基于社会组的高投递率机会网络路由协议

针对现有的基于社会组的机会网络路由协议（SGBR）存在中继节点的选择和消息副本数量的分配不合理的问题,提出了基于社会组的高投递率机会网络路由协议（SGBRHDR）。SGBRHDR协议是一种采用分布式划分社会组的多副本路由协议。在社会组内,节点依据平均关系强度值决定相遇节点是否成为转发节点;在社会组间,节点依据相遇节点所在的社会组活跃性大小分配消息副本数量。采用ONE工具对SGBRHDR协议进行了仿真,仿真结果表明：与SGBR协议相比,SGBRHDR协议减小了消息平均端到端时延的同时,消息投递成功率提高了18%。     

基于节点运动预测的社会性DTN高效路由

延迟容忍网络是一种缺乏持续连接的新型网络体系结构,采用存储-携带-转发的路由方式进行消息的转发.考虑到节点的特性及运动模式,基于分簇、社会网络的路由协议已成为近年来的一个研究热点.该文分析现有基于分簇、社会网络的路由算法的缺陷及社会网络的特点,提出了一种新型的混合路由算法CS-DTN(Clustering&Social Delay Tolerant Network):预测节点间的相遇概率并据此对节点进行分簇,簇内根据节点间相遇概率限定消息的副本数量,将消息以二分喷射的方式转发到更可能到达目的节点的中继节点;簇间对节点进行运动预测并结合节点的特性将消息不断地转发到更接近目的节点的中继节点.不同于已有的基于分簇、社会网络的路由算法,CS-DTN从多个角度结合了节点自身及节点间的特性,更考虑了对节点的运动预测,降低了由不必要的消息转发带来的资源浪费,同时也能更高效地将消息投递到目的节点.仿真结果表明CS-DTN较为明显地提升了消息的成功投递率并降低了消息的平均端到端延迟,在缓存足够的前提下,CS-DTN可以实现高达95%的投递率,而在资源有限的情况下也能获得80%以上的投递率.     

一种基于历史相遇信息的容迟网络地理路由算法

为使消息在容迟网络中更有效地传输,将节点的地理位置、移动方向等地理信息与节点间的历史相遇频繁程度相结合,提出一种新的容迟网络地理路由算法。该算法将移动节点间的历史相遇信息作为分配消息副本的依据,从而减少复制策略路由算法中的副本数量。利用邻居节点移动方向所构成的夹角对中继节点的选择进一步优化,得到较高的投递率以及较低的端到端平均时延。仿真结果表明,当节点移动相对缓慢并且消息生存周期较短时,该算法的消息投递率优于Spray&Wait,Epidemic,Prophet等路由算法,在消息生存周期较短的情况下,当节点的缓存资源为限制路由算法性能的瓶颈因素时,与Epidemic算法相比,网络负载率降低40%,与Prophet算法相比负载降低了25%,有效减少了平均跳数和平均时延。     

社会感知多副本车载自组织网络机会路由协议

为提高车载自组织网络(vehicular Ad hoc networks, VANETs)中消息投递的效率, 提出了一种社会感知多副本车载自组织网络机会路由协议(SAMOR)。协议结合了车载自组织网络中节点的社会性特点和多副本路由方案的优势, 采用携带—存储—转发的机会路由方式进行消息投递。利用节点间的相遇历史区分社区节点和全局节点, 并使用所提出的节点社区中心性和网络中心性的度量方法, 得到了节点的效用。在路由过程的扩散阶段, 节点间按效用分配副本, 在转发阶段, 副本继续向效用高的节点转发。仿真结果表明, SAMOR实现了较高的消息投递成功率和较低的延迟。     

车载传感网中基于群特性的MaxProp路由协议改进

车载传感网中信息传输面临的主要难题是网络间歇性连通和拓扑高度动态变化,以往常常采用机会转发的思想设计路由协议来解决此难题。但现有的机会路由协议忽略了网络中部分车辆节点具有群组移动的特点,从而导致协议在群组移动场景下的性能急剧下降。为此,通过对最大相遇概率路由进行改进,提出了一种基于群特性的MaxProp路由协议。该协议利用群组内成员节点之间极好的连通性,通过群内消息扩散,间接提高群内节点与群外节点之间的相遇概率,从而增加了消息转发机会。并在ONE仿真平台上,与其他几种经典的机会路由协议相对比,改进后的MaxProp路由协议在消息传输成功率、网络开销比方面具有明显提升。     

基于历史与位置信息的容迟网络路由算法

针对容迟网络消息投递率低、网络时延高的问题,提出一种基于节点历史相遇信息和位置信息选取下一跳路由节点的算法。利用节点间历史相遇信息,筛选出与目的节点相遇次数最多的节点进行消息复制,并进一步采用节点位置信息计算邻居节点的移动方向,得到移动方向夹角较大的一对节点进行消息复制。仿真结果表明,在消息生命周期较短且节点缓存空间不充裕的情况下,与遇到节点即复制消息的传染病算法相比,该算法平均时延降低50%,且具有较高的消息投递率。     

容迟容断网络路由协议研究

容迟容断网络近年来得到了广泛的研究和应用.容迟容断网络中源节点和目的节点之间不存在持续稳定的端到端路径,因而传统网络的路由协议无法适用于容迟容断网络.为了完成容迟容断网络消息传输,采用基于存储-转发的路由机制.容迟容断网络路由协议性能受链路生存时间、节点缓存大小以及网络中节点移动模型等影响.对容迟容断网络路由协议的研究和进展进行了较为深入的探讨,对主要路由协议的性能进行了比较,并总结了未来的研究方向.     

基于路由长度的多径路由协议

针对单径路由协议在高速Ad hoc网络中平均端到端时延和丢包率高的问题,在动态源路由协议的基础上,提出基于邻居节点变化率与路由长度的多径路由协议DSR_HD。利用HELLO消息获得一跳范围内可用邻居数,根据邻居数求得节点的邻居节点变化率。在路由发现过程中,采用路由距离与路由跳数相结合的方法计算路由长度,并选择邻居节点变化率和路由长度低的节点加入路由,从而提高路由的稳定性。仿真实验结果显示,DSR_HD协议可以有效减少数据分组传输的端到端时延及路由开销,提高分组成功投递率。     

容迟网络中传染路由协议优化

针对传染路由协议（EPI）的泛洪机制会造成容迟网络资源浪费的问题,提出将节点间的历史相遇信息引入传染路由协议的改进算法（EPI-HT）,以达到准确选择数据下一跳转发节点的目的。仿真结果表明,改进后的EPI-HT比EPI明显抑制了数据泛洪传输,可提高交付率,同时降低端到端时延。     

基于节点稳定性与跨层优化的MANET路由设计

针对移动自组织网络(MANET)中优化链路状态路由(OLSR)协议路由稳定性差和端到端延时高的问题,提出一种改进的OLSR路由协议。考虑MANET拓扑的移动性,通过优先选择平均相遇率较小、稳定性较高的中继节点构建移动拓扑,避免路由震荡。基于跨层技术,利用链路层共享的链路速率优化路由权值,从而提高路由性能。实验结果表明,与OLSR协议相比,改进协议在MANET网络中具有更好的网络稳定性及更低的端到端延时。     

Depth-first search approach for fault-tolerant routing in hypercubemulticomputers

Using depth-first search, the authors develop and analyze the performance of a routing scheme for hypercube multicomputers in the presence of an arbitrary number of faulty components. They derive an exact expression for the probability of routing messages by way of optimal paths (of length equal to the Hamming distance between the corresponding pair of nodes) from the source node to an obstructed node. The obstructed node is defined as the first node encountered by the message that finds no optimal path to the destination node. It is noted that the probability of routing messages over an optimal path between any two nodes is a special case of the present results and can be obtained by replacing the obstructed node with the destination node. Numerical examples are given to illustrate the results, and they show that, in the presence of component failures, depth-first search routing can route a message to its destination by means of an optimal path with a very high probability     

机会社会网络中基于社区的消息传输算法

针对机会网络中的主流转发协议未考虑到节点移动社会性的问题,提出一种基于副本限制和人类社会特性的路由算法。该算法根据节点间的社会关系强度,动态自适应地将节点划分为不同的社区,通过限制消息副本数来减少网络中消息的冗余,并利用活跃性高的节点带动消息的转发和传递。仿真结果表明,该协议能够保证较高的消息传输成功率和相对较低的传输时延,降低网络的资源消耗。     

AODV‐RIP: improved security in mobile ad hoc networks through route investigation procedure

Most routing protocols in mobile ad hoc networks (MANETs) place an emphasis on finding paths in dynamic networks without considering security. As a result, there are a number of attacks that can be used to manipulate the routing in MANET. A malicious node that sends a modified control message to an intermediate node can disturb the network using a control message. To solve this problem, we introduce AODV protocol with route investigation procedure (AODV‐RIP). It uses two additional control messages to defeat security attacks that can occur in AODV routing protocol. When an intermediate node that is on the path between the source node and the destination node receives a control message, it sends a Rroute Investigation Request (IREQ) message to the destination node in order to check the reliability of the control message. According to the existence of Route Investigation Reply (IREP), the intermediate node decides whether it transmits the control message to the source node or not. Consequently, the intermediate node that receives the control message confirms that it is using two additive control messages: IREQ and IREP. Through this investigation procedure, the source node can obtain a reliable path for transmitting data packets to an intentional destination node. The simulation results show an improvement in the packet delivery ratio and end‐to‐end delay at the expense of a moderate increase of the control message overhead compared with the current routing protocols. Copyright © 2009 John Wiley & Sons, Ltd.     

一种满足剩余能量约束的方向性Ad Hoc网络路由协议

本文提出一种基于剩余能量约束的方向性路由协议ED-AODV。该协议首先控制RREQ分组进行方向性传输来减小网络的洪泛负担;其次,提出基于剩余能量的预警机制,当移动节点剩余能量低于报警阈值时,通知源节点提前主动进行路由选择来提高路由的稳定性。ED-AODV采用的方向性控制RREO分组转发的方法又消除了提前进行路由选择带来的洪泛负担。仿真实验结果表明,在能量有限的情况下,采用ED-AODV协议在平均端到端时延、分组投递率性能指标上均优于AODV协议。     

基于信任机制的机会网络安全路由决策方法

提出一种基于信任机制的机会网络安全路由决策方法TOR,该方法在节点中引入信任向量的数据结构,记录节点携带消息能力的信任度.采用层状硬币模型和数字签名机制,在消息传递过程中将节点签名的转发证据动态捆绑到消息包上,依靠消息携带方式实现证据链的采集.周期性地将具有签名和时间戳的信任向量表通过洪泛方式反馈到网络中,在每个节点,迭代形成一个由多维行向量集组成的只读可信路由表TRT,作为选择下一跳节点和副本分割策略的决策依据.在节点相遇时,选择信任度比自身大的作为下一跳转发节点,消息沿着信任梯度递增的方向传递.实验结果表明：与现有路由算法相比,TOR算法能够有效抑制恶意节点和自私节点的破坏行为,且具有较高的消息传递成功率和较低的消息转发平均时延,对缓存空间和计算能力要求较低.     

求解带时延约束组播路由问题的启发式遗传算法

组播是一点到多点的信息传送方式。在视频会议等实时性要求较高的组播应用中，保证信息的传输时延尽可能小非常重要。有时延约束的组播路由问题已被证明是NP－Complete问题。研究带时延约束的组播路由问题，给出了一种遗传算法以求解该问题，算法采用了适合问题特点的遗传算子，能够较好地解决时延受限组播路由问题。     

Energy Based Random Repeat Trust Computation in Delay Tolerant Network

As the use of mobile devices continues to rise, trust administration will significantly improve security in routing the guaranteed quality of service (QoS) supply in Mobile Ad Hoc Networks (MANET) due to the mobility of the nodes. There is no continuance of network communication between nodes in a delay-tolerant network (DTN). DTN is designed to complete recurring connections between nodes. This approach proposes a dynamic source routing protocol (DSR) based on a feed-forward neural network (FFNN) and energy-based random repetition trust calculation in DTN. If another node is looking for a node that swerved off of its path in this situation, routing will fail since it won’t recognize it. However, in the suggested strategy, nodes do not stray from their pathways for routing. It is only likely that the message will reach the destination node if the nodes encounter their destination or an appropriate transitional node on their default mobility route, based on their pattern of mobility. The EBRRTC-DTN algorithm (Energy based random repeat trust computation) is based on the time that has passed since nodes last encountered the destination node. Compared to other existing techniques, simulation results show that this process makes the best decision and expertly determines the best and most appropriate route to send messages to the destination node, which improves routing performance, increases the number of delivered messages, and decreases delivery delay. Therefore, the suggested method is better at providing better QoS (Quality of Service) and increasing network lifetime, tolerating network system latency.     

Look-Ahead Routing and Message Scheduling in Delay-Tolerant Networks

Routing is one of the most challenging development issues in Delay-Tolerant Networks (DTNs) because of lack of continuous connection. Existing routing schemes for DTNs provide best effort service, but are unable to optimize QoS and support message priority. In this paper, we present a Look-Ahead Routing and Message Scheduling approach (ALARMS) which exploits more accurate knowledge about various parameters regarding routing to achieve better QoS in the DTN. We assume a variation of the well-known ferry model, in which there are ferry nodes moving along pre-defined routes to exchange messages with the gateway node of each region on the route and also pass to the gateway nodes look-ahead routing information about when it will arrive at each gateway node on the route in the next two rounds and how long it will stay. The gateway nodes use this information to estimate the delivery delay of each message when being delivered by different ferries, and schedule the message to be delivered by the ferry which arrives earliest at the destination. Simulation results show that ALARMS outperforms three existing routing protocols: epidemic routing, Spray-and-Wait, and Spray-and-Focus, in terms of delay time, delivery ratio, and overhead. We also discuss five enhancement strategies on ALARMS and how ALARMS can support message prioritization.     

Turn Grouping for Multicast in Wormhole-Routed Mesh Networks Supporting the Turn Model

Multicast is an important collective communication in scalable parallel computers. One efficient scheme to perform multicast is multidestination messaging[8]. In multidestination messaging, destination nodes of a multicast are partitioned into disjoint groups. Nodes in each group are reached with a multidestination message that conforms to the base routing algorithm of the system. A systematic way of partitioning the nodes is critical to the efficiency of multidestination messaging. In this paper we propose a node grouping method, called turn grouping, for partitioning the destination nodes in a multicast. Turn grouping is general in the sense that it supports any base routing algorithm derivable from the turn model [5]. Given such a base routing algorithm and the corresponding prohibited turns, turn grouping can systematically produce a proper schedule for multicasting the message. We evaluated the performance of turn grouping using three typical turn model-based routing algorithms. The simulation results show that our approach performs better than the Umesh [12] and the Hamiltonian-path [8] algorithms.     

移动社会网络中基于活动的消息机会转发

针对移动社会网络中节点移动形成的成簇特性和节点参与活动表现的周期特点,提出了一种基于活动的消息机会转发算法（activity-based message opportunistic forwarding,简称AMOF）.算法思想是：当消息携带节点与目的节点存在相同活动时,选择消息交付概率高的中继节点转发消息;当消息携带节点与目的节点不存在相同活动时,选择消息间接交付概率高的链路来转发消息.仿真结果表明,与经典路由算法（如Epidemic,PRoPHET,CMOT和CMTS）比较,所提出的路由算法不仅能够提高消息的传输成功率,还能有效地降低传输时延和网络负载.