Delay Tolerant Networks Networks Research Articles

Impact of Renewable Energy Resources on the Performance of DTN Networks in the Context of Hierarchical Routing Tree Topology (HRTT)

Delay-Tolerant Networks (DTN) are mobile networks specifically designed to operate in challenging wireless environments where connectivity is not guaranteed, and various issues such as frequent disconnections, long delivery delays, low delivery rates, and high error rates are common. One of the major problems of DTN networks is limited energy resources which impose strict constraints on the operational lifespan of DTN nodes. To solve these problems, we propose the adoption of a long-term strategy for energy management, based on the exploitation of renewable energies and the improvement of the HRTT topological architecture through the direct integration of renewable energy sources within DTN nodes. Indeed, DTN nodes powered by renewable energy resources, such as solar energy, have the potential to recharge themselves, extending their operational lifespan, increasing their storage and transmission capabilities, and reducing dependence on non-renewable energy resources. In this article, we assess the impact of limited energy resources and renewable energy resources like solar panels on the energy performance of DTN networks in the context of the Hierarchical Routing Tree Topology (HRTT), taking into account the average remaining energy as a performance metric. The evaluation of energy performance and the implementation of the HRTT topology are carried out using the ONE (Opportunistic Network Environment) simulator. According to the simulation results, the average remaining energy of nodes using renewable resources is significantly higher compared to the initial energy levels of nodes for all DTN protocols adopted by the nodes in the context of the HRTT topology. However, the average remaining energy of nodes using limited resources is lower compared to their initial energy levels for all DTN protocols adopted by the nodes in the context of the HRTT topology.

DTN Architecture With Resource-Aware Rate Adaptation for Multiple Bundle Transmission in InterPlanetary Networks

The world of telecommunications, from some years, is revitalizing an high interest to Deep Space Communication (DSC) and Delay Tolerant Network (DTN) architecture as enabling technologies to offer internet services for aerospace vehicles or orbital stations. The communications between the planets in the solar system is well known to present a series of problems that need to be faced. The fundamental challenge with InterPlanetary Communication (IPC) is the intermittent Line of Sight (LoS) caused by planets movement and the significant propagation time. A possible way to face with it is the use of a DTN approach where routers use a store-and-forward transmission in a hop-by-hop message exchange mechanism. Thanks to this approach, it is possible to face many issues related to the transport layer. The main contribution of this work concerns the proposal of a bundle management layer able to assign at the receiver the appropriate bundle rate on the basis of concurrent bundle transmissions, the output link capacity and buffer resources. The proposed strategy can be integrated with a routing algorithm for InterPlanetary Networks (IPNs) and DTN networks. In our case we consider the Earliest Arrival Optimal Delivery Ratio (EAODR) routing that applies a modified temporal graph to select the IPN nodes. Performance evaluation have been led out to show the benefits of our proposal on the single links and also on the routing scheme in terms of bundle delivery ratio and average bundle delivery time.

Delay Tolerant Network Protocols in a Railway Network

The paper is devoted to the analysis of the effectiveness of the DTN (delay tolerant network) system in a communication network on a railway line. Trains act as moving objects that are sending and receiving messages to/from an external network. Trains may also transmit telemetry collected during movement. The article presents data on the effectiveness of the DTN network with various protocols in terms of reducing the delay in the message and telemetry delivery and in increasing the total number of delivered messages in the railway scenario. An analysis of railway lines with various loads and different coverage of mobile networks was made. These models are based on real railway maps and train schedules. The effectiveness of DTN during migration to networks of a higher data rate (5G) and networks with satellite connection of trains is discussed.

Prioritized Content Determination and Dissemination Using Reinforcement Learning in DTNs

In a battlefield, several groups of soldiers are deployed with different missions by the command and control center (CC). To continue the missions appropriately and get a better understanding of the situation, the soldiers as well as the CC need to collect information of interest generated in different battle zones using Delay-tolerant Networks (DTN). It is a challenge to determine the topics of interest associated with the events and missions, and efficiently forward the associated content to the CC in this extreme situation. We design a scheme to forward contents generated by the nodes to the CC using Reinforcement Learning (RL) while maximizing the number of interesting data in the respective nodes buffer, and avoiding congestion. In this forwarding process, we focus on identifying the trending topics/keywords among changing missions and their related data at the node level, and the changes of interest of the nodes based on their mobility and connectivity patterns of nodes in DTN. Experiments are conducted using real datasets and ONE simulator to show the effectiveness of Reinforcement Learning (RL) on the prioritized content dissemination in DTN networks.

Effective Controlling Scheme to Mitigate Flood Attack in Delay Tolerant Network

Conventional routing protocols breaks down in opportunistic networks due to long delays, frequent disconnectivity and resource scarcity. Delay Tolerant Network (DTN) has been developed to cope with these mentioned features. In the absence of connected link between the sender and the receiver, in DTN mobile nodes replicate bundles and work cooperatively to improve the delivery probability. Malicious nodes may flood the network as possible by a huge number of unwanted bundles (messages) or bundle replicas which waste the limited resources. DOS (Denial of Service) attack especially Flooding attack attempt to compromise the availability service of the network. Traditional congestion control strategies are not suitable for DTN, so developing new mechanisms to detect and to control flooding attack is a major challenge in DTN network. In this paper, we presented a comprehensive overview of the existing solutions for dealing with flooding attack in delay tolerant network, and we proposed an effective controlling mechanism to mitigate this threat. The main goal of this mechanism is first to detect malicious nodes that flood the network by unwanted messages, and then to limit the damage caused by this attack. We also ran a large number of simulations with the ONE simulator to investigate how changing buffer capacity, message lifetime, message size, and message replicas affect DTN network performance metrics.

Efficient photo crowdsourcing with evolving POIs under delay-tolerant network environment

In a disaster or battlefield zone, rescue workers, soldiers, and other survivors (referred to as nodes) may need to survey damages and send images to the command and control center (the server) in a hop-by-hop fashion in the absence of any communication infrastructure. The server considers some area/landmark as the point of interest (POI) and distributes a request to the nodes to collect more information about them. Nodes take photos of POIs and share them with each other using the store and forward paradigm, also called Delay-tolerant Networks (DTNs), to send the photos to the server. Due to the highly intermittent contact characteristics of nodes in a DTN network and bandwidth and storage limitations, redundant photos need to be removed in this forwarding technique, whereas photos that cover different angles and views of the POIs need to be shared. Another challenge is that, over time, some server-listed POIs may not be of importance anymore, whereas some new POIs might be of more interest. In this work, we propose a scheme that is able to dynamically update the list of POIs based on the current photo metadata, with reduced consumption of the bandwidth, energy, and storage at DTN nodes by sending only important photos of POIs. In the performance evaluation, we show the scalability of our approach, and also show that it provides the same level of photo coverage but consumes much less energy and bandwidth than other related schemes.

A Diverse Band-Aware Dynamic Spectrum Access Network Architecture for Delay-Tolerant Smart City Applications

According to the Smart City Council, an adequate telecommunications infrastructure is vital for the success of businesses, industries as well as residents of Smart cities. However, currently available standard and cellular technologies, such as 3/4G, GSM (Global System for Mobile Communications) and LTE (Long-Term Evolution), are rapidly reaching their limit mainly due to increased traffic demand. Such limitations are only going to worsen in the next years, due to the advent of Internet of Things technologies that are expected to interconnect billions of devices to the Internet. In this paper, we propose a novel network architecture that supports several delay-tolerant (non-real-time) Smart city applications and services (e.g., gathering air pollution information), and therefore, a promising approach to address the burdening of increased traffic demand to Smart city’s legacy standard and cellular communication infrastructure. The proposed architecture is based on an innovative diverse band-aware Dynamic Spectrum Access ( d-DSA ) paradigm, that allows a certain wireless device to opportunistically access idle channels in multiple licensed/unlicensed spectrum bands. d-DSA radio devices are mounted on Smart city’s urban vehicles (e.g., taxis) that act as mobile routers to gather, carry, and forward various types of data traffic. This results in a time-varying and unpredictable delay-tolerant network (DTN) where each node can access whitespace channels and transmit in multiple spectrum bands. Given lack of research in efficient routing schemes for such d-DSA DTN networks, we propose a distributed and lightweight d-DSA aware Geographical Routing (dDSA-GR) protocol, that utilizes a weighted linear metric for selecting a suitable spectrum band, and classic georouting principle for choosing next hop node in the path route between any node pair in d-DSA DTNs. Results on realistic traces based on the map of Lexington, KY, USA, show that our dDSA-GR routing protocol outperforms baseline approaches in terms of network delay, message delivery ratio, and energy efficiency, under all considered scenarios.

DTN Routing Hierarchical Topology for the Internet of Things

Abstract New technologies have been expanding rapidly in recent years. These new technologies require new communication systems, such as delay tolerant networks (DTN). However, establishing communications is not enough. Networks must allow data to be exchanged and these data must be understood by the entities that receive them. Although a lot of DTN routing protocol has been proposed for DTN networks, but with the emergence of new technological applications such as drones, the Internet of Things, etc., the DTN routing protocol is still in use. It is desirable to develop a feasible, reliable and robust protocol for this new range of applications. In this work, we will present a DTN protocol for the Internet of Things (IoT) applications.

Delay Tolerant Network and the Algorithms of DTN Routing

Delay Tolerant Network (DTN) is a new type of network, which is different from traditional TCP / IP communication protocol network. It is suitable for extreme environment where end-to-end communication connection cannot be established stably. Firstly, the characteristics and structure of DTN are analyzed, then the characteristics of nodes in the network are also analyzed. Secondly, the DTN routing problem is explained. Next, the classification of DTN routing algorithms and some classical routing algorithms are introduced. Finally, some other problems of DTN are proposed. The stable operation of the TCP/IP protocol relies mainly on three underlying link features: (1) There is a stable and reliable end-to-end link between the source node and the destination node; (2) The maximum round trip time RTT (Round Trip Time) between any nodes is not long; (3) The probability of message loss during transmission is low [2]. DTN extends the application of IPN to terrestrial mobile communications, emergency communications, underwater communications and wildlife monitoring. DTN can make up for the shortcomings of existing communication networks and realize communication connections in extreme or special environments. In recent years, research on DTN has made great progress. Further in-depth research on the DTN network in the future will inevitably promote and promote network communication.

Simulation based Performance Comparison & Analysis regarding Static and Mobile Throwboxes impact on Network Performance in Delay Tolerant Networks (DTNs) using ONE Simulator

Delay Tolerant Network (DTN) is another category of network that lacks continuous network connectivity. Nodes are dependent on opportunistic contacts for message forwarding. Every node has a buffer space where messages are stored till the messages are forwarded to other nodes existing the network, till the message reach the destination node. Buffer space is a crucial resource in DTNs. When a buffer space becomes full, to accommodate new messages, older messages are dropped from buffer space. As nodes in DTN are subject to high data loss and intermittent connection problems. To overcome this issue, relay nodes, i.e. Throwboxes are introduced into the network. Throwboxes are tiny, inexpensive devices, acting as additional storage units for nodes to enhance the overall DTN based network performance. Throwboxes increases contact opportunities and improve over message delivery ratio. In this paper, we aim to analyze the performance of DTN network by introducing Static or Mobile throwboxes in the network in terms of Message Delivery Ratio, Latency and Contacts per hour. Extensive simulations are performed using ONE Simulator by considering both random and planned office-based scenarios. And it is observed via simulation-based results, that with introduction of Throwboxes in DTN, message delivery ratio is improvised at a whopping rate of 14%, latency is reduced by 10% and contacts per hour shows improvement by 25%.

Clique-Based Socially-Aware Intelligent Message Forwarding Scheme for Delay Tolerant Network

Delay tolerant network (DTN) is a challenged class of mobile ad hoc network that allows unbounded delay and intermittent contacts. In such a network the routing strategies involve storing a message and forward it to some future contact. In the past, most of the strategies defined were flooding based that eventually creates multiple duplicate copies of a message. This leads to the consumption of most of the network resources like energy, buffer space, processing power, etc. For this, we have extended our previous work based on artificial neural network based forwarding using trust value, which has potential to diminish these issues. Using trust as a modelling factor, we propose a trusted DTN clique which is socially aware and intelligently forwards in DTN. The work is examined using extensive simulation on real-world external traces. Also, the work is compared with existing routing protocols namely Prophet, SprayAndWait, and EpidemicOracle. The performance metric chosen for the proposed algorithm are messages aborted, messages relayed and messages dropped. Experimental results show that the proposed algorithm limits the number of message copies relayed in the DTN network and further provides a light weight intrinsic security to the DTN nodes.

Stochastic analysis of DTN routing protocols in delay tolerant network routing hierarchical topology

We propose in this work a topology adapted to the routing in the delay tolerant networks (DTN). This topology plays a very important role in the design and the implementation of routing protocols in this type of networks devoid of any infrastructure and any centralised administration with an intermittent connectivity. Indeed, we develop a DTN routing hierarchical topology (DRHT) which incorporates three fundamental concepts: ferries messages, ferries routes and clusters. The intra-cluster routing is managed by the cluster head, while the inter-cluster routing is managed by the ferries messages. This approach allows us to improve the performances of DTN networks. In addition, we present a modelling and an analysis of the process of the bundles distribution in a delay tolerant network through a Markov process of birth and death in continuous time; our modelling takes into account the characteristics of the DTN network. The simulations results have shown that our solution DRHT proves to be more effective and adequate in the context of the DTN networks compared to other existing approaches.

Identity‐based access control for pro‐active message's DTN

AbstractPro‐active message's delay tolerant networks (DTNs) are based on the usage of mobile code to obtain messages that contain their own routing code. This architecture allows applications to use the same network in different ways. The keystone of this type of heterogeneous network is a collection of contextual and application‐related information that it is stored in every node and accessed by the messages' routing code. Access to that information must be protected in order to make the whole architecture feasible; the operation of the network has to be secure, and attacks of information poisoning have to be avoided. We propose an identity‐based access control system for pro‐active message's DTN based on tools that are available in DTN networks, like symmetric key encryption and hashes. Our system grants confidentiality and integrity to the contextual information and solves the question of messages needing to use distributed information stored in nodes to route properly. The proof of concept of identity‐based access control in a certain kind of application demonstrates the feasibility of the proposal. The comparison between our proposal and other access control systems shows that identity‐based access control is the only system that fits well with the special characteristics of pro‐active message's DTN. Copyright © 2016 John Wiley & Sons, Ltd.

An optimization model for fragmentation-based routing in delay tolerant networks

The explosive growth of mobile data traffic has raised big penetration to cellular network. Fortunately, offloading part of traffic through Delay Tolerant Network (DTN) would be a promising option to relieve load pressure. However, the existing routing strategies designed for DTNs are inappropriate in offloading scenario, where i) large data item would take on the dominance of mobile traffic, ii) centralized control can be exploited with merge between DTN and cellular network. To improve the routing performance of large data transmission, we propose a novel optimization model by creating two-tier solution space based on fragmentation, maximizing the probability that the requested data item is successfully delivered before expiration, taking limited buffer space as constraint metric. Moreover, a specific routing scheme is instantiated from our model, which is supported by uniform fragmentation and fine-grained path selection. Extensive trace-driven simulations show that our scheme is more appropriate for offloading case with outstanding performance in terms of replication overhead and acceptable routing capability.

Improving Robustness in DTN Networks that Carries Large Medical Files in Amazonia

This paper presents a proposal for improving robustness and reliability in Delay Tolerant Networks (DTN), used to transmit large data files for healthcare applications. The scenario is the Marajo archipelago in the Brazilian Amazon, where communication infrastructure is almost non-existent and there is a special need for medical services. The use of Fountain codes, network coding and proximity layering to messages acknowledgments were investigated. Four Store-Carry-Forward protocols were analyzed by simulation and results show that the Spray and Wait protocol is the better option for the scenario.

Column Generation Algorithm-Based DTN Routing Strategy in Complex Data Transmission Scenario

An ideal routing strategy shall be able to help the delay tolerant network (DTN) achieve an optimal transmission performance under the premise of lower energy consumption. However, due to the diverse of the application scenarios, it is hard to use one or more types of routing strategies as a universal optimum solution. There is a need to establish a routing strategy model of the corresponding DTN network for different application scenarios, analyze and evaluate the strategy model in combination of the knowledge of the operational research and statistics. For a complex data transmission DTN network scenario, with the introducing of a line programming method, the big-data and multi-node network transmission problem can be abstracted to a large-scale line programming problem. In this paper, the feasibility of solving the large-scale line programming problem by the column generation algorithm has been analyzed, and a column generation algorithm-based DTN routing strategy under the complex data transmission scenario has been designed. This routing strategy can realize the quantization of the routing strategy performance by the column generation algorithm. Also, by the simulation experiments, the performance of complex data transmission DTN routing strategy under different factors has been analyzed, and the performance of the column generation algorithm-based DTN routing strategy has been compared with the performance of the traditional jet waiting routing strategy.

Endeavouring to be in the good books. Awarding DTN network use for acknowledging the reception of bundles

This paper describes an incentive scheme for promoting the cooperation, and, therefore, avoiding selfish behaviours, in Delay Tolerant Networks (DTN) by rewarding participant nodes with cryptographic keys that will be required for sending bundles. DTN are normally sparse, and there are few opportunistic contacts, so forwarding of other’s bundles can be left out. Moreover, it is difficult to determine the responsible nodes in case of bundle loss. The mechanism proposed in this paper contributes to both problems at the same time. On one hand, cryptographic receipts are generated using time-limited Identity Based Cryptography (IBC) keys to keep track of bundle transmissions. On the other hand, these receipts are used to reward altruistic behaviour by providing newer IBC keys. Finally, these nodes need these IBC keys to send their own bundles. When all nodes behave in a cooperative way, this incentive scheme works as a virtuous circle and achieves a Nash equilibrium, improving very much the network performance in terms of latency. The scheme is not difficult to implement, and it can use an already existing IBC infrastructure used for other purposes in a DTN.

Performance of Efficient Routing Protocol in Delay Tolerant Network: A Comparative Survey

Nowadays, the research and application about delay-tolerant network (DTN) have become more and more popular. A communications network that is capable of storing packets temporarily in intermediate nodes, until the time an end-to-end route is reestablished or regenerated is known as a delay tolerant network/s, in short, DTN.Routing of the packets in DTN is based on store-carry-and forward paradigm. When a node receives a message but no availability of paths towards destination node, the message should be buffered in the current node and wait for opportunities to encounter other nodes. This paper aims to detail basic & general aspects specific to information needs in DTN routing and present classification chart. We discuss some detail of routing issues and classifications of routing protocols. Routing is one of the major issues affecting the overall performance of DTN networks in terms of resource consumption, data delivery. Over the past few years a number of routing protocols have been proposed for DTN networks. In this paper mainly three DTN routing protocols Epidemic, PROPHET and Spray and Wait Routing protocols are discussed.

Topology Control for Time-Evolving and Predictable Delay-Tolerant Networks

In delay tolerant networks (DTNs), the lack of continuous connectivity, network partitioning, and long delays make design of network protocols very challenging. Previous DTN research mainly focuses on routing and information propagation. However, with a large number of wireless devices' participation, it becomes crucial regarding how to maintain efficient and dynamic topology of the DTN. In this paper, we study the topology control problem in a predictable DTN, where the time-evolving network topology is known a priori or can be predicted. We first model such time-evolving network as a directed space-time graph that includes both spacial and temporal information. The aim of topology control is to build a sparse structure from the original space-time graph such that 1) the network is still connected over time and supports DTN routing between any two nodes; 2) the total cost of the structure is minimized. We prove that this problem is NP-hard, and propose two greedy-based methods that can significantly reduce the total cost of topology while maintaining the connectivity over time. We also introduce another version of the topology control problem by requiring that the least cost path for any two nodes in this constructed structure is still cost-efficient compared with the one in the original graph. Two greedy-based methods are provided for such a problem. Simulations have been conducted on both random DTN networks and real-world DTN tracing data. Results demonstrate the efficiency of the proposed methods.

Spray and Dynamic: Advanced Routing in Delay Tolerant Networks

This paper addresses the problem of routing in delay tolerant networks (DTNs). Delay tolerant networks are wireless networks where disconnections occur frequently due to mobility of nodes, failures of energy, the low density of nodes, or when the network extends over long distances. In these cases, traditional routing protocols that have been developed for mobile ad hoc networks prove to be ineffective to the extent of transmitting messages between nodes. To resolve this problem and improve the performance of routing in delay tolerant networks we propose a new routing protocol called Spray and Dynamic; this approach represents an improvement of the spray and wait protocol by combining it with the two protocols: MaxProp and the model of “transfer by delegation” (Custody Transfer). To implement our approach Spray and Dynamic, we have developed a DTN simulator according to DTN network architecture.