Performance Of Delay Tolerant Networks Research Articles

A context-aware improved POR protocol for Delay Tolerant networks

ABSTRACT The intermittent network connectivity and unawareness of global network knowledge are remarkable challenges when designing efficient Position-based Opportunistic Routing (POR) for Delay Tolerant Networks (DTNs). The best progress set selection of POR effectively handles the intermittent connectivity issue and improves the reliable performance of DTNs. Hence, the optimal progress set selection and catching capacity decide the routing reliability of DTN-POR. This paper proposes a context-aware DTN-POR protocol STAP to ensure reliable DTN routing with minimum overhead STAP design is divided into three folds: application diversity and network failures, context-aware best progress set selection, and enhanced caching management. The application diversity and network failure switch the nodes in harsh environments to DTN mode for transmitting the data packets successfully to the destination. Selecting context-aware relay nodes ensures highly successful data transmissions in the absence of end-to-end connectivity. The probability estimation maximizes the data reachability by considering unique node and application-level context attributes in the best progressive set. Finally, the enhanced catching management strategy limits the number of data copies with effective catch invalidation, resulting in minimum overhead. The proposed STAP accomplishes better results in different scenarios and improves the packet delivery ratio with a minimum duplication rate.

Priority-based Approach to Mitigate Selfish Misbehaviour in Delay Tolerant Network

Delay tolerant networks (DTNs) is a solution to challenged networks which suffer from intermittent connectivity or high delay, thereby offering delay-tolerant support. DTN focuses on minimising delay and maximising forwarding and delivery ratio of data packets. DTN follows the store-carry-forward mechanism where a message is sent to the closest node using a store-carry-forward mechanism. Due to limited resources, poor connectivity and no centralised control, DTN is vulnerable to various attacks. These circumstances lead to the misbehaviour of network nodes and degrade the performance of the system. In this paper, first, we present a comprehensive review of the performance and security of DTN to identify 16 critical parameters allied to similar opportunistic networks. In the second phase of the article, the problem of node misbehaviour in DTN is analysed, and a novel priority-based approach to mitigate selfish misbehaviour is proposed. The acclaimed approach is validated using ONE simulator and exhibits improved results.

Non-dominated Sorting Genetic Algorithm-II for Throwbox Deployment in Delay Tolerant Networks

Delay-tolerant networks (DTNs) are basically opportunistic networks and uses store-carry-and-forward switching for message forwarding. Performance of DTNs can be improved by placing stationary nodes, called throwboxes which increases the contact opportunities among nodes. Throwbox is viewed as relaying node and the message delivery is enhanced by spreading as many messages as possible. Increasing the contact opportunities in throwbox based DTN model depends on the deployment of throwboxes in suitable places. The objective of this paper is to identify optimal deployment locations of the throwboxes with a pre-specified transmission range, and to maximize the coverage of all the throwboxes in order to increase average delivery and to reduce the average delay among all the nodes in the network. We use Non-Dominated Sorting Genetic Algorithm–II for optimizing the deployment of throwboxes in DTN. The simulation results are analyzed for better strategy in deploying throwboxes and to improve the performance of throwbox-augmented DTNs.

Performance Evaluation of Epidemic Content Retrieval in DTNs With Restricted Mobility

In some applicable scenarios, such as community patrolling, mobile nodes are restricted to move only in their own communities. Exploiting the meetings of the nodes within the same community and the nodes within the neighboring communities, a delay tolerant network (DTN) can provide communication between any two nodes. In this paper, two analytical models based on stochastic reward nets (SRNs) are proposed to evaluate the performance of the epidemic content retrieval in such multi-community DTNs. Performance measures computed by the proposed models are the average retrieval delay and the average number of transmissions. The monolithic SRN model proposed in the first step is not scalable, in terms of the number of communities and nodes, due to the state space explosion in the underlying Markov chain. In order to solve the scalability problem of the monolithic model, an approximate model based on the folding technique is presented which allows us to evaluate the performance of large-scale DTNs. In order to cross-validate the results obtained from the proposed models, we extend the ONE simulator to support our network model. The analytic-numeric results indicate that both models have good accuracy, and the folded model reduces the state space highly, achieving good scalability without any significant loss of accuracy.

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%.

Improving DTNs Performance by Reduction of Bundles Redundancy using Clustering Algorithm

This article presents complex clustering algorithm for Delay Tolerant Networks (DTNs) including neighborhood discovery, cluster creation, and data distribution within cluster. The general idea is to reduce the amount of messages being sent and of buffer utilization, by taking advantage of the nodes tendency to create groups and to share similar mobility patterns among each other. The main purpose of the algorithm is to improve the network performance without major changes in communication schemes between nodes. Almost no extra message type is added. Most extra features are available thanks to adding small extra fields into transmitted packages. Neighborhood discovery is being realized passively by listening to other nodes messages. The proposed algorithms allow to reduce both the bandwidth occupation, as well as the problems related to the media access. Furthermore, it can increase message delivery probability thanks to intelligent package distribution inside created cluster. Simulations were carried out to evaluate the effectiveness of the proposed solution in terms of package delivery probability, mean buffer occupancy and mean hop number to delivery the message. Results of simulation show that this solution is not necessary or recommended for small-scale networks with few nodes using clustering algorithms. However, with increasing number of nodes and messages, the performance of non-clustered DTNs drops significantly while clustered network works efficiently.

Using Ferry Access Points to Improve the Performance of Message Ferrying in Delay-Tolerant Networks

Delay-Tolerant Networks (DTNs) are sparse, wireless networks where disconnections are common due to host mobility and low node density. The Message Ferrying (MF) scheme is a mobilityassisted paradigm to improve connectivity in DTN-like networks. A ferry or message ferry is a special node in the network which has a per-determined route in the deployed area and relays messages between mobile hosts (MHs) which are intermittently connected. Increased contact opportunities among mobile hosts and the ferry improve the performance of the network, both in terms of message delivery ratio and average end-end delay. However, due to the inherent mobility of mobile hosts and pre-determined periodicity of the message ferry, mobile hosts may often ’miss’ contact opportunities with a ferry. In this paper, we propose the combination of stationary ferry access points (FAPs) with MF routing to increase contact opportunities between mobile hosts and the MF and consequently improve the performance of the DTN. We also propose several placement models for deploying FAPs on MF routes. We evaluate the performance of the FAP placement models through comprehensive simulation. Our findings show that FAPs do improve the performance of MF-assisted DTNs and symmetric placement of FAPs outperforms other placement strategies. Keywords—Service infrastructure, delay-tolerant network, message ferry routing, placement models.

Evaluating the Impact of Network Conditions on Routing Performance in Delay Tolerant Networks

The impact of network conditions on routing performance in DTN network has been investigated by means of the simulation experiment. The results show that appropriate number of duplicate messages is a simple and effective policy for store-carry-forward routing design. It performs well in most of the network conditions. It performs well in most of the network conditions in terms of delay, packet delivery ratio and overhead.

Survey and Comparison of Operating Concept for Routing Protocols in DTN

Delay Tolerant Network (DTN) are promising techniques to enable data transmission in challenging scenarios where sophisticated infrastructure is not available and the end-to-end path does not exist at the moment of data transmission. These networks are characterized by a long delay, intermittent connectivity and high error rates. Furthermore, the dynamic topology of the network may change randomly. Therefore, routing is one of the most crucial issues that affect the performance of DTN in terms of data delivery, latency and using resources if node mobility is considered. The routing design in DTN raises many challenges to the networks. Therefore, the problem of how to route a packet from one node to another in DTN is of the essence. This paper puts forward a rigorous survey of various routing protocols as well as performs a comparison of diverse routing strategies regarding significant issues in DTN.

Delay tolerant network: routing issues and performance

Delay tolerant networks (DTNs) are deployed in long distance data communications where delay is permissible like in interplanetary networks (IPNs). For the transfer of messages in a DTN, various routing schemes have been proposed but there has not been an umpteen amount of work related to their comparisons. Therefore, a study of the routing techniques, issues in DTN connectivity and performance analysis of routing algorithms in DTN have been showcased in the current work. This analysis would help the researchers in identifying the most efficient routing scheme amongst well known routing algorithms.

Delay tolerant network: routing issues and performance

Delay tolerant networks (DTNs) are deployed in long distance data communications where delay is permissible like in interplanetary networks (IPNs). For the transfer of messages in a DTN, various routing schemes have been proposed but there has not been an umpteen amount of work related to their comparisons. Therefore, a study of the routing techniques, issues in DTN connectivity and performance analysis of routing algorithms in DTN have been showcased in the current work. This analysis would help the researchers in identifying the most efficient routing scheme amongst well known routing algorithms.

TR-SDTN: Trust Based Efficient and Scalable Routing in Hostile Social DTNs

A delay tolerant network (DTN) presents a new communication model, which uses a store-carry-forward approach to deliver messages due to the nature of the network. With the development of the mobile internet, the research on DTNs becomes a hot topic. One critical issue in the DTNs with social characteristics is that there could exist selfish and malicious nodes which block important data and as a result intentionally disturb the communication. Although there are many research works which address the issue and adopt various trust models to encourage nodes to forward information, most of them have not considered the social characteristics of the mobile nodes and they have not handled the selfish behaviors and attacks in a systematic way. In view of these defects, we propose a novel solution to address the selfish and security issues in social DTNs. Based on nodes’ social characteristics, a dynamic trust model is proposed to prevent bad-mouthing and ballot stuffing attacks and the Shannon entropy function is introduced to avoid blackhole and greyhole attacks. The simulation results show that our proposed scheme can significantly improve the performance of social DTNs. And the simulation is proved to be consistent with the results from theoretical analysis.

DFCT: A New Data Forwarding Algorithm Based on Cumulative Performance and Transient Performance in DTNs

Delay Tolerant Networks (DTNs) are lack of end-to-end links. In order to overcome the frequent link interrupt, DTNs are often the store-carry-forwarding mechanism. Most routing forwarding algorithm only consider cumulative contact situation between network node and destination node, but in DTNs the frequent change of network topology can cause a lot of transient contact situation between network node and destination node. In order to make the fullest use of these transient contact situations, this paper proposes a new data forwarding algorithm based on cumulative performance and transient performance. It combines the cumulative performance and transient conditions between network node and destination node. We can choose a better relay node, so as to more efiectively improve the network performance. Then we use a realistic trace flle for simulation experiment, and compared with the two classic routing algorithms of Epidemic and Label. The experimental results show that the proposed algorithm can obviously reduce the network overhead compared with Epidemic algorithm and Label algorithm, and is close to the maximum delivery rate obtained by Epidemic algorithm.

GTDM: A DTN Routing on Noncooperative Game Theory in a City Environment

The performance of delay tolerant networks (DTNs) can be influenced by movement model in different application environments. The existing routing algorithms of DTNs do not meet the current city environments due to the large differences in node densities, social characteristics, and limited energy. The key indicators of DTNs such as success delivery ratio, average delivery latency, network lifetime, and network overhead ratio can influence the performances of civil DTNs applications. Aiming to improve the key indicators of DTNs in city environments, this paper presents a fixed sink station based structure and a more proper routing algorithm named Game Theory Based Decision Making (GTDM). GTDM shows decision-making process for neighborhood selection and packet delivering strategy which is based on the noncooperative game theory method and city environment characteristics. GTDM performance is evaluated using numerical simulations under Working Day Movement (WDM) model and the results suggested that GTDM outperforms other traditional DTNs routing approaches, such as Epidemic and Prophet algorithms.

PSaD: A Privacy-Preserving Social-Assisted Content Dissemination Scheme in DTNs

Content dissemination is very useful for many mobile applications, like instant messaging, file sharing, and advertisement broadcast, etc. In real life, for various kinds of time-insensitive contents, such as family photos and video clips, the process of content dissemination forms a delay tolerant networks (DTNs). To improve the data forwarding performance in DTNs, several social-based approaches have been proposed, most of which leverage mobile users' social information, including contact history, moving trajectory, and personal profiles as metrics to design routing schemes. However, although the social-based approaches provide better performance, the revealing of mobile users' information apparently compromises their privacy. Moreover, users' contents may only be shared with a particular group of users rather everyone in the system. In this paper, we propose the PSaD: a Privacy-preserving Social-assisted content Dissemination scheme in DTNs. We apply users' verifiable attributes to establish their social relationships in terms of identical attributes in a privacy-preserving way. Besides, to provide the confidentiality of contents, our approach enables users to encrypt contents before the dissemination process, and only allows users who have particular attributes to decrypt them. By trace-driven simulations and experiments, we show the performance, privacy preservation, and efficiency of our proposed scheme.

Prioritization of Traffic for Resource Constrained Delay Tolerant Networks

In networks with common shared wireless medium, the available bandwidth is always valuable and often scarce resource. In addition to it, memory available at nodes (eg., sensor nodes) might be limited relative to the amount of information that needs to be stored locally. As Delay Tolerant Networks (DTNs) rely on node mobility for data dissemination, the high node mobility limits the duration of contact. Besides the issue of contact opportunities between nodes, the bandwidth, available storage at peering nodes and contact duration also affect data forwarding. These factors also influence the mechanisms such as buffer replacement and scheduling policies. So there are secondary problems that routing strategies may need to take care of such as to deal with limited resources like buffer, bandwidth and power. Furthermore, despite inherent delay tolerance of most DTN driving applications, there can be situations where some messages may be more important than the others and expected to get delivered earlier. So considering the network limitations and application requirements, the problem of choosing the messages to be transmitted when a contact opportunity arises and the messages to be dropped when buffer full is formulated. A buffer management policy to address these issues is proposed and analysed in this paper. Additionally the buffer utilization of various DTN routing protocols and the impact of buffer size on the performance of DTN are studied.

Quota-control routing in delay-tolerant networks

Delay-tolerant networks (DTNs) are network environments that are subject to delays and disruptions. Traditional end-to-end routing protocols fail in such challenging network conditions because of intermittent connections and/or long delays. Research results have shown that per-hop forwarding of multiple copies of the same message to the destination can produce satisfactory routing performance in DTNs. Current methods rely on the fixed setting of a quota value to limit the number of message copies. This paper proposes a dynamic quota-control mechanism, allowing routing to operate effectively with different traffic loads. To remove useless message copies from the network, a low-cost probability-based method is also presented. The proposed routing framework is then extended to interest-based information dissemination, which is used to efficiently disseminate an event message to all interested users. A performance evaluation was conducted using a real social contact trace, and performance comparisons with other DTN routing protocols are provided.

Performance Modeling of Delay-Tolerant Network Routing via Queueing Petri Nets

With the advent of wireless technologies such as Wi-Fi Direct and Near Field Communication (NFC), infrastructure-less Peer-to-Peer (P2P) content sharing among mobile devices is set to become more ubiquitous. Delay-Tolerant Networks (DTNs), with their opportunistic message forwarding strategy, can be leveraged to provide seamless connectivity in such scenarios. To the best of our knowledge, little has been done to understand the performance of DTNs under realistic settings involving the interplay of diverse factors such as bundle fragmentation, scheduling, and buffer spacing. In this paper, we look at Queueing Petri Nets (QPNs) as a modeling framework to study the performance of DTN routing. We develop QPN models for DTNs of increasing complexity in an incremental fashion, starting from a network that employs the rudimentary direct transmission routing protocol to a network that employs a family of multi-hop and replication-based routing protocols (namely (p, q) -epidemic routing). The complete QPN model considers a number of realistic factors that impact performance such as finite buffer space, finite link bandwidth, bundles with different priorities and intra-scheduling delays arising due to different levels of the memory hierarchy at the nodes. We come up with a three-fold validation scheme to assert the veracity of our proposed models, via comparison of results obtained from simulations of the QPN vis-a-vis those obtained from direct simulation of the underlying DTN and experimental results obtained from a testbed of Android based devices that employ a mobility emulation scheme. We also show a case to exemplify the analytical capability of the QPN, by deriving the underlying reachability graph and constructing an equivalent stochastic jump process. We identify the stochastic process to be a Semi-Markov Process (SMP) and hence arrive at a closed form expression for the end-to-end delivery latency by computing the hitting time of the SMP. We find that the model accurately captures the behavior of a DTN in numerous realistic scenarios, showing the efficacy of QPNs as a suitable modeling framework for evaluating the DTN routing protocols.

An energy-aware deadline-constrained message delivery in delay-tolerant networks

In order to understand the message dissemination performance in delay-tolerant networks, much analysis work has been proposed in literature. However, existing work shares a common simplification that the pairwise inter-meeting time between any two mobile nodes is exponentially distributed. Not mention the fact that such assumption is only an approximation, it cannot be applied by network planners to directly control the mobile nodes for any network optimization, e.g., energy efficiency. It is quite significant to study the relationship between the network performance with the parameters that can be adjusted directly to tackle the limitations of current exponential distribution assumption based analysis. Therefore, in this paper, we are motivated to jointly consider the transmission range and messages residence time to stochastically analyze deadline-constrained message delivery ratio utilizing a controlled epidemic routing. The message propagation is considered as an age-structure process and described by a susceptible---infectious---recovered model, which is then analyzed using delay differential equations. Since both the transmission range and the message residence time are related to the mobile nodes' energy consumption, we further apply our analysis framework to investigate the tradeoff between the energy consumption and the achievable message delivery ratio. The correctness and accuracy of our analysis are validated by extensive simulations.

PERFORMANCE EVALUATION OF MOFO BUFFER MANAGEMENT TECHNIQUE WITH DIFFERENT ROUTING PROTOCOLS IN DTN UNDER VARIABLE MESSAGE BUFFER SIZE

Delay Tolerant Networks (DTNs) uses the store-carry-forward scheme for the delivery of the messages, with this way data transmission can be successfully done despite of the absence of continuous end-to-end paths. The opportunities of message forwarding in such types of networks usually are limited due to the absence of contemporaneous paths. In such networks, the “store-carryforward” methodology is used for the transmission of the messages to be delivered to their intend destinations in a hop by hop manner. It arises many problems like how to schedule the messages, how to drop the messages in the buffer due to the impulsive nature of the nodes. It also arises many challengeable situations like short contact durations between the two nodes, limited storage capacity of nodes and so on. This paper evaluates the performance of MOFO buffer management technique with three routing protocols i.e. Epidemic, Prophet and MaxProp under variable message buffer sizes (5MB to 40MB). Such evaluation can improve the performance of the opportunistic networks by reducing the overhead ratio, enhancing the delivery rate, minimizing latency average and hop count average in a certain degree. So four performance evaluation metrics namely delivery probability, latency average, overhead ratio and hop count average are used in this study. This study uses ONE (Opportunistic Network Environment) simulator for the performance evaluation of the MOFO buffer management technique and routing protocols. The evaluation results shows that the performance of different protocols can benefit to optimizing the performance of delay tolerant networks in terms of delivery probability, Latency average, Overhead ratio and Hop count average of messages with the increase in message buffer size. Finally, this study suggested that which routing protocol is most suitable with MOFO buffer management technique.