Wait, focus and spray: efficient data delivery in wireless sensor networks with ubiquitous mobile data collectors

With decrease in the cost and the size of sensor devices, we can envision a world of ubiquitous sensor networks. Usually, sensor data needs to be disseminated from the source to data collectors, making the spatially distributed sensor data available for applications. The widespread and ubiquitous nature of mobile devices, e.g., PDAs and cell phones around the world, makes them attractive to be used as mobile data collectors (MDCs) to collect and deliver the sensor data. The goal of this work is to design a dissemination protocol that leads to efficient data delivery from the source sensors to ubiquitous MDCs. We propose the Wait-Focus-Spray (WFS) data delivery scheme for wireless sensor networks with ubiquitous MDCs. The main objective of WFS is to balance the data delivery latency and transmission overhead when considering the existence of ubiquitous MDCs. In WFS, we also propose a corresponding mechanism-probabilistic scattered binary spraying (PSBS), to reduce the spatial redundancy when spraying data copies, which can increase the probability of meeting a MDC. We then present an analytical model based on the Markov chain model to analyze the trade-off between delivery latency and transmission cost in WFS. Through extensive simulations, we demonstrate that our proposed scheme reduces the transmission cost per message while provides comparable delivery delay compared with the alternative approach.     

Integrated Social and QoS Trust-Based Routing in Delay Tolerant Networks

We propose and analyze a class of integrated social and quality of service (QoS) trust-based routing protocols in mobile ad-hoc delay tolerant networks. The underlying idea is to incorporate trust evaluation in the routing protocol, considering not only QoS trust properties but also social trust properties to evaluate other nodes encountered. We prove that our protocol is resilient against bad-mouthing, good-mouthing and whitewashing attacks performed by malicious nodes. By utilizing a stochastic Petri net model describing a delay tolerant network consisting of heterogeneous mobile nodes with vastly different social and networking behaviors, we analyze the performance characteristics of trust-based routing protocols in terms of message delivery ratio, message delay, and message overhead against connectivity-based, epidemic and PROPHET routing protocols. The results indicate that our trust-based routing protocols outperform PROPHET and can approach the ideal performance obtainable by epidemic routing in delivery ratio and message delay, without incurring high message overhead. Further, integrated social and QoS trust-based protocols can effectively trade off message delay for a significant gain in message delivery ratio and message overhead over traditional connectivity-based routing protocols.     

Selective Message Forwarding in Delay Tolerant Networks

It is challenging to deliver messages in a network where no instant end-to-end path exists, so called delay-tolerant network (DTN). Node encounters are used for message forwarding. In this paper, we propose a DTN routing protocol SMART. SMART utilizes the travel companions of the destinations (i.e. nodes that frequently meet the destination) to increase the delivery opportunities while limiting message overhead to a bounded number. Our approach differs from related work in that it does not propagate node encounter history nor the delivery probabilities derived from the encounter history. In SMART, a message source injects a fixed number of message copies into the network to forward the message to a companion of the destination, which only forwards the message to a fixed number of the destination’s companions. Our analysis and simulation results show that SMART has a higher delivery ratio and a smaller delivery latency than the schemes that only use controlled opportunistically-forwarding mechanism and has a significantly smaller routing overhead than a pure flooding scheme.     

The multi-copy diversity for routing in sparse vehicular ad hoc networks

The need for routing based on store-and-carry forwarding has been motivated in sparse vehicular ad hoc networks (VANETs), since the traditional end-to-end unicast routing is infeasible due to the network disconnection problem. In store-and-carry based routing, the end-to-end message delivery delay is dominated by the store-and-carry procedure rather than the wireless transmission. Therefore, the end-to-end delay in such sparse VANETs can be further reduced by replicating multiple copies of the message to other nodes when possible, i.e., multi-copy routing, to increase the chance of finally finding the destination, which we call this gain as multi-copy diversity. In this paper, we present an analytic framework to evaluate the performance of routing by assessing the multi-copy diversity gain in sparse VANETs. By using this model, we first derive an upper and lower-bound of end-to-end routing delay in sparse VANETs. Our analytic results show that a high level of multi-copy diversity gain is achieved when the network is partially connected, which is in contrast to the conventional expectation that multi-copy routing performs better in severely disconnected networks. Second, we propose a new adaptive multi-copy VANET routing scheme called AMR by exploiting these analytic results. AMR adapts to the local network connectivity and increases the level of multi-copy diversity at significantly reduced routing overhead compared to the well known epidemic routing. We validate the accuracy of our analytic model and the performance of AMR via simulation studies.     

Mitigating jamming attacks in wireless broadcast systems

Wireless communications are vulnerable to signal jamming attacks. Spread spectrum mitigates these attacks by spreading normal narrowband signals over a much wider band of frequencies and forcing jammers who do not know the spreading pattern to expend much more effort to launch the attack. In broadcast systems, however, jammers can easily find out the spread pattern by compromising just a single receiver. Several group-based ideas have been proposed to deal with compromised receivers; they can tolerate up to t malicious receivers by adding 2t extra copies for each broadcast message. In this paper, we propose a novel scheme with random channel sharing. This scheme reduces the communication cost from 2t to (1 + p)t extra copies, where p determines the channel sharing probability (0 < p < 1). In addition, it does not increase the hardware complexity as it does not require a receiver to operate on multiple channels at the same time.     

Impact of Bloom Filter on Infection Rate in Epidemic Forwarding for ICNs

Mobile ad hoc routing protocols fails in intermittently connected networks (ICN) (i.e. characterized by short-range communication and absence of connected path from source to destination). However, Epidemic routing techniques ensures eventual message delivery from source to destination even where there is never a connected path or when a network partition exists at the origin of message. Epidemic Routing uses random pair-wise messages exchanges between nodes with goals to maximize message delivery rate, minimize message latency, and the total resources consumed in message delivery. Epidemic routing uses summary vector to avoid useless transmission and redundancy. Further,to make summery vector efficient, epidemic routing can use bloom filter to significantly reduce the useless transmissions associated with the summary vector. However, the challenge for epidemic routing remains opens is to optimal design of summary vector size for finite buffer while keeping the benefits of infinite buffer space. This paper proposes an improved scheme of Bloom filter (named it modified bloom filter MBLF), which is tailored according to epidemic routing. We performed simulation to support our clam and observed that delivery ratio of MBLF with epidemic routing is 19 % higher then the traditional bloom filter. In this paper, we have proposed a bloom filter based epidemic forwarding for ICNs.     

Threshold based locking routing strategy for delay tolerant network

Delay tolerance network probabilistic routing protocols forward message to a node by observing its predictability value to meet the message destination. However, it is vital to predict the ability of node to carry the transmitted message. For instance, the traffic confluence on the high probable nodes can produce congestion that results in the drop of previously stored messages. These drops diminish the delivery ratio because the dropped message lost its opportunity to be delivered. Since, there exist multiple copies of each message; therefore, the same node invariably receives the dropped messages from other parts of the network and causes the highest number of transmissions. Additionally, the replication from source node continues on the high probable peers even the previous copies were transmitted on the better predictable neighbors than the current. In this paper, we have proposed a novel routing method called as the adaptive threshold based locking method that maintains the contemporary status of the node based on its activity in the network. We have used the adaptive status measuring metrics such as transmit factor, drop factor and hop away count. Moreover, a threshold based locking method has been introduced to control the diffusion of messages. We have performed the comparison of existing and proposed routing methods with real time mobility traces. The proposed strategy has bolstered the delivery ratio and minimizes hop count, end-to-end delay and number of transmission.     

自适应喷雾聚焦机会网络路由算法

针对现有喷雾路由算法不能依据实际情况动态调整消息拷贝数,而导致资源浪费的问题,提出一种自适应喷雾聚焦路由算法ADPSF。ADPSF依据节点密度估算消息拷贝数,依据相遇概率历史信息选择中继节点和分配消息副本数。仿真试验表明,ADPSF算法在保证消息交付率和时延的情况下有效降低网络开销。     

Sharing spray and wait routing algorithm in opportunistic networks

Due to the instability and intermittent connectivity of links among the nodes and the lack of connectivity in opportunistic network, it is not feasible to use common routing for delivering messages. The only practical method for routing and delivering messages is to use the store-carry-forward routing method. As a case in point, spray and wait is considered to be one of the most appropriate routing methods. The efficiency of this method depends directly on the proper selection of the next hop and the number of copies when it encounters a node. In this paper, a method was proposed that constantly selects the next node and considers the number of copies a node can deliver. In the proposed method, the selection of the next node and the number of message copies to be transmitted by the next hop are based on message carrying time and the probability of message delivery. The network model, based on Markov chain, is extended for analysis. Simulation and analysis results showed that significant enhancement is obtained with the proposed method when measuring metrics such as delay, delivery ratio and copy do comparisons with similar methods.     

延迟容忍移动传感器网络中基于概率复制的数据传输策略及其性能研究

该文提出了一种基于概率复制的数据传输策略PRD(Probability Replication Delivery scheme)用于空间中间断连通的延迟容忍移动传感器网络(DTMSN)数据传输。PRD由选择复制策略和队列管理组成,前者根据节点将消息传递给汇聚点的可能性,选择下一跳进行复制传输;队列管理则利用引入传输概率及复制数的消息生存时间决定队列中消息丢弃原则。仿真分析表明,与现有的几种数据传输策略相比,PRD能以较低的数据复制数及传输延迟获得较高的数据传输成功率。     

DFEMD: Delay Tolerant Fast Emergency Message Dissemination Routing Protocol

In vehicular ad-hoc network, vehicles are move very speedy thus their topology is changing frequently and intermittent connectivity occur often. The intermittent connectivity network (delay and disruption-tolerant network) resulting is end to end path is absent. In this intermittent network connectivity areas, during emergency event occurs, emergency rescue message (Example: Fire, Accident, etc.,) are sent to a rescue team is most necessary. Due to these constraints, general ad hoc protocol approaches is not suitable and, as a result, alternative protocol must be deliberated. This leads to the make a specific protocol mechanisms able to deliver both fast and trustworthiness in-order delivery emergency message needed. Thus we introduce the DFEMDR protocol, it follow the vehicular delay tolerant network (VDTN) common technique store carry-forward method and message replicas. This paper describes an efficient Delay tolerant Fast Emergency Message Dissemination Routing Protocol, called DFEMD routing protocol. This protocol enables in VDTN, the source node broadcast an emergency message to all available node in its communication range. The source node allocates a message replicas and message time to live to the neighbour nodes (forwarded node) based on that node has credence value. Credence value is calculated to all nodes based on two values; the first value is visited level estimation, it is calculated based on the number of nodes previously visited by the node. The second value is Destination Reaches Level Estimation (DLE); it is calculated based on the number of times the node successfully delivered the message to the destination. Finally, each node credence value is calculated, from this visited level and destination reaches level estimation values. Finally, the trust authority received emergency messages and evaluate the trustworthiness of message based on message reputation value or message confidence value.

     

Secure Multi-copy Routing in Compromised Delay Tolerant Networks

Routing in delay tolerant networks (DTNs) is challenging due to their unique characteristics of intermittent node connectivity. Different protocols (single-, multi-copy, erasure-coding-based etc.) utilizing store-carry-and-forward paradigm have been proposed to achieve routing of messages in such environments by opportunistic message exchanges between nodes that are in the communication range of each other. The sparsity and distributed nature of these networks together with the lack of stable connectivity between source destination pairs make these networks vulnerable to malicious nodes which might attempt to learn the content of the messages being routed between the nodes. In this paper, we study DTNs in which malicious nodes are present, to which we refer to as compromised DTNs. We discuss and analyze the effects of presence of malicious nodes on routing of messages in compromised DTNs. We propose a two period routing approach which aims at achieving the desired delivery ratio by a given delivery deadline in presence of malicious nodes. Our simulation results with both random networks and real DTN traces show that, with proper parameter setting, the proposed method can achieve delivery ratios which surpass those reached by other algorithms by a given delivery deadline.     

Optimal Routing Control in Delay Tolerant Networks with Time-Varying Fees

Due to the uncertainty of the connections in delay tolerant networks, the source may need help from other nodes and make these nodes serve as relays to forward the messages to the destination. To further improve the performance, the source may also make these nodes serve as agents, which can help the source to make other nodes serve as relays. However, nodes may not be willing to help the source without any reward because of the selfish nature. This means that the source has to pay certain reward to the nodes that provide help. Furthermore, such fees may be varying with time. For example, if the nodes guess that the source is eager to transmit the message to the destination, they may ask for more reward. In addition, the reward that the source obtains from the destination may be varying with time, too. For example, the sooner the destination gets the message, the more reward may be. In such complex case, it may not be good for the source to request help all the time. This paper proposes a unifying theoretical framework based on Ordinary Differential Equations to evaluate the total reward that the source can obtain. Then, based on the framework, we study the optimal control problem by Pontryagin’s Maximum Principle and prove that the optimal policy confirms to the threshold form in some cases. Simulations based on both synthetic and real motion traces show the accuracy of the framework. Furthermore, we demonstrate that the performance of the optimal policy is the best through extensive numerical results.     

HVE-mobicast: a hierarchical-variant-egg-based mobicast routing protocol for wireless sensornets

In this paper, we propose a new mobicast routing protocol, called the HVE-mobicast (hierarchical-variant-egg-based mobicast) routing protocol, in wireless sensor networks (WSNs). Existing protocols for a spatiotemporal variant of the multicast protocol called a “mobicast” were designed to support a forwarding zone that moves at a constant velocity, \(\stackrel{\rightarrow}{v}\), through sensornets. The spatiotemporal characteristic of a mobicast is to forward a mobicast message to all sensor nodes that are present at time t in some geographic zone (called the forwarding zone) Z, where both the location and shape of the forwarding zone are a function of time over some interval (t _start ,t _end ). Mobicast routing protocol aims to provide reliable and just-in-time message delivery for a mobile sink node. To consider the mobile entity with the different moving speed, a new mobicast routing protocol is investigated in this work by utilizing the cluster-based approach. The message delivery of nodes in the forwarding zone of the HVE-mobicast routing protocol is transmitted by two phases; cluster-to-cluster and cluster-to-node phases. In the cluster-to-cluster phase, the cluster-head and relay nodes are distributively notified to wake them up. In the cluster-to-node phase, all member nodes are then notified to wake up by cluster-head nodes according to the estimated arrival time of the delivery zone. The key contribution of the HVE-mobicast routing protocol is that it is more power efficient than existing mobicast routing protocols, especially by considering different moving speeds and directions. Finally, simulation results illustrate performance enhancements in message overhead, power consumption, needlessly woken-up nodes, and successful woken-up ratio, compared to existing mobicast routing protocols.     

Message Drop Control Buffer Management Policy for DTN Routing Protocols

In delay tolerant network interruptions will occur continuously because there is no end-to-end path exists for the longer period of time from source to destination. In this context, delays can be immensely large due to its environment contrails e.g. wildlife tracking, sensor network, deep space and ocean networks. Furthermore, larger replication of messages put into the network is to increase delivery probability. Due to this high buffer occupancy storage space and replication result in a huge overhead on the network. Consequently, well-ordered intelligent message control buffer drop policies are necessary to operate on buffer that allows control on messages drop when the node buffers are near to overflow. In this paper, we propose an efficient buffer management policy which is called message drop control source relay (MDC-SR) for delay tolerant routing protocols. We also illustrate that conventional buffer management policy like Drop oldest, LIFO and MOFO be ineffective to consider all appropriate information in this framework. The proposed MDC-SR buffer policy controls the message drop while at the same time maximizes the delivery probability and buffer time average and reduces the message relay, drop and hop count in the reasonable amount. Using simulations support on an imitation mobility models Shortest Path Map Based Movement and Map Route Movements, we show that our drop buffer management MDC-SR with random message sizes performs better as compared to existing MOFO, LIFO and DOA.     

Optimal energy efficiency routing strategy based on community in mobile social network

An optimal energy efficiency routing strategy based on community was proposed,which minimized the network energy consumption under the given delay constraint.Firstly the expected energy consumption and delay of message delivery in the connected network were obtained through Markov chain.Then the comprehensive cost function for delivering message from source node to destination node was designed,which was combined with energy consumption and delay.Thus,the optimization function to comprehensive cost of relay node delivering message was obtained,and further the reward function of relay node was gotten.Finally the optimal expected reward of optimal relay node was achieved using the optimal stopping theory,so as to realize the optimal energy efficiency routing strategy.In simulations,the average energy consumption,the average delay and the average delivery ratio of routing optimization strategy were compared with those of other routing strategies in related literatures.The results show that the strategy proposed has smaller average energy consumption,shorter average delay and higher average delivery ratio,gaining better energy consumption optimization effect.     

Delay control in MANETs with erasure coding and f-cast relay

Packet delay control in mobile ad hoc networks (MANETs) is critical to support delay-sensitive applications in such networks. By combining erasure coding and packet redundancy techniques, this paper proposes a general two-hop relay algorithm 2HR- \((x,\tau ,f)\) for a flexible control of packet delivery delay in MANETs, where a group of x packets in source node are first encoded into \(x\cdot \tau\) encoded packets based erasure coding, and each encoded packet is then delivered to at most f distinct relay nodes (f-cast) that will help to forward the encoded packet to destination node. To understand the delay performance in a 2HR- \((x,\tau ,f)\) MANET, we then develop a discrete time multi-dimensional Markov chain model to depict the packet delivery process in the network, based on which closed-form results on mean and variance of packet delivery delay are further derived. Finally, extensive simulation and theoretical results are provided to illustrate the efficiency of our delay models as well as the capability of the 2HR- \((x,\tau ,f)\) algorithm in delay control.     

Trading latency for energy in densely deployed wireless ad hoc networks using message ferrying

Wireless mobile ad hoc networks (MANETs) have the potential for use in important application environments, such as remote environmental monitoring, where energy resources are limited. Efficient power management is necessary to allow these networks to operate over a long period of time. One of the key factors affecting the design of power management mechanisms is the routing protocol in use within the network. In this paper, we investigate the Message ferrying (MF) routing paradigm as a means to save energy while trading off data delivery delay. In MF, special nodes called ferries move around the deployment area to deliver messages for nodes. While this routing paradigm has been developed mainly to deliver messages in partitioned networks, here we explore its use in a connected MANET. The reliance on the movement of ferries to deliver messages increases the delivery delay if a network is not partitioned. However, delegating message delivery to ferries provides the opportunity for nodes to save energy by aggressively disabling their radios when ferries are far away. To exploit this feature, we present a power management framework, in which nodes switch their power management modes based on knowledge of ferry location. We evaluate the performance of our scheme using ns-2 simulations and compare it with a multihop routing protocol, dynamic source routing (DSR). Our simulation results show that MF achieves energy savings as high as 95% compared to DSR without power management and still delivers more than 98% of messages. In contrast, a power-managed DSR delivers many fewer messages than MF to achieve similar energy savings. In the scenario of heavy traffic load, the power-managed DSR delivers less than 20% of messages. MF also shows robust performance for highly mobile nodes, while the performance of DSR suffers significantly. Thus, delay tolerant applications can use MF rather than a multihop routing protocol to save energy efficiently when both routing approaches are available.     

Multi-Spreader Routing for sparsely populated mobile ad hoc networks

We propose Multi-Spreader Routing, a store-carry-forward routing scheme for sparsely populated mobile ad hoc networks. Multi-Spreader Routing includes Epidemic Routing and Two-Hop Forwarding as special cases, and it can manage trade-off between message delivery delay and resource consumption effectively. We analyze various performance measures of Multi-Spreader Routing with a recovery scheme called VACCINE, and we evaluate its performance. Further, through simulation experiments with real mobility trace data, we demonstrate that Multi-Spreader Routing shows stable performance in various network environments.     

Controlled flooding in disconnected sparse mobile networks

The incredible growth in the capabilities and functionality of mobile devices has enabled new applications and network architectures to emerge. Due to the potential for node mobility, along with significant node heterogeneity, characteristics such as very large delays, intermittent links, and high link error rates pose a new set of network challenges. Along with these challenges, end‐to‐end paths are assumed not to exist and message relay approaches are often adopted. While message flooding is a simple and robust solution for such cases, its cost in terms of network resource consumption is unaffordable. In this paper, we focus on the evaluation of different controlled message flooding schemes over disconnected sparse mobile networks. We study the effect of these schemes on message delay, network resource consumption, and neighbor discovery overhead. Our simulations show that our schemes can save substantial network resources while incurring a negligible increase in the message delivery delay. Copyright © 2008 John Wiley & Sons, Ltd.