Dtn and non-dtn routing protocols for inter-cubesat communications: A comprehensive survey

CubeSats, which are limited by size and mass, have limited functionality. These miniaturised satellites suffer from a low power budget, short radio range, low transmission speeds, and limited data storage capacity. Regardless of these limitations, CubeSats have been deployed to carry out many research missions, such as gravity mapping and the tracking of forest fires. One method of increasing their functionality and reducing their limitations is to form CubeSat networks, or swarms, where many CubeSats work together to carry out a mission. Nevertheless, the network might have intermittent connectivity and, accordingly, data communication becomes challenging in such a disjointed network where there is no contemporaneous path between source and destination due to satellites’ mobility pattern and given the limitations of range. In this survey, various inter-satellite routing protocols that are Delay Tolerant (DTN) and Non Delay Tolerant (Non-DTN) are considered. DTN routing protocols are considered for the scenarios where the network is disjointed with no contemporaneous path between a source and a destination. We qualitatively compare all of the above routing protocols to highlight the positive and negative points under different network constraints. We conclude that the performance of routing protocols used in aerospace communications is highly dependent on the evolving topology of the network over time. Additionally, the Non-DTN routing protocols will work efficiently if the network is dense enough to establish reliable links between CubeSats. Emphasis is also given to network capacity in terms of how buffer, energy, bandwidth, and contact duration influence the performance of DTN routing protocols, where, for example, flooding-based DTN protocols can provide superior performance in terms of maximizing delivery ratio and minimizing a delivery delay. However, such protocols are not suitable for CubeSat networks, as they harvest the limited resources of these tiny satellites and they are contrasted with forwarding-based DTN routing protocols, which are resource-friendly and produce minimum overheads on the cost of degraded delivery probability. From the literature, we found that quota-based DTN routing protocols can provide the necessary balance between delivery delay and overhead costs in many CubeSat missions

Power - Aware Resource Management for Sensor - Actor Networks

Mobile sensor actuator networks have been applied in a wide range of real-world applications. Because nodes in sensor networks are powered by batteries, two major problems arise. First, the nodes do not last long because of limited power supply. Second, only limited amount of data can be transferred if proper mobility strategies are not designed. In this research, we propose the concept of pipelining of mobile nodes to asynchronously transfer and relay data in the network. Through a number of simulations we examine the design tradeoff of performance and energy cost. Performance evaluation through simulations has been conducted by number of mobile nodes. The proposed pipelining strategy yields three major benefits. First, as the number of mobile nodes increases, rate of data transfer increases. Second, energy required per data transfer decreases. Finally, life time of the network increases compared to traditional non-pipelining mobility strategy.Computer Science Departmen

Topology design for time-varying networks

Traditional wireless networks seek to support end-to-end communication through either a single-hop wireless link to infrastructure or multi-hop wireless path to some destination. However, in some wireless networks (such as delay tolerant networks, or mobile social networks), due to sparse node distribution, node mobility, and time-varying network topology, end-to-end paths between the source and destination are not always available. In such networks, the lack of continuous connectivity, network partitioning, and long delays make design of network protocols very challenging. Previous DTN or time-varying network research mainly focuses on routing and information propagation. However, with large number of wireless devices' participation, and a lot of network functionality depends on the topology, how to maintain efficient and dynamic topology of a time-varying network becomes crucial. In this dissertation, I model a time-evolving network as a directed time-space graph which includes both spacial and temporal information of the network, then I study various topology control problems with such time-space graphs. First, I study the basic topology design problem where the links of the network are reliable. It aims to build a sparse structure from the original time-space graph such that (1) the network is still connected over time and/or supports efficient routing between any two nodes; (2) the total cost of the structure is minimized. I first prove that this problem is NP-hard, and then propose several greedy-based methods as solutions. Second, I further study a cost-efficient topology design problem, which not only requires the above two objective, but also guarantees that the spanning ratio of the topology is bounded by a given threshold. This problem is also NP-hard, and I give several greedy algorithms to solve it. Last, I consider a new topology design problem by relaxing the assumption of reliable links. Notice that in wireless networks the topologies are not quit predictable and the links are often unreliable. In this new model, each link has a probability to reflect its reliability. The new reliable topology design problem aims to build a sparse structure from the original space-time graph such that (1) for any pair of devices, there is a space-time path connecting them with the reliability larger than a required threshold; (2) the total cost of the structure is minimized. Several heuristics are proposed, which can significantly reduce the total cost of the topology while maintain the connectivity or reliability over time. Extensive simulations on both random networks and real-life tracing data have been conducted, and results demonstrate the efficiency of the proposed methods

A shared opportunistic infrastructure for long-lived wireless sensor networks

In this paper, a Shared Opportunistic Infrastructure (SOI) is proposed to reduce total cost of ownership for long-lived wireless sensor networks through exploiting human mobility. More specifically, various sensor nodes are opportunistically connected with their corresponding servers through smart phones carried by people in their daily life. In this paper, we will introduce the motivations, present the architecture, discuss the feasibility, and identify several research opportunities of SOI

Methodologies for the analysis of value from delay-tolerant inter-satellite networking

In a world that is becoming increasingly connected, both in the sense of people and devices, it is of no surprise that users of the data enabled by satellites are exploring the potential brought about from a more connected Earth orbit environment. Lower data latency, higher revisit rates and higher volumes of information are the order of the day, and inter-connectivity is one of the ways in which this could be achieved. Within this dissertation, three main topics are investigated and built upon. First, the process of routing data through intermittently connected delay-tolerant networks is examined and a new routing protocol introduced, called Spae. The consideration of downstream resource limitations forms the heart of this novel approach which is shown to provide improvements in data routing that closely match that of a theoretically optimal scheme. Next, the value of inter-satellite networking is derived in such a way that removes the difficult task of costing the enabling inter-satellite link technology. Instead, value is defined as the price one should be willing to pay for the technology while retaining a mission value greater than its non-networking counterpart. This is achieved through the use of multi-attribute utility theory, trade-space analysis and system modelling, and demonstrated in two case studies. Finally, the effects of uncertainty in the form of sub-system failure are considered. Inter-satellite networking is shown to increase a system's resilience to failure through introduction of additional, partially failed states, made possible by data relay. The lifetime value of a system is then captured using a semi-analytical approach exploiting Markov chains, validated with a numerical Monte Carlo simulation approach. It is evident that while inter-satellite networking may offer more value in general, it does not necessarily result in a decrease in the loss of utility over the lifetime.In a world that is becoming increasingly connected, both in the sense of people and devices, it is of no surprise that users of the data enabled by satellites are exploring the potential brought about from a more connected Earth orbit environment. Lower data latency, higher revisit rates and higher volumes of information are the order of the day, and inter-connectivity is one of the ways in which this could be achieved. Within this dissertation, three main topics are investigated and built upon. First, the process of routing data through intermittently connected delay-tolerant networks is examined and a new routing protocol introduced, called Spae. The consideration of downstream resource limitations forms the heart of this novel approach which is shown to provide improvements in data routing that closely match that of a theoretically optimal scheme. Next, the value of inter-satellite networking is derived in such a way that removes the difficult task of costing the enabling inter-satellite link technology. Instead, value is defined as the price one should be willing to pay for the technology while retaining a mission value greater than its non-networking counterpart. This is achieved through the use of multi-attribute utility theory, trade-space analysis and system modelling, and demonstrated in two case studies. Finally, the effects of uncertainty in the form of sub-system failure are considered. Inter-satellite networking is shown to increase a system's resilience to failure through introduction of additional, partially failed states, made possible by data relay. The lifetime value of a system is then captured using a semi-analytical approach exploiting Markov chains, validated with a numerical Monte Carlo simulation approach. It is evident that while inter-satellite networking may offer more value in general, it does not necessarily result in a decrease in the loss of utility over the lifetime

On exploiting priority relation graph for reliable multi-path communication in mobile social networks

© 2018 Elsevier Inc. A mobile social network (MSN) consists of certain amount of mobile users with social characteristics, and it provides data delivery concerning social relationships between mobile users. In MSN, ordinary people contact each other more frequently if they have more social features in common. In this paper, we apply a new topology structure–priority relation graph (PRG) to evaluate the data delivery routing in MSN on the system-level. By using the natural order of nodes’ representation, the diameter, the regular degree and the multi-path technology, we determine the priority relation graph-based social feature routing (PRG-SFR) algorithm to find disjointed multi-paths in MSN. Here, the multi-path technology can be exploited for ensuring that, between each pair of sender and receiver, the important information can be delivered through a highly reliable path. Then we calculate the tolerant ability of ‘faults’ and estimate the availability of MSN on the theoretical level. Finally, we analyze the efficiency of PRG-SFR algorithm from the numerical standpoint in terms of fault tolerance, forwarding number, transmission time and delivery rate. Moreover, we make comparisons between PRG-SFR algorithm and certain state-of-the-art technologies

Edge-Computing-Based Channel Allocation for Deadline-Driven IoT Networks

Multichannel communication is an important means to improve the reliability of low-power Internet-of-Things (IoT) networks. Typically, data transmissions in IoT networks are often required to be delivered before a given deadline, making deadline-driven channel allocation an essential task. The existing works on time-division multiple access often fail to establish channel schedules to meet the deadline requirement, as they often assume that transmissions can be successful within one transmission slot. Besides, the allocation and link estimation incur considerable overhead for the IoT nodes. In this article, we propose an edge-based channel allocation (ECA) for unreliable IoT networks. In ECA, we explicitly consider the impact of allocation sequences and employ a recurrent-neural-network-based channel estimation scheme. We utilize link quality and retransmission opportunities to maximize the packet delivery ratio before deadline. The allocation algorithms are executed on edge servers such that: 1) the channel allocation can be updated more frequently to deal with the wireless dynamics; 2) the allocation results can be obtained in real time; and 3) channel estimation can be more accurate. Extensive evaluation results show that ECA can significantly improve the reliability of deadline-driven IoT networks

A critical review of the routing protocols in opportunistic networks.

The goal of Opportunistic Networks (OppNets) is to enable message transmission in an infrastructure less environment where a reliable end-to-end connection between the hosts in not possible at all times. The role of OppNets is very crucial in today’s communication as it is still not possible to build a communication infrastructure in some geographical areas including mountains, oceans and other remote areas. Nodes participating in the message forwarding process in OppNets experience frequent disconnections. The employment of an appropriate routing protocol to achieve successful message delivery is one of the desirable requirements of OppNets. Routing challenges are very complex and evident in OppNets due to the dynamic nature and the topology of the intermittent networks. This adds more complexity in the choice of the suitable protocol to be employed in opportunistic scenarios, to enable message forwarding. With this in mind, the aim of this paper is to analyze a number of algorithms under each class of routing techniques that support message forwarding in OppNets and to compare those studied algorithms in terms of their performances, forwarding techniques, outcomes and success rates. An important outcome of this paper is the identifying of the optimum routing protocol under each class of routing

Opportunistic data collection through delegation

We consider a collection system where collectors move around gathering information generated by data producers. In such a system, data may remain uncollected when the number of collectors is insufficient to cover the whole population of producers. Motivated by the observation that node encounters are sufficient to build a connected relationship graph, we propose to take advantage of the inherent interactions among nodes and transform some producers into delegates. With such an approach, collectors only need to meet delegates that, in turn, are responsible for gathering data from a subset of standard producers. We achieve this goal through two contributions. First, we investigate several delegation strategies based on the relative importance of nodes in their social interactions (i.e., the node centrality). Second, by considering a prediction strategy that estimates the likelihood of two nodes meeting each other, we investigate how the delegation strategies perform on predicted traces. We evaluate the delegation strategies both in terms of coverage and size of the delegation existing real mobility data sets. We observe that delegation strategies that rely on localized information perform as well as the ones that consider a complete view of the topology.Nous considérons un système de collecte où les collectionneurs se déplacent et collectent les informations générées par les producteurs de données. Dans un tel système, les données peuvent ne pas être collectées lorsque le nombre de collectionneurs est insuffisant pour couvrir l'ensemble de la population des producteurs. Motivé par le fait que les rencontres de nœuds sont suffisants pour construire un graphe connecté, nous proposons de profiter des interactions inhérentes entre les nœuds et transformer certains producteurs en délégués. Avec une telle approche, les collectionneurs ont seulement besoin de rencontrer les délégués que, à leur tour, sont responsables de la collecte de données d'un sous-ensemble des producteurs. Nous atteignons cet objectif grâce à deux contributions. Tout d'abord, nous étudions plusieurs stratégies de délégation basée sur l'importance relative des nœuds dans leurs interactions sociales (par exemple, la centralité du nœud). Deuxièmement, en considérant une stratégie de prédiction qui donne les estimations de la probabilité d'une rencontre de deux nœuds, nous étudions les stratégies de délégation avec les traces prédit. Nous évaluons les stratégies de délégation à la fois en termes de couverture et de la taille du groupe de délégation en utilisant des traces de mobilité réelles. Nous n'observons que les stratégies de délégation qui se basent sur des informations localisées fournis aussi des bons résultats comparés aux résultats considérant une vue complète de la topologie

Unterbrechungstolerante Fahrzeugkommunikation im öffentlichen Personennahverkehr

Communication systems play an important role in the efficient operation of public transport networks. Recently, traditional voice-centric real-time communication is complemented and often replaced by data-centric asynchronous machine-to-machine communication. Disruption tolerant networking in combination with license-exempt high bandwidth technologies have the potential to reduce infrastructure investments and operating costs for such applications, because a continuous end-to-end connectivity is no longer required. In this thesis the feasibility of such a system is investigated and confirmed. First, realistic use-cases are introduced and the requirements to the communication system are analyzed. Then the channel characteristics of several WLAN-based technologies are experimentally evaluated in real public transport scenarios. Since the results are promising, the next step is gaining a deeper understanding of the special mobility properties in public transport networks. Therefore, we analyze existing traces as well as our own newly acquired trace. Our trace features additional operator meta-data that is not available for existing traces, and we report on unexpected properties that have not been quantified before. Then the trace is combined with the experimentally obtained channel parameters in order to analyze the characteristics of inter-vehicle contacts. We present the statistical distribution of situation-specific contact events and the impact of radio range on contact capacity. Then results of all steps above are used to propose a routing scheme that is optimized for public transport networks. In the final simulation-based evaluation we show that this router outperforms previously proposed algorithms.Kommunikationssysteme leisten einen wichtigen Beitrag zum effizienten Betrieb des öffentlichen Personennahverkehrs. Seit einigen Jahren wird dabei der Sprechfunk zunehmend durch asynchronen M2M-Datenfunk ergänzt und in vielen Anwendungsgebieten sogar vollständig ersetzt. Die Kombination aus unterbrechungstoleranten Netzwerken und lizenzfreien Drahtlostechnologien birgt ein erhebliches Potential zur Reduzierung von Infrastrukturinvestitionen und Betriebskosten, da für diese Anwendungen eine dauerhafte Ende-zu-Ende Verbindung nicht mehr erforderlich ist. In dieser Arbeit wird die Machbarkeit eines solchen Systems untersucht und belegt. Zunächst werden dazu Anwendungsfälle vorgestellt und deren Anforderungen an das Kommunikationssystem analysiert. Dann werden die Kanalcharakteristika mehrerer WLAN-Technologien im realen ÖPNV-Umfeld experimentell ermittelt und bewertet. Auf Grundlage der erfolgversprechenden Ergebnisse werden im nächsten Schritt die besonderen Mobilitätseigenschaften von ÖPNV-Netzen untersucht. Zu diesen Zweck analysieren wir existierende und eigene, neu aufgezeichnete Bewegungsdaten von ÖPNV-Fahrzeugen. Unsere Daten enthalten dabei zusätzliche Metadaten der Verkehrsbetriebe, die zuvor nicht verfügbar waren, so dass wir unerwartete Effekte beschreiben und erstmals quantifizieren können. Anschließend werden die Bewegungsdaten mit den zuvor experimentell erfassten Kanaleigenschaften kombiniert, um so die Kommunikationskontakte zwischen den Fahrzeugen genauer zu betrachten. Wir stellen die statistische Verteilung der situationsabhängigen Kontaktereignisse vor, sowie den Einfluss der Funkreichweite auf die Kontaktkapazität. Dann werden die Ergebnisse aller vorhergehenden Schritte verwendet, um ein neues, optimiertes Routingverfahren für ÖPNV-Netze vorzuschlagen. In der simulationsbasierten Evaluation belegen wir, dass dieser Router die Leistung bisher bekannter Verfahren übertrifft