Buffer Management For Preferential Delivery In Opportunistic Delay Tolerant Networks

Majority of the existing Delay Tolerant Network (DTN) routing protocols, attempt to minimize one of the popular DTN routing indices, i.e. message delay, forwarding count and storage. However, for many DTN applications such as distributing commercial content, targeting the best performance for one index and compromising the others is insufficient. A more practical solution would be to strike a balance between multiple of these indices. Gain Dissemination Protocol (GDP) is one of the protocols which targets this aim by introducing a gain concept which tries reach a maximum gain of delivery by keeping the balance between the value achieved via delivering the packet to the destination and the forwarding cost involved with that. In this paper, we focus on characterizing the GDP protocol in the scope of mobility. We also propose an upper bound for gain in multicast routing problem, i.e. the Union of Unicast Benchmark (UUB) and compare the performance of a few DTN routing protocols with the former. This eventually reveals the performance scope of a potential gain-aware DTN dissemination protocol.

Delay-Tolerant Networks (DTNs) are kinds of networks where there does not exist any complete end-to-end route from source to destination. Such networks can also be referred to as Intermittently Connected Mobile Networks (ICMNs), which are featured by asymmetric data rates, large delay, limited resources and high error rates. In this network, size of buffer and Time-to-Live (TTL) for fixed number of nodes and message generation rates contribute to the network performance because of limited resources and short life span of a packet in the net-work. Therefore, investigating efficient routing for altering TTL and size of buffer is very important for overall network performance. This paper presents a performance analysis based on simulation of the impact of buffer size and TTL for several DTN routing protocols in ICMNs scenario. ONE, i.e., Opportunistic Network Environment is used to simulate the routing protocols considering three performance metrics: delivery ratio, mean latency and overhead ratio. Investigated results mention that Spray-and-Focus (SNF) routing exhibits the best performance for altering TTL and size of buffer than other DTN routing protocols, i.e., Epidemic, PRoPHET, PRoPHETv2, MaxProp, RAPID, and Binary-SNW in the considered performance metrics and simulation scenario.

Generic prediction assisted single-copy routing in underwater delay tolerant sensor networks

SummaryIn Delay Tolerant Networks (DTNs), mobile nodes exploit encounter chances to transmit data via the established opportunistic link between encounter nodes. The transmission capacity between two encounter nodes is constrained by the duration of opportunistic links. How to transmit data efficiently is one of the fundamental and most important issues in DTNs. Recently, Random Linear Network Coding (RLNC) is proposed as a promising approach to improve data transmission efficiency in DTNs. To facilitate the development of deployment of RLNC based routing protocols, it is imperative to quantify the performance gain brought by RLNC in a rigorous and systematic way. In this paper, we develop an analytical model to evaluate the data transmission performance of RLNC based epidemic routing in DTNs. In the model, we consider that multiple unicast communication sessions compete for limited \capacity. Numerical results validate the effectiveness of our analytical model and demonstrate the significant performance improvement for data transmission in DTNs brought by RLNC. Our work of this paper provides a general tool for performance evaluation and useful guidelines for designing RLNC based routing protocols in DTNs. Copyright © 2015 John Wiley & Sons, Ltd.

In challenged networks, such as opportunistic networks or Delay Tolerant Networks (DTNs), due to frequent network partition an end-to-end connection between source and destination may not always be possible due to nodes move unpredictably with high speeds. For such type of networks, traditional routing protocols fails to transmit and also no guarantee on delivery of data to specified destination because these protocols deliver data definitely whenever there exists continuous end-to-end connectivity between source and destination over time. To provide efficient routing for such networks replication based routing schemes were proposed to achieve higher delivery probability. Unlike Internet protocols, Delay Tolerant Networks routing protocols follow store-carryforward mechanism to reduce packets dropping probability, tolerate delays and improve delivery performance in terms of delivery ratio and delivery latency. This paper defines the most efficient replication based routing protocols such as epidemic, PROPHET, spray and wait and Encounter based routing. This paper also explains how message TTL, buffer sizes and area of grid impact performance of replication based routing protocol in terms of delivery ratio and Average latency and overhead ratio.

The Delay Tolerant Networks (DTNs), are emerging as one of the most efficient network that allow nodes in intermittently connected networks to communicate with each other. They are designed to overcome high latency and lack in connectivity due to poor infrastructure and short range radios. However, the DTNs relay nodes have limited resources (i.e., low-power RF module, low computation capacity, limited buffer size, short battery power). Moreover, the DTNs routing protocols, which route the message between a source and a target destination, are very numerous, including the famous Epidemic routing, k-hop routing, prophet routing. Consequently, We found that it would be valuable to compare these prominent opportunistic networks protocols under constraint of energy consumption in forwarding activity. We have done this using the ONE simulator and evaluated the schemes with regard to message delivery probability, energy efficiency.

In delay tolerant networks (DTNs), nodes have intermittent connectivity patterns due to various factors such as mobility, sparse network topology, and unpredictable movement patterns. In such networks, nodes store messages, carry them along as they move and forward them opportunistically whenever an encounter occurs. In many DTN applications, such as in disaster situations and remote regions with no communications infrastructure, we can envisage a network topology formed by the mobility and contact pattern of people carrying their mobile devices. The social behavior of people (nodes) in Spatio-temporal dimensions governs the formation of such a topology. To improve data dissemination in such networks, several works have proposed to utilize social-aware metrics for the selection of relays. However, existing routing protocols for DTNs may perform poorly in the scenarios in which nodes are localized in multiple small regions, and the topology is sparse such as in co-located villages in remote regions with no communication infrastructure. This work proposes a Cooperative mobile throwbox-based routing protocol (CMTR) for social-aware DTNs. In CMTR, static and mobile ThrowBoxes (TBs) are deployed to improve the efficiency of a DTN. The static and mobile TBs cooperatively relay data to enhance network efficiency. Performance evaluation via simulations in ONE simulator shows that CMTR improves the data delivery ratio, delays, and energy efficiency as compared to Epidemic routing and Bubble Rap routing schemes.

In recent years, several investigations have been made on "challenged network" [also known as, delay tolerant network (DTN)] architectures highlighting their advantages and disadvantages. In spite of its inherent shortcomings of unreliability and delay, smart-phone based opportunistic network is gaining immense popularity in the research community due to its applicability in different adverse and extreme communication scenarios where traditional communication infrastructure is either unavailable or incapacitated for a long time. Considerable research has been conducted till date to design efficient network architecture for emergency data dissemination in intermittently connected/challenged networks. Different architectures (ranging from flat to multi-tier) are proposed for implementing opportunistic DTN keeping in view of specific application requirements. However, very few of these proposed architectures have been examined from the perspective of a post disaster communication. Moreover, most DTN architectures are designed by aiming towards increasing delivery probability and reducing latency and as a whole, maximizing network throughput; with very little emphasis on its energy efficiency. The impact of different mobility patterns on existing DTN routing algorithms with respect to data dissemination and energy consumption has also not been studied so far. Our objective, in this paper, is to investigate the impact of different mobility patterns on existing DTN routing protocols and existing DTN architectures and subsequently, come up with a suitable energy efficient DTN framework combining suitable architecture and routing protocol that may be used to offer different disaster management services during post-disaster relief operation. We have done an extensive simulation on ONE simulator with different categories of well-known existing DTN architectures, mobility models, DTN routing protocols to study the network performance in terms of delivery probability, energy efficiency and overhead ratio. Based on the simulation results, we have tried to figure out a suitable combination of energy efficient architecture, mobility model and routing protocol that fits well in the post disaster communication scenario.

In a Delay Tolerant Network (DTN), the nodes have intermittent connectivity and complete path(s) between the source and destination may not exist. The communication takes place opportunistically when any two nodes enter the effective range. One of the major challenges in DTNs is message forwarding when a sender must select a best neighbor that has the highest probability of forwarding the message to the actual destination. However, finding an appropriate route remains an NP-hard problem. This paper presents a concept of Checkpoint (CP) based message forwarding in DTNs. The CPs are autonomous high-end wireless devices with large buffer storage and are responsible for temporarily storing the messages to be forwarded. The CPs are deployed at various places within the city parameter that are covered by bus routes and where human meeting frequencies are higher. For the simulative analysis a synthetic human mobility model in ONE simulator is constructed for the city of Fargo, ND, USA. The model is tested over various DTN routing protocols and the results indicate that using CP overlay over the existing DTN architecture significantly decreases message delivery time as well as buffer usage.

Delay-Tolerant Networks (DTN) are intermittent wireless mobile networks designed to handle communications in environments where network connectivity is often disrupted due to node mobility or the absence of fixed infrastructures.These frequent disconnections lead to repeated communication attempts between nodes, thereby increasing energy consumption.DTN is often deployed in isolated and hard-to-reach environments with limited energy sources, imposing significant constraints on the performance and operational lifetime of individual DTN nodes, as well as the DTN network as a whole.Despite the significant efforts invested by researchers to develop energy-efficient algorithms and models, the problem of energy consumption persists, especially with nonrenewable sources.The motivation for this research is based on the major challenges related to powering mobile nodes in DTN networks, notably due to the absence of reliable and constant energy sources.The energy constraints of the nodes, combined with their mobility, raise problems of energy consumption and durability, leading to communication interruptions, delays, data losses, and a decrease in the overall efficiency of the network.To overcome these challenges, the article proposes a long-term energy management strategy by integrating renewable energy sources, notably solar energy, into the architecture of DTN nodes.The contributions include the modeling of an energyautonomous and sustainable solar-powered DTN node, the evaluation of the energy generated and stored by these nodes, and the validation of the effectiveness of this approach through simulations in the ONE simulator, considering realistic mobility scenarios and communication conditions.The results show that solar DTN nodes have significantly higher residual energy than those with limited power sources.Additionally, social mobility models (MBM, SPMBM) consume more energy than individual models (RW, RWP, RD), while the Spray-and-Wait and PROPHET protocols are more energy-efficient compared to Epidemic and MaxProp.These analyses reveal optimal combinations of DTN protocols and mobility models to reduce energy consumption: the Spray-and-Wait protocol aligns well with social mobility models, while PROPHET is more suited to individual mobility models.

A class of Delay Tolerant Networks (DTN), which may violate one or more of the assumptions regarding the overall performance characteristics of the underlying links in order to achieve smooth operation, is rapidly growing in importance but may not be well served by the current end-to-end TCP/IP model. Delay Tolerant Networks: Protocols and Applications takes you on a systematic exploration of DTN concepts, architectures, protocols, enabling technologies, and applications. Containing a wealth of illustrative material for ease of understanding, this one-stop reference discusses the various challenges associated with DTN. Written for a broad audience of researchers and practitioners, it supplies useful reference material for graduate students and senior undergraduate students in courses of networking, wireless, and mobile communications. Starting with an accessible introduction to DTNs, their architecture, bundle protocols, and routing schemes, the book provides authoritative coverage of: DTN Routing Energy-Aware Routing Protocol for DTNs A Routing-Compatible Credit-Based Incentive Scheme R-P2P: a Data-Centric Middleware for Delay Tolerant Applications Mobile Peer-to-Peer Systems over DTNs Delay-Tolerant Monitoring of Mobility-Assisted WSN Message Dissemination in Vehicular Networks DTN Protocols for Space Communications DTN for Satellite Communications Reporting on the latest developments in these domains, the distinguished panel of contributors supplies a realistic look into the future of networking. Complete with sections that summarize open issues in each domain, this book arms you with the understanding and methods required to make an impact on the advancement of these emerging networks that continue to grow in importance.

In delay tolerant networks (DTNs), all the networking functions rely on the contribution of the participants to fulfill the store-and-forward fashion. Since wireless nodes are buffer and energy constrained, it may not be in the best interest of a node to always accept relay request. In recent years, incentive mechanisms have been proposed to stimulate nodes to cooperate in packet forwarding. However, the lack of end-to-end paths, high variation and long feedback delay in DTNs imply that existing solutions for mobile ad-hoc networks do not apply to DTNs. In this paper, we address the problem assuming that nodes are rational to optimize self interest. We propose a model, named Pay-for-Gain (PFG), based on game theory and loan-credit theory, to investigate equilibrium point that maximizes their own interest. For comparison, the strategy tit-for-tat (TFT) and PFG are tested in existing routing protocols in DTNs.

The underwater acoustic channel features long and variable propagation delay, high bit error rate and limited bandwidth. Moreover, underwater mobile networks consisting of Autonomous Underwater Vehicles (AUVs) for surveillance and monitoring applications often suffer from intermittent connectivity as nodes move around the area of operations. Therefore, this scenario is appropriately modeled as a Delay-Tolerant Network (DTN). In this paper, we investigate two classes of DTN routing protocols: Spray-and-Wait (SNW) and the Resource Allocation Protocol for Intentional DTN (RAPID), together with a standard flooding protocol for underwater mobile networks, and their performance is analyzed in terms of packet delivery ratio, average end-to-end delivery delay and throughput, in different load conditions across various node mobility scenarios. Our results show that RAPID performs better than other DTN routing protocols in terms of packet delivery ratio at higher load conditions irrespective of node mobility, whereas the Binary version of SNW has the best performance in terms of average delivery delay.

Delay tolerant networks (DTNs) are wireless networks where disconnections may occur frequently due to node mobility, power outages and propagation phenomena. To achieve date delivery, store-and-forward protocols are used in DTN and routing protocols based on epidemic message dissemination have been proposed, like epidemic routing. Under epidemic routing, messages can be delivered completely between every two nodes if every node buffer is big enough and the communication time is long enough after one node contacts another. But congestion will occur easily at a node if the buffer of this node is limited under epidemic routing in DTN. To solve this problem, a novel congestion control strategy is introduced. The strategy is called N-DC (drop the copying numbers over N). By using simulations based on a Random Waypoint model, the simulation results proved the improvement of this strategy.

Epidemic Routing is an original and effective multicopy routing algorithm in disruption tolerant networks. However, its performance degrades significantly when network resources are limited. In this paper, we proposed a new routing scheme, called Weighted Epidemic Routing (WER). WER appropriately arranges the priority of messages for forwarding or deleting through assigning a weight for each of them when the buffer size of nodes and contact duration are limited. The weight of a message is determined by TTL and replications density that is a novel metric to estimate the amount of copies around an infected node. Meanwhile, an ACK vector exchange mechanism is employed by WER to purge the redundant messages. Simulation results show that WER outperforms Epidemic with Drop-tail and FIFO drop policy by a factor of about 6.8 and 0.66 respectively when buffer size is low.