A comparative study on delay-tolerant network routing protocols

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.

Unmanned Arial Vehicle (UAV) Network is an autonomous wireless communication network, mainly used for natural disaster recovery operations to forward the captured images or video information to the ground vehicle. The UAV network can be applied in various applications essentially, search and rescue operations. This work concentrates on Delay Tolerant Network DTN based Decentralized Multi-layer UAV ad-hoc network assisting VANET for post-disaster scenarios. Because of unbalanced links in highly dynamic UAV networks, packet forwarding is a challenge. This work proposes a Binary Spray and wait routing protocol (BSnW) with controlled replication for DTN based Decentralized Multi-layer UAV networks. The Next Layer UAVs are presented to empower a well-organized Store and carry forward (SCF), in Multi-Layer UAV ad-hoc networks. Next Layer UAVs expands the accessibility of connecting tracks among the all DTN UAVs and the ground vehicle, hence reducing end-to-end delays and growing the packet delivery ratio and drop the packet drop ratio. The proposed BSnW with controlled replication protocol enables a high packet delivery ratio, which enables, and guarantees single-copy data forwarding to evade duplication of every message. Proposed protocol has been experimented using Opportunistic Network Environment (ONE) Simulator. Our simulated experiment show that the proposed protocol outstrips the epidemic routing protocols reported in the literature in terms of the packet delivery ratio, average delay, throughput and the routing overhead.

Intermittently Connected Mobile Networks (ICMNs) are sparse wireless networks where most of the time an end-to-end path does not exist from source to destination. These networks are characterized by opportunistic connectivity, long and variable delay, asymmetric data rate and high error rate. Hence, they can be appropriately modeled as Delay-Tolerant Networks (DTNs). In this paper, the performance of replication-based DTN routing protocols, namely Epidemic, PRoPHET, MaxProp, RAPID, Binary Spray-and-Wait, and Spray-and-Focus has been investigated in an ICMN scenario against varying message generation rates and number of mobile nodes, respectively. The performance is analyzed on the basis of three metrics: Delivery Probability, Average Latency, and Overhead Ratio. Opportunistic Network Environment (ONE) simulator is used as the simulation tool for evaluating these performance metrics. The outcome of this work shows that for the ICMN scenario and given simulation setting, the best DTN routing technique is Spray-and-Focus, whereas Epidemic routing exhibits the worst performance in terms of all the metrics considered here.

The heterogeneous networks are those which can connect different devices running with different operating systems and using different protocols. The main problem with these networks is network connectivity. In order to ensure the continuous network connectivity between the nodes, the Delay Tolerant Networks (DTNs) are useful as they operate on extreme distances and depend up on the changing positions of the nodes. The Epidemic Routing Protocol (ERP) makes use of DTN concept. The previous works show the performance of Epidemic Routing Protocol in terms of packet delivery ratio, end-to-end delay, and energy consumption. In this work, the Epidemic Routing Protocol's performance for Delay Tolerant Networks will be evaluated by considering different parameters like, Average Latency, Energy Balancing Factor, and Number of Alive and Dead nodes.

Nowadays, Vehicle Ad Hoc Networks (VANETs) have become a new trend and one of the most attractive areas of research. It has a wide range of applications such as smart cities and the Internet of Things (IoT). The main issue of the VANET networks is the limitation in network resources such as power, and memory. Moreover, since VANET nodes are dynamic and move over time, the connectivity of the networks is also considered an important issue. This paper designs experiments that reflect a variety of scenarios in VANET networks. Many issues and factors in VANET networks have also been investigated in this paper. There are many factors that affect the whole performance of VANET networks (i.e., mobility models, routing protocols, and things distribution) in terms of network resources. Therefore, this paper aims at testing different mobility models such as the Human Mobility model, Cauchy Flight Mobility model, and Correlated Directions Mobility model, and investigate their impact on the consumption of network resources under a particular routing protocol such as Spray and Wait routing protocol, Probabilistic Flooding routing protocol, and Epidemic routing protocol. In addition, testing different distributions such as Uniform distribution, Gaussian (Normal) distribution, and Power-Law distribution). The resources we plan to investigate are energy sources and the amount of data exchanged. In the designed experiments, each simulation includes a combination of a mobility model, nodes distribution, and a routing protocol. The findings showed that each mobility model, routing protocol, or distribution is effective in a particular application. As a result, it was found that determining the application of the VANET network is a crucial step before performing a simulation or designing a network.

Delay Tolerant Networks enable data transmission in different applications, mainly in environments where communication infrastructure is missing. The existence of links is casual and even when links are created, they are short in time and unstable/unreliable in terms of connectivity. Thus, underwater network applications tend to be delay tolerant. In this paper, we propose a mobility-aware routing protocol for underwater wireless sensor networks. The protocol is based on Focused Beam Routing (FBR) protocol and considers nodes’ next destination location when making forwarding decisions. The routing protocol is called Destination-aware Focused Beam Routing (D-FBR) protocol and we compare its performance with FBR protocol for different FBR angles and different applications. We use Delivery Probability (DP), Average Number of Hops (ANH), Overhead Ratio (OR) and simulate our scenarios by The ONE simulator. Simulation results show that, for D-FBR protocol, when FBR angle is 30 ∘ , OR and ANH is improved by 34.5 % and 23.1 %, respectively, while DP is 6.5 % lower, compared to FBR protocol. Both D-FBR and FBR outperform Epidemic Routing Protocol.

Delay Tolerant Network(DTN) is a wireless network where source cannot have a handshake with the destination and source has to use a routing known as opportunistic routing to deliver the message to the destination. One of the most widely used routing protocol in DTN is Spray and Wait(SnW) routing protocol and there are a lot of methods to complete the spray phase, most popular is Binary SnW. In this paper, we are proposing a modified version of Binary SnW protocol referred as Hexago SnW. In this approach, we used hexagonal series instead of binary series. The comparison of Hexago SnW with other existing approaches shows that Hexago SnW gives better performance than others in term of overhead ratio, delivery ratio etc. In simulation, two groups of moving objects are used to show the working and performance evaluation of our proposed routing technique.

Intermittently connected opportunistic networks experience frequent disconnections and shorter contact durations. Therefore routing of messages towards their destinations needs to be handled from various points of view. Predictability and connectedness are two information which can be determined by participating mobile nodes of an opportunistic content distribution network using their past contacts. Epidemic or probabilistic routing protocols do not fully utilize these information to route messages towards their destinations. In this paper we describe the routing algorithm, implementation details, experiment design and the performance validation of a new, adaptive routing protocol which utilizes the predictability and connectedness information to route messages efficiently. Simulation based comparative studies show that the proposed routing protocol outperforms existing Epidemic and probabilistic routing protocols in delivering messages.

Research on vehicular ad hoc networks (VANETs) has focused primarily on efficient routing protocol design under conditions where there are relatively large numbers of closely spaced vehicles, typical of major highways and urban areas. These routing protocols are designed principally for fully connected networks and are not suitable for packet delivery in a sparse, partially connected VANET. In rural areas, vehicle densities are low and roadway communication infrastructure is scarce, leading to long periods where vehicle-to-vehicle or vehicleto- roadside communications is infrequent, interrupted, or simply not possible. These attributes characterize a sparse VANET, and are characteristic of delay tolerant networks (DTNs). In this paper, we examine the challenges of VANETs in sparse network conditions, review alternatives including epidemic routing and propose a Border node Based Routing (BBR) protocol for partially connected VANETs. Unlike many VANET protocols that assume location awareness or mobility patterns to aid in routing decisions, BBR is designed to function in domains where location and mobility information is not available, as is typical in rugged terrain conditions. The BBR protocol can tolerate network partition due to low node density and high node mobility. The performance of this protocol is evaluated in OPNET TM with a Random Waypoint mobility model and a Geographic and Traffic Information (GTI) based mobility model that captures typical highway conditions. The simulation results are compared with those obtained using the Dynamic Source Routing (DSR) protocol and with an epidemic routing protocol. The simulation results show that BBR performs well for partially connected VANETs where other protocols fail and provides the advantage of not relying on a location service required by other protocols proposed for VANETs.

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 this paper, we evaluate and compare the performance of single-copy and multiple-copy routing protocols in a realistic Vehicular Delay Tolerant Network (VDTN) scenario. The simulations are conducted with the Opportunistic Network Environment (ONE) simulator. The performance is analyzed using delivery probability, overhead ratio, average latency, average number of hops and average buffer time metrics. The simulation results show that multiple-copy protocols perform better in terms of delivery probability compared with singlecopy protocol. The single-copy protocol uses the highest average number of hops and higher average latency compared with multiple-copy protocols. Maxprop achieves the highest delivery ratio and lowest average latency. Spray and wait results are the lowest for overhead ratio, but the longest for average buffer time. First contact have a short buffer time, but it uses a big number of hops.

Hybrid delay tolerant network routing protocol for heterogeneous networks

Delay Tolerant Network (DTN) has the potential to connect nodes in an environment where an end-to-end path may not be available between source and destination. Resources constraint is among the most serious issues in DTN. In this paper, we consider the scenario where we want to transmit an information (message) from a source to a group of people in the network area. Using the epidemic routing protocol the message can reach its destinations as fast as possible, but the protocol consumes too much resources. We model the messages propagation under the epidemic routing protocol by an Ordinary Differential Equation (ODE). And, we derive the optimal retention of a message by a node, taking into account that all nodes are infected. Simulations results show that, using the proposed optimal control in epidemic routing context, we can reach the same performances of epidemic routing while minimizing the resource consumption.

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.

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.