Analysis on topology control boundary conditions in delay tolerant wireless sensor networks

In wireless sensor networks(WSNs),nodes are often scheduled to alternate between working mode and sleeping mode from energy efficiency point of view.When delay is tolerable,it is not necessary to preserve network connectivity during activity(working or sleeping) scheduling,enabling more sensors to be switched to sleeping mode and thus more energy savings.In this paper,the nodal behavior in such delay-tolerant WSNs(DT-WSNs) is modeled and analyzed.The maximum hop count with a routing path is derived in order not to violate a given sensor-to-sink delay constraint,along with extensive simulation results.

Fault Tolerant Synchronization for a General Complex DynamicalNetwork with Random Delay

A fault tolerant synchronization strategy is proposed to synchronize a complex network with random time delays and sensor faults. Random time delays over the network transmission are described by using Markov chains. Based on the Lyapunov stability theory and stochastic analysis, several passive fault tolerant synchronization criteria are derived,which can be described in the form of linear matrix inequalities. Finally,a numerical simulation example is carried out and the results show the validity of the proposed fault tolerant synchronization controller.

Offloading Mobile Data from Cellular Networks Through Peer-to-Peer WiFi Communication:A Subscribe-and-Send Architecture

Currently cellular networks do not have sufficient capacity to accommodate the exponential growth of mobile data requirements.Data can be delivered between mobile terminals through peer-to-peer WiFi communications(e.g.WiFi direct),but contacts between mobile terminals are frequently disrupted because of the user mobility.In this paper,we propose a Subscribe-and-Send architecture and an opportunistic forwarding protocol for it called HPRO.Under Subscribe-and-Send,a user subscribes contents on the Content Service Provider(CSP) but does not download the subscribed contents.Some users who have these contents deliver them to the subscribers through WiFi opportunistic peer-to-peer communications.Numerical simulations provide a robust evaluation of the forwarding performance and the traffic offloading performance of Subscribe-and-Send and HPRO.

OceanRoute: Vessel Mobility Data Processing and Analyzing Model Based on MapReduce

The network coverage is a big problem in ocean communication, and there is no low-cost solution in the short term. Based on the knowledge of Mobile Delay Tolerant Network(MDTN), the mobility of vessels can create the chances of end-to-end communication. The mobility pattern of vessel is one of the key metrics on ocean MDTN network. Because of the high cost, few experiments have focused on research of vessel mobility pattern for the moment. In this paper, we study the traces of more than 4000 fishing and freight vessels. Firstly, to solve the data noise and sparsity problem, we design two algorithms to filter the noise and complement the missing data based on the vessel's turning feature. Secondly, after studying the traces of vessels, we observe that the vessel's traces are confined by invisible boundary. Thirdly, through defining the distance between traces, we design MR-Similarity algorithm to find the mobility pattern of vessels. Finally, we realize our algorithm on cluster and evaluate the performance and accuracy. Our results can provide the guidelines on design of data routing protocols on ocean MDTN.

DTMSN中的分布式密钥更新模型

为了解决容延迟移动传感器网络中密钥更新过程中密钥分发延迟不确定的问题,保证分发过程中新密钥的安全性,提出了一种分布式密钥更新模型。该模型使用密钥分片机制,将新密钥分片预先置入网络中移动节点中,当密钥更新开始后,节点与网络内其他节点相遇后可获取自己的密钥片,多个密钥片组合后生成自己的新密钥。针对该模型的安全性和性能分析表明,通过对密钥分片数量的调整,该模型可以满足用户对分发过程中不同安全性要求和不同网络资源消耗要求。仿真结果表明该模型能够在不同网络参数变化的条件下对更新延迟做出比较准确的估计,解决了密钥分发延迟不确定的问题。

EMRPP:一种DTMSN组播路由算法

针对容迟移动传感器网络(Delay Tolerant Mobile Sensor Network,DTMSN)网络的容迟及节点的移动性特点,提出了一种新的基于概率预测的能量均衡组播路由算法(Energy-balanced Multicast Routing based Probability Probabilistic,EMRPP)。该算法采用到达概率选择路由下一跳的方式,且考虑了节点能量对算法性能的影响。仿真结果表明,EMRPP算法在数据传输率和平均传输延迟方面的性能要优于改进之前的PROPHET算法,是一种有效的容迟移动网络组播路由方案。

基于节点相遇时间估计的DTMSN路由算法

针对行人场景下节点相遇具有一定规律性的情况,提出了一种基于节点相遇时间估计的容延迟移动传感器网络路由算法(EEBR),以优化行人场景下的网络性能。通过对节点间历史相遇信息和节点间相互关系的分析,设计了一种实时估计普通节点和汇聚节点相遇概率的方法,并对发送缓冲区转发机制进行了设计。基于EEBR的行人场景数据集下的仿真结果表明,与传统的路由算法相比,EEBR算法的消息投递成功率、平均投递延迟和网络负载等关键指标更优。

基于博弈的DTMSN路由选择和信任决策

针对延时容忍移动传感器网络中节点自私性检测存在未考虑节点由于自身问题不能转发数据而引起信誉值计算不精确和重传数据造成能量浪费的问题,通过引入剩余能量和能否进行数据转发的两个概念,结合相应的惩罚机制,进一步提高了延时容忍移动传感器网络中节点自私性检查的准确度,同时可以延长网络的生存时间。对于现有延时容忍移动传感器网络中缺乏相应的激励机制,引入博弈的思想,通过理论证明,在条件允许的情况下节点会选择合作的行为,从而增加节点主动转发数据的积极性,提高网络的投递成功率,减少网络开销。

一种基于综合效用的DTMSN喷射转发路由算法

考虑到容迟移动传感器网络(DTMSN)的资源受限性,提出了一种基于综合效用的多副本喷射转发路由算法,通过计算综合效用值来指导消息副本在网络中的复制与转发.同时,为了减少冗余副本所带来的影响,还提出了一种与之相匹配的缓存管理机制.仿真结果表明,算法在有效性、可靠性和资源的使用等方面相比SWR算法均有不同程度的改善.

Performance Analysis of DEBT Routing Protocols for Pocket Switch Networks

Pocket Switched Networks(PSN)represent a particular remittent network for direct communication between the handheld mobile devices.Compared to traditional networks,there is no stable topology structure for PSN where the nodes observe the mobility model of human society.It is a kind of Delay Tolerant Networks(DTNs)that gives a description to circulate information among the network nodes by the way of taking the benefit of transferring nodes from one area to another.Considering its inception,there are several schemes for message routing in the infrastructure-less environment in which human mobility is only the best manner to exchange information.For routing messages,PSN uses different techniques such asDistributed Expectation-Based Spatio-Temporal(DEBT)Epidemic(DEBTE),DEBT Cluster(DEBTC),and DEBT Tree(DEBTT).Understanding on how the network environment is affected for these routing strategies are the main motivation of this research.In this paper,we have investigated the impact of network nodes,the message copies per transmission,and the overall carrying out of these routing protocols.ONE simulator was used to analyze those techniques on the basis of delivery,overhead,and latency.The result of this task demonstrates that for a particular simulation setting,DEBTE is the best PSN routing technique among all,against DEBTC and DEBTT.

基于节点紧密度中继转发的移动延迟容忍传感网传输算法

为解决移动延迟容忍传感网存在的时延突出、超宽带传输性能不佳等问题,提出了一种基于节点紧密度中继转发的移动延迟容忍传感网传输算法。引入邻域节点数量作为指标,以评估节点相遇概率,将节点相遇过程优化为邻域节点覆盖问题,以提升网络对节点相遇过程的感知能力。采用邻域节点重复覆盖数量作为判定依据,以评估节点运动性能,设计了基于紧密度的节点相遇感知机制,对节点运动活跃程度进行感知,增强节点对相遇过程的感知能力,有效提高下一跳目标节点的链接质量。基于马尔科夫评估机制,采用连接状态转移矩阵来评估节点链接概率,优选链接性能较高的节点作为下一跳节点,以优化源节点与目的节点间链路,增强链路对高带宽传输环境的适应能力。仿真结果表明,与基于分簇机制的传感网节能传输算法和基于低时延机制的传感网传输编码算法相比,所提算法具有更低的平均端对端时延和链路累计中断次数,以及更高的全网传输带宽。

基于信用度机制的移动延迟容忍传感网中继传输优化算法

为改善移动延迟容忍传感网(MD⁃TSN)的网络传输能力,提出了基于信用度机制的移动延迟容忍传感网传输优化算法。引入副本机制,设计了鉴权信息结构,将源节点与目的节点之间的链路连通程度及身份信息进行量化解析,以提升网络对中继链路的评估能力。采用双线性映射来构建注册鉴权密钥,以此设计了基于身份鉴权机制的中继节点可信度确认机制,通过结合哈希映射对中继节点进行身份鉴权,以降低中继节点的离线率,有效提高所选链路及中继节点的稳定性能。随后,基于信用分级评估模式,采取一级信用值、次级信用值筛选服务能力较强的中继节点作为备选节点,构建了基于信用度机制的节点激励方法,激励具有较强服务能力的节点,惩罚存在拒绝服务行为的中继节点,以进一步优化源节点与目的节点间链路,增强中继节点对源节点的服务覆盖能力。仿真实验表明,与当前常用的基于能量多跳路由机制的传感网传输算法和基于模糊-猫群优化机制的无线传感网多径传输算法相比,所提算法具有更高的网络传输带宽,以及更低的路径抖动频次和中继节点离线率。

Message redundancy removal of multi-copy routing in delay tolerant MANET

This article puts forward a new scheme to control message redundancy efficiently in delay tolerant mobile Ad-hoc networks （MANET）. The class of networks generally lacks end-to-end connectivity. In order to improve the efficiency that messages are delivered successfully, multiple message copies routing protocols are usually used, but the network load is increased due to a large number of message redundancies. In the study, by using counter method, every node adds an encounter counter based on epidemic routing scheme. The counter records the number which the node encounters other nodes with the same message copy. If the counter of a node reaches tbe installed threshold, the node removes the copy. Theoretical analysis gives a lower bound of threshold in delay tolerant MANET. According to the lower bound of threshold, a rational threshold is installed in real environment. With proposed scheme message copies decrease obviously and are removed completely finally. The successful delivery efficiency is still the same as epidemic routing and the redundant copies are efficiently controlled to a relatively low level Computer simulations give the variation of message copies concerning different thresholds in fast and slow mobility scenes.

延迟容忍移动传感器网络中基于选择复制的数据传输

提出了一种基于选择复制的动态数据传输策略SRAD(selective replication-based adaptive data delivery scheme),基本思想是把消息(message)动态的复制给更有可能与汇聚点(sink node)通信的传感器节点.SRAD由数据传输和队列管理两个主要部分组成:前者根据Random Waypoint随机运动模型下不同时刻各传感器节点传输概率的大小进行数据消息的传输;后者通过消息的生存时间ST(survival time)值决定队列中消息传递的优先顺序和丢弃原则,以进一步降低网络传输能耗.模拟实验结果表明,与现有的几种DTMSN(delay tolerant mobile sensor networks)数据传输算法相比,SRAD的网络寿命相对较长,且它能以较低的数据传输能耗和传输延迟获得较高的数据传输成功率.

延迟容忍传感器网络基于相对距离的数据传输

延迟容忍移动无线传感器网络(delay tolerant mobile sensor network,简称DTMSN)用于广泛数据收集.与传统的传感器网络不同,DTMSN具有节点移动性、间歇连通性并且能够容忍适当的延迟,因此传统传感器网络的数据收集算法不能适用.提出了一种基于相对距离感知的动态数据传输策略RDAD(relative distance-aware data delivery scheme).RDAD采用传感器节点到汇聚点(sinknode)的相对距离来计算节点传输概率的大小,并以此作为消息(message)传输时选择下一跳的依据.为优化复本管理,RDAD引入消息的生存时间ST(survival time)和消息最大复制数MR(maximal replication)决定队列中消息传递的优先顺序和丢弃原则.模拟实验表明,与现有的几种DTMSN数据传输算法相比,RDAD能够以较低的数据传输能耗和传输延迟获得较高的数据传输成功率,并且具有相对较长的网络寿命.

基于网络编码的延迟容忍移动传感器网络低时延广播传输机制

针对延迟容忍移动传感器网络(Delay Tolerant Mobile Sensor Networks,DTMSN)提出一种基于网络编码的广播传输机制(Netcoding-based Broadcast Transmission scheme,NBT)。NBT中,基站(Base Station,BS)将原始数据分批进行传输,每个批次包含的原始数据包的数量一定;BS将同一批次数据包以单播方式传输给不同传感器节点时采用的编码向量互不相关,传感器节点之间采用泛洪的机制交换彼此缺少的编码数据包。由于BS对原始数据包进行了编码,因此传感器节点具有相同编码数据包的可能性大大降低,从而减小了节点间的数据相关度,有效降低了广播时延。在随机路点移动模型(Random WayPoint,RWP)下的仿真结果表明,与目前广播时延最小的泛洪机制相比,NBT能够在通信开销基本相同的情况下有效降低广播传输时延。

延迟容忍传感器网络中基于群组运动的事件传输

提出了一种基于分布式群组移动的事件分类传输策略GMED(distributed group mobility adaptive event delivery).通过有效地发现和利用传感器节点在运动过程中形成的群组,建立基于群组的事件分类传输模型,改善数据传输性能.其中,群组的转发是依据各自与汇聚点的机会概率按照多副本方式进行的;而群内的事件传输则是基于各成员的稳定邻居集建立传输路径,并以单副本方式进行.队列管理则根据事件的优先级决定递交的顺序和丢弃原则.此外,引入冗余副本控制机制,优化副本管理,降低网络负载.模拟实验结果表明,与现有的几种DTMSN(delay tolerant mobile sensor networks)数据传输算法相比,GMED能以较低的数据传输能耗和传输延迟获得较高的数据传输成功率,且网络寿命相对较长.

异构延迟容忍移动传感器网络中基于转发概率的数据传输

提出了一种基于转发概率的动态数据转发策略:FPAD(forwarding probability-based adaptive data deliveryalgorithm).FPAD适用于由不同类型传感器节点构成的可监测不同对象的异构延迟容忍移动传感器网络HDTMSN(heterogeneous delay tolerant mobile sensor network).在这种网络中,各类节点拥有不同的通信能力、运动速度与消息存储能力,并且获取的数据消息具有不同的大小和不同的延迟容忍度.针对异构网络的特点,FPAD一方面根据节点能量消耗和消息传输延迟计算出节点的传输概率和转发概率,并以此进行数据消息的传输;另一方面,提出根据消息当前的延迟容忍度作为消息丢弃依据的消息队列管理机制.仿真实验结果表明,与现有的几种数据传输算法相比,FPAD的数据传输成功率更高、传输延迟更小,而且网络寿命相对较长.

基于运动状态的延迟容忍移动传感器网络数据传输策略

针对延迟容忍移动传感器网络(DTMSN,delay tolerant mobile sensor networks)提出一种基于节点运动状态的数据传输(MSD,motion state-based delivery)策略。MSD使用2个通信频率,传感器节点利用基站在频率f1上的广播信号完成自身运动状态和传输概率的计算,并以此作为利用频率f2进行消息转发的依据。为了提高性能,MSD中利用消息生存时间和自身消息优先传输机制来完成消息队列的管理。仿真结果表明,与现有的几种DTMSN数据传输策略相比,MSD能够以较低的通信开销和传输延迟达到较高的数据传输成功率。