An Improved Opportunistic Routing Protocol for Intermittently Connected Delay Tolerant Wireless Sensor Networks

Delay tolerant network (DTN) protocol was proposed for a network where connectivity is not available. In DTN, a message is delivered to a destination node via store-carry-forward approach while using opportunistic contacts. Probabilistic routing protocol for intermittently connected networks (PRoPHET) is one of the widely studied DTN protocols. In PRoPHET, a message is forwarded to a contact node, if the contact node has a higher delivery predictability to the destination node of the message. In this paper, we propose an improved opportunistic routing protocol, where context information of average distance travelled and average time elapsed from the reception of a message to the delivery of the message to the destination node is used. In the proposed protocol, the average distance and average time are updated whenever a message is delivered to a destination node. Then, both average distance and average time as well as delivery predictability of PRoPHET protocol are used to decide a message forwarding. The performance of the proposed protocol is analyzed and compared with that of PRoPHET and reachable probability centrality (RPC) protocol, which is one of the latest protocols using the contact history information of a mobile node. Simulation results show that the proposed protocol has better performance than both PRoPHET and RPC, from the aspect of delivery ratio, overhead ratio, and delivery latency for varying buffer size, message generation interval, and the number of nodes.

One of the challenges in Delay Tolerant Wireless Sensor Networks (DT-WSN), is to handle situations where the available buffer space is insufficient- the buffer management problem. Although several buffer management algorithms have been proposed for DT-WSNs, to the best of our knowledge, there is no comprehensive study on the effects different factors have on their performance, and which evaluates the relative performance of these algorithms in different contexts. This paper evaluates in a fixed-factor factorial experiment the performance in terms of latency and Quality of Information (QoI) of four representative buffer management algorithms for DT-WSNs; two traditional, FiFO and Random, and two QoI-based algorithms- one proposed by Humber and Ngai and the SmartGap algorithm. The evaluation suggests that the buffer management algorithm in combination with employed routing protocol and the sensor node buffer sizes have a significant impact on latency, while the obtained QoI rather depends on the characteristics of the transported data and the routing protocol, provided a single-copy routing protocol is used. Moreover, the evaluation suggests that QoI-based buffer management algorithms do offer improved QoI, with an 31% improvement in MAE for SmartGap compared to FIFO. However, they do so at the expense of higher latency, with SmartGap giving a 60% higher latency than FIFO on average.

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.

Delay tolerant networking (DTN) is proposed to deliver message successfully, even in an extreme environment, where network connectivity is not guaranteed. In this paper, we consider group mobility model and propose a novel protocol for group mobility in DTN. Simulation results show that the proposed protocol has better delivery ratio and overhead ratio than PRoPHET protocol.

RFID enabled wireless sensor networks are attracting intensive interests of intelligent transportation applications. This paper proposes a dynamic infrastructure for vehicular communications built upon the RFID enabled delay tolerant wireless sensor networks named mobile relay network (MRN) for the communication in the intelligent transportation system. A group-sequence based routing protocol is developed to support the MRN. Based on the MRN, the Ubiquitous Intelligence for Data Query (UIDQ) service platform is proposed to provide information access, relay, search and delivery among the drivers on the move. The computing results validate the UIDQ scheme.

Delay tolerant networks (DTNs) are wireless networks in which an end-to-end path for a given node pair can never exist for an extended period. It has been reported as a viable approach in launching multiple message replicas in order to increase message delivery ratio and reduce message delivery delay. This advantage, nonetheless, is at the expense of taking more buffer space at each node. The combination of custody and replication entails high buffer and bandwidth overhead. This paper investigates a new buffer management architecture for epidemic routing in DTNs, which helps each node to make a decision on which message should be forwarded or dropped. The proposed buffer management architecture is characterized by a suite of novel functional modules, including Summary Vector Exchange Module (SVEM), Networks State Estimation Module (NSEM), and Utility Calculation Module (UCM). Extensive simulation results show that the proposed buffer management architecture can achieve superb performance against its counterparts in terms of delivery ratio and delivery delay.KeywordsRoutingBuffer management

Limited memory capacity is one of the major constraints in Delay Tolerant Wireless Sensor Networks. Efficient management of the memory is critical to the performance of the network. This paper proposes a novel buffer management algorithm, SmartGap, a Quality of Information (QoI) targeted buffer management algorithm. That is, in a wireless sensor network that continuously measures a parameter which changes over time, such as temperature, the value of a single packet is governed by an estimation of its contribution to the recreation of the original signal. Attractive features of SmartGap include a low computational complexity and a simplified reconstruction of the original signal. An analysis and simulations in which the performance of SmartGap is compared with the performance of several commonly used buffer management algorithms in wireless sensor networks are provided in the paper. The simulations suggest that SmartGap indeed provides significantly improved QoI compared the other evaluated algorithms.

Usage of wireless gadgets is increasing day by day in both metropolitan and countryside localities. The network infrastructure does not reach all the localities; especially in rural areas, where the internet availability is inadequate to meet the network requirements. Devices in such rural locations will be out of the network for some period. This non-persistent connectivity problem can be solved by using the moving nodes as a carrier for data transmission. In this work, we classify the vehicular network into sparse, semi-sparse and dense network based on the number of static and moving nodes present in a location. In sparse and semi-sparse network, there won't be any continuous path between the source and destination nodes. In such networks, we can use Delay Tolerant Network (DTN) protocols for data transmission. In our work, we try to find the suitable DTN protocol for the sparse and semi-sparse network topology. The protocols considered in this work are Epidemic, Spray and Wait, and Maxprop and the parameters we analyzed are delivery ratio, average latency and overhead ratio. We simulated these protocols in a vehicular network with heterogeneous characteristics, for the dense, semi-sparse and sparse network topology. The routing protocols performance is analyzed by delivery ratio, average latency and overhead ratio using Opportunistic Network Environment (ONE) simulator for varying the message lifetime and node density.

DTNs (Delay Tolerant Networks)refer to the networks that can support data transmission in the extreme networking situations such as continuous delay and no connectivity between ends. DTMNs (Delay Tolerant Networks) are a specific range of DTNs, and its chief considerations in the process of message delivery in the routing protocol are the transmission delay, improvement of reliability, and reduction of network loading. This article proposes a new LCN (Largest Common Neighbor nodes) routing algorithm to improve Spray and Wait routing protocol that prevents the generation of unnecessary packets in the network by letting mobile nodes limit the number of copies of their messages to all nodes to L. Since higher L is distributed to nodes with directivity to the destination node and the maximum number of common neighbor nodes among the mobile nodes based on the directivity information of each node and the maximum number of common neighbor nodes, more efficient node transmission can be achieved. In order to verify the proposed algorithm, DTN simulator is designed by using ONE simulator. According to the result of the simulation, the suggested algorithm can reduce average delay and unnecessary message generation.KeywordsDelay Tolerant NetworksDTMNsMobilityRouting ProtocolONE simulator

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.

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

As the percentage of Vehicles are increasing on roads, Vehicular Ad-hoc network have reached to a significant interest of the researcher in recent times. V2V network and V2I are prominent as an organized solution for attaining safety for moving vehicles on road and transmitting data for a secure journey while driving and transferring data in the form of message from one vehicle to other. VDTN is a kind of Delay Tolerant Networks (DTNs), to provide reliable and efficient communications. Various routing protocols have been used previously in VDTN to enhance the performance of the network in terms of forwarding information in the form of messages to their preferred locations. In this paper, we introduce a novel protocol called Buffer-Efficient Disruption Tolerant Routing Protocol (BEDTRP) to improve delivery delay, overhead and latency. This protocol significantly improves the communication performance such as delivery ratio and overhead in terms of increasing buffer size and bandwidth. Evaluation results show that the proposed method BEDTRP achieves high bandwidth utilization performance to provide better delivery ratio, lower delivery delay, and low overhead against buffer changes. We used ns-2 network simulator to implement Delay tolerant network protocol.

While portable and wireless devices are pouring, a new network technology is needed as a breakthrough. The new network technology features large delays, intermittent connectivity, and absence of an end-to-end path from sources to destinations. A network which has one of those characteristics is called DTNs(Delay Tolerant Networks). The main 4 routing methods have been researched so far in extreme environment. In this paper, we look into the reliability of DTMNs(Delay Tolerant Mobile Networks) in several different situations, and propose an algorithm that selects a positive routine by sending the only information of its position when making a connection to a detected node. We simulate the proposed algorithm here in DTN using ONE simulator. As a result, it shows that the algorithm reduces the number of message transmission each node.

Networks that lack continuous connectivity among their nodes due to node mobility, limited data storage space and constrained power sources are called Delay Tolerant Networks (DTNs). DTN nodes store and carry the data packets until they come into the communication range of each other. In recent years several protocols have been developed specifically for routing in DTNs. These protocols vary in number of copies they use and the kind and amount of knowledge they use to guide the packets to their destinations. Remaining energy level, average latency, overhead ratio and delivery ratio are some of the performance metrics used to measure the performance of these protocols. The existing protocols are good in some of these metrics but not all of them. There is always a trade-off between different performance metrics. In this paper we have proposed a Hybrid protocol utilizing advantages of two protocols namely Epidemic and Probabilistic Routing. The performance is discussed and compared of these protocols with our Hybrid strategy in Opportunistic Network Environment tool.

The intermittent connectivity network under delay tolerant networks is called opportunistic network (OppNet), where there is no direct path between source and destination and does not rely on any central authority. Nodes exchange messages through intermediate nodes in which the message stores waiting for the opportunity to be forwarded to the destination or other cooperative nodes using the concept of store-carry-forward approach. In such a scenario, some critical issues will occur like a low delivery ratio, a long delay, frequent partitions, buffer space management issues. The propsoed research work can overcome all the above issues by designing the routing protocols and many protocols have been proposed based on various techniques like fuzzy logic, neural network, genetic algorithm, machine learning, etc. This paper discusses the opportunistic routing protocols using the concept of fuzzy logic and summarizing them based on their features trying to cover most of the opportunistic routing protocols based on fuzzy logic. This paper classifies the fuzzy logic-based opportunistic routing protocols into two categories, the first one is the message priority and the second is the node selection. The motivation of this paper is to give a wide view of the existing OppNet routing protocols which use the concept of FLC and routing features of each one. This work will allow researchers to find out the appropriate protocol to considered in their research.