and the effect of satellite capacity allocation mechanisms. The analysis also considered the impact of application protocols and the delay induced by end-system networks, such as a satellite-connected WiFi network.

L'architettura logica-funzionale di Easy Rider fu definita con l'obiettivo di assicurare una forte compatibilita? e capacita? di integrazione con le architetture di altri progetti Industria 2015. Di conseguenza, i requisiti, gli elementi funzionali, e le funzioni di Easy Rider furono specificati in riferimento al modello ARTIST [1], che e? l'architettura generale di riferimento per l'Italia per progetti industriali di Infomobilita? e non solo. La definizione dell'architettura parte dalla raccolta dei requisiti utente di Easy Rider da parte del Gruppo di Coordinamento Tecnico, in collaborazione con i responsabili dei quattro sottoprogetti. Questi requisiti furono specificati, fin dove possibile, in accordo con la nomenclatura ARTIST; ulteriori requisiti, non inclusi in ARTIST, furono aggiunti. Si fa notare in proposito che, a differenza di Easy Rider, ARTIST non e? pensato esclusivamente per servizi di Infomobilita?. Seguendo il modello di ARTIST, sulla base dei requisiti raccolti, si e? proceduto a definire le aree funzionali, le funzioni, i terminatori, ed i flussi funzionali. La specifica iniziale dell'architettura di Easy Rider ha fornito, quindi, un modello astratto in grado di catturare il maggior numero di processi informativi che si intendeva modellare in Easy Rider. Data la dimensione e la complessita? del progetto Easy Rider, il processo di specifica dell'architettura funzionale doveva seguire un processo evolutivo che, in piu? fasi, avrebbe raffinato i risultati iniziali per giungere progressivamente ad una specifica di dettaglio. Le ben note vicende del progetto hanno interrotto la stesura della parte di architettura funzionale. Per questo motivo il documento rappresenta una fotografia dell'architettura funzionale a 9 mesi dell'inizio del progetto, come era nella sua versione originale.

In this paper, we propose a realistic architecture for the integration between wireless sensor and satellite networks, covering technological issues from the access layer up to the transport and session layers, when uncorrelated sensor sources generate measurements' data. These data are multiplexed by a satellite gateway before being encapsulated and delivered through TCP/IP flows. This work aims at investigating the convenience, in terms of access delay and employed resources, in using the new random access methods based on successive interference cancellation, while guaranteeing the same throughput performance of the demand assignment multiple access systems. Moreover, this is the first work that provides a queue analysis of a satellite random access technique compared with dedicated access techniques with both short- and long-lived elastic connections.

Owing to the variety of traffic profiles that Machine to Machine (M2M) and Internet of Things (IoT) applications may generate, this work studies the applicability of a DVB-RCS2 gateway when clusters of sensor nodes exchange data via satellite toward a central operational control station via TCP/IP connections. We propose a realistic architecture for the integration between wireless sensor and satellite networks, by covering technological issues from access layer up to transport and session layers. In this scenario, uncorrelated sensor sources generate measurements, which are multiplexed by a satellite gateway, before being encapsulated and delivered through TCP/IP flows. According to the traffic nature and the access methods in the DVB terminal, the suitability of a random access method in place of a dedicated one is an open issue, when throughput and delivery delay are the performance metrics at the transport layer. This work aims at investigating when the new random access methods, based on successive interference cancellation, are convenient with respect to dedicated access methods. The comparison is made in terms of access delay and employed resources, while the throughput is guaranteed comparable to the one obtained by using demand assignment multiple access systems. We outline that this is the first work that provides a queueing analysis for the comparison between random and dedicated satellite access techniques, when used by both short and long-lived TCP connections.

This document includes the last achievements coming from research activities related analysis of new web paradigms, namely HTTP2.0 and SPDY, over scenarios including satellite. It is a follow-up of sub-tasks 3.1 and 3.2 [AD-1][AD-2], where performed analysis and experiments are enhanced and presented in forms of recommendation. With reference to [AD-2], achieved results have been analysed by each involved partner in order to report a detailed analysis and, when possible, models related to page download statistics, transmission scheduling, SPDY implications on current satellite performance and on future satellite system design.

This paper is not a survey related to generic wireless sensor networks (WSNs), which have been largely treated by Akyildiz et al. in [1], and later in a number of survey papers addressing more focused issues; rather, it specifically addresses architectural aspects related to WSNs in some way connected with a satellite link, a topic that presents challenging interworking aspects. The main objective is to provide an overview of the potential role of a satellite segment in the future wireless sensor networks. In this perspective, requirements of the most meaningful WSN applications have been drawn and matched to characteristics of various satellite/space systems in order to identify suitable integrated configurations.

The increasing complexity of Web contents, jointly with the growing diffusion of mobile nodes using wireless and satellite links to provide network connectivity, ignited the creation of new protocols. In this perspective, this paper evaluates the feasibility of using SPDY to increase the performance of Web data over broadband geostationary satellites. To this aim, we developed a set of tools to perform trials on a real satellite platform. Results show how SPDY allows getting rid of the HTTP acceleration part deployed within the Performance Enhancing Proxy (PEP), thus reducing both the complexity (e.g., in terms of TCP connections) and the development costs experienced by the service provider.

This paper presents a performance study relative to the coupling of the Transmission Control Protocol (TCP) with the franco.davoli@unige.it Contention Resolution Diversity Slotted Aloha (CRDSA) protocol, in the case of greedy TCP connections (also called elephants) on Digital Video Broadcasting-Return Channel via Satellite. CRDSA, which takes advantage of interference cancellation algorithms for collision/contention resolution, has already exhibited an interesting performance when the power levels of all received bursts are perfectly balanced. In this paper, we extend the study to a more realistic case that sees a certain spreading of the bursts' power levels. The consequent capture effect even facilitates the collision resolution mechanism and the overall TCP performance results improved with respect to the balanced case. Furthermore, in certain conditions, the adoption of packet level Forward Error Correction (FEC) allows handling system loads higher than the expected ones.

The increasing complexity of Web contents, jointly with the growing diffusion of mobile nodes using wireless and satellite links to provide network connectivity, ignited the creation of new protocols. In this perspective, this paper evaluates the feasibility of using SPDY to increase the performance of Web data over broadband geostationary satellites. To this aim, we developed a set of tools to perform trials on a real satellite platform. Results show how SPDY allows getting rid of the HTTP acceleration part deployed within the Performance Enhancing Proxy (PEP), thus reducing both the complexity (e.g., in terms of TCP connections) and the development costs experienced by the service provider.

Owing to the variety of traffic profiles that Machine to Machine and SCADA applications may generate, this work focuses on the applicability of a DVB-RCS2 terminal, configured with the SCADA system profile, when clusters of sensor nodes exchange data via satellite toward a central operational control station using TCP/IP connections. We propose a realistic architecture for integrating wireless sensor and satellite networks, covering technological issues from the access layer to the transport and session layers; in our scenario, uncorrelated sensor sources generate measurements' data, which are multiplexed by a satellite gateway before being encapsulated and delivered through TCP/IP flows. According to the traffic nature and the available access methods in the satellite terminal, the suitability of a random access method in place of a dedicated one is an open issue, when throughput and delivery delay are the performance metrics at transport layer. This work aims at investigating when the satellite random access methods based on successive interference cancellation are convenient in terms of access delay and employed resources, by guaranteeing a performance, in terms of throughput, comparable to that obtained by means of demand assignment multiple access systems.

This paper aims at highlighting the fundamental issues when the TCP and the Contention Resolution Diversity Slotted Aloha (CRDSA) protocols are coupled, in the case of greedy TCP connections (also called elephants) on a Digital Video Broadcasting- Return Channel via Satellite (DVB-RCS). CRDSA takes advantage of interference cancellation algorithms for collision/contention resolution, by achieving an actual increment in performance in terms of throughput. This improvement is obtained not only in the case of a multitude of users with a pretty low traffic load, but even at values of the global access network load in the range 50-70% - a threshold that was considered unreachable with the ancestor releases of slotted Aloha protocols.

application scenarios that have been selected in the previous deliverable TN 2.1 "WSN-Satellite Network Architecture and Scenarios". The methodologies that will be studied are briefly described. In the first part, the general assumptions regarding the quality of service (QoS) in Wireless Sensor Networks (WSNs), the technologies and the traffic profiles are given. In the next part, the TN is devoted to presentation of the principles of collaborative beamforming and of the link budget parameters, while afterwards the techniques for clustering (MADM and game theory) and data fusion, and the cooperative routing for satellite-controlled WSNs are presented. Every part contains also the corresponding analytical results and simulations as well as a discussion on them. Finally, the assumptions and the simulation setup for the efficient access and transport techniques among sensors and satellite are presented. In all the above-described scenarios the energy constraints are considered.

This document is aimed at highlighting the possible open issues for future R&D lines when satellite networks are applied in the field of wireless sensors networks, based on the findings summarized in TNs 2.2 and 2.3 and starting from the architectural assumptions in T.2.1. In particular, the attention is devoted to selected scenarios, where the applicability of satellite technologies requires a careful analysis of technological & performance issues that may rise when so different technologies, i.e., sensors and satellites, are joined together. Last point is finally dedicated to the dissemination activity resulted from this study, thus showing and motivating the research activity in this field.

The aim of this document is to summarize the main results achieved in the study "The role of satellites in future sensor networks" being part of the CoO-2 call of SatNEx III project (Task 2), commissioned by ESA in contract RFQ/3-12859/09/NL/CLP. This analysis primarily aimed to overview the current research activities performed in this field and then to investigate the potential applications that an integrated architecture constituted by sensor networks and satellite links may have in some satellite-based scenarios. Five scenarios have been investigated in terms of specific requirements and traffic characteristics; the traffic characteristics of the studied scenarios have allowed compressing the five original scenarios to three scenarios. All possible technologies (available at the writing time) usable in satellite and in sensor networks have been analyzed, together with techniques for data routing, clustering, data fusion, satellite access algorithms, data models for sensor network traffic. The performance evaluations of various aspects of the integrated system have been done according to well-defined evaluation parameters. Distributed collaborative beamforming has also been studied, and security aspects both in WSNs, in satellite networks, and in hybrid WSN-satellite combinations have been deeply addressed. A new algorithm for intrusion resilience in unattended WSNs has been studied and evaluated. This document concludes summarizing the challenging research aspects that could be further investigated. All the specific discussions and results are detailed in the relevant Technical Note (TN) cited in the text and that constitute the references of this report. In the mentioned TNs, the papers related to the single aspects are listed.

of satellites in future sensor networks" being part of the CoO-2 call of SatNEx III project (Task 2), commissioned by ESA in contract RFQ/3-12859/09/NL/CLP. The work primarily aimed at overviewing the current research activities performed in this field and then to investigate the potential applications that an integrated architecture constituted by sensor networks and satellite links may have in some satellite-based scenarios. Five scenarios have been investigated in terms of specific requirements and traffic characteristics; the traffic characteristics of the studied scenarios have allowed compressing the five original scenarios to three scenarios. All possible technologies (available at the writing time) usable in satellite and in sensor networks have been analyzed, together with techniques for data routing, clustering, data fusion, satellite access algorithms, data models for sensor network traffic. The performances of various aspects of the integrated system have been evaluated according to specific evaluation parameters. Distributed collaborative beamforming has also been studied, and security aspects both in WSNs, in satellite networks, and in hybrid WSN-satellite combinations have been deeply addressed. A new algorithm for intrusion resilience in unattended WSNs has been studied and evaluated. This document concludes summarizing the challenging research aspects that could be further investigated. All specific discussions and results are detailed in the Technical Notes (TN) listed as "Related documents". Each of these TNs contains hundreds of references to the literature.