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.     

DTN中基于时间因素的拥塞感知路由算法

为了解决散发等待路由算法中,中继节点的选择存在盲目性的问题,提出一种基于时间因素的拥塞感知路由算法CARA。该算法考虑时间因素对转发概率的影响,改进Prophet算法中的转发概率。根据改进的转发概率选择中继节点,动态分配报文转发数目,并以拥塞感知自适应的方式实现拥塞控制的优化。仿真结果表明,CARA算法和网络投递率及延迟表现最好的CS-DTN算法相比,投递率提高了10.21%,延迟降低了7.05%,同网络开销表现最好的BSW算法相比,开销降低了8.16%。     

一种基于旁听的机会网络路由算法

针对基于议价博弈的概率路由算法存在消息传送成功率提升偏慢、开销大、节点无序情况下竞争信道引起碰撞以及节点在多邻居状态下存在冗余交互的问题,提出一种基于旁听的机会网络路由算法—ORON。ORON算法通过旁听邻居节点信息,设计博弈策略使激励相容,节点对邻居与自身的交易状态进行分析,选择最佳策略,使得网络性能得到提升。仿真验证了ORON算法设计的有效性,结果表明：与基于议价博弈的现有路由算法GSCP相比,ORON算法的吞吐量和消息传送成功率至少提高了6.72%,而控制开销和平均端到端消息时延则分别降低了20%和3.55%以上。     

基于预期移动行为的校园机会网络路由机制

针对校园机会网络较少考虑节点未来移动行为的问题,提出基于预期移动行为的路由机制。基于人类动力学知识预测节点访问各兴趣域时间长度并归一化处理,利用时间比度量节点访问对应兴趣域的概率,以向量形式描述节点预期移动行为;基于最优节点选择算法,将消息投递到与目的节点预期移动行为相似度高的中继节点,直到目的节点。实例仿真计算结果表明,该路由机制在节点密度大、缓存受限条件的校园机会网络中可以提高路由性能,降低网络开销。     

基于位置信息的改进AODV路由算法

针对AODV协议路由开销较大的问题,提出一种基于位置信息的改进路由协议(GAODV).GAODV利用中间节点重新计算转发角度,保证转发角度内邻居节点数不小于预设门限值,同时还引入基于位置信息的计数器方案,使距离目的节点近的中间节点优先转发路由请求消息,有利于减少转发冗余路由请求信息和降低寻路失败概率.OPNET仿真实验结果表明,GAODV在数据分组投递率、路由开销、总丢包数、端到端时延和平均路由跳数等方面都优于已有算法.     

基于历史效用的机会网络路由算法

针对机会网络中传统的概率路由协议投递率较低的问题,提出一种基于历史相遇预测的改进概率路由(HMPR)算法。该算法根据节点历史接触时间和接触频率两个因素,预测数据包成功投递到目的节点的效用值,通过比较其效用值大小来决定数据包是否转发到下一跳节点。仿真结果表明,与传统的传染路由和概率路由相比,该路由在数据包投递率、平均延迟时间和平均缓存时间方面比上述两个路由协议的性能更好。     

延迟容忍网络中基于概率传递的可靠路由算法

针对延迟容忍网络中节点缓存受限引起大量消息被丢弃的问题,在概率路由算法的基础上,提出一种基于概率传递的可靠路由算法R PROPHET。该路由算法根据节点缓存中消息替换的历史情况评价节点的可靠性,以保证消息在可靠的节点间传输直至交付给目的节点。仿真结果表明,该算法能够减轻消息在节点间无效传递的情况,能够获得较高的消息交付率,并具有较低的通信开销。     

移动社会网络中基于社区的消息机会传输策略

移动社会网络是一种由大量具有社会特征的节点组成的机会网络.已有的基于社区的路由算法大多选用社会性最优的节点参与转发,而没有考虑到社区分布对节点移动的影响,将这些算法直接用于移动社会网络中会导致网络资源消耗高、传输成功率低等问题.针对这些问题,提出一种基于社区的消息机会传输算法,在社区间根据节点到目标社区的传输概率选择社区间的最优传输路径,在社区内选择与目标节点相遇概率较高的节点完成社区内传输.仿真实验结果表明,在移动社会网络中,该算法与 Prophet,Spray and Wait 等经典算法相比,提高了消息传输成功率,降低了网络开销.     

基于马尔可夫决策过程的机会网络转发策略

在机会网络节点随机移动的场景中,提高路由算法性能评价中的投递率,控制开销率,降低平均迟延是持续的研究方向。由于目前机会网络结构稀疏和拓扑多变,单副本路由转发策略效率较低。通过结合花粉布朗运动与机会网络节点的随机运动的相似性,并分析节点随机运动的规律,定义了一种基于马尔可夫决策过程的节点转发策略。该策略在平均延时适当增加的情况下,可以有效控制网络开销率,提高消息投递率。最后通过仿真实验验证了理论模型的正确性。     

ILAR：移动自组网中路由算法LAR协议的改进

选取一种典型的基于地理位置信息的路由协议--LAR协议进行深入的研究,并针对LAR协议的不足提出一种改进路由协议--ILAR协议.在建立路由的过程中,ILAR综合考虑了到目的节点的距离与链路保持时间这两个参数,在邻居表中选择有限个节点作为转发节点,不仅减少了控制开销,同时提高了数据传输的成功率.此外,ILAR在找不到路由时,通过局部泛洪来重新寻找路由,避免了全网泛洪,进一步减少了网络中的控制开销.模拟结果表明,该路由算法在分组投递率以及控制开销等方面都有较大的改善,减少了网络拓扑结构的变化对路由的影响,极大地提高了网络性能.     

A Buffer Scheduling Method Based on Message Priority in Delay Tolerant Networks

Routing protocols in delay tolerant networks usually utilize multiple message copies to guarantee the message delivery, in order to overcome unpredictable node mobility and easily-interrupted connections. A store-carry-and-forward paradigm was also proposed to further improve the message delivery. However, excessive message copies lead to the shortage of buffer and bandwidth. The spray and wait routing protocol has been proposed to reduce the network overload caused by the buffer and transmission of unrestricted message copies. However, when a node’s buffer is quite constrained, there still exist congestion problems. In this paper, we propose a message scheduling and drop strategy on spray and wait routing protocol (SDSRP). To improve the delivery ratio, first of all, SDSRP calculates the priority of each message by evaluating the impact of both replicating and dropping a message copy on delivery ratio. Subsequently, scheduling and drop decisions are made according to the priority. In order to further increase delivery ratio, we propose an improved message scheduling and drop strategy on spray and wait routing protocol (ISDSRP) through enhancing the accuracy of estimating parameters. Finally, we conduct extensive simulations based on synthetic and real traces in ONE. The results show that compared with other buffer management strategies, ISDSRP and SDSRP achieve higher delivery ratio, similar average hopcounts, and lower overhead ratio.     

Spray and forward:Efficient routing based on the Markov location prediction model for DTNs

Typical delay tolerant networks(DTNs)often suffer from long and variable delays,frequent connectivity disruptions,and high bit error rates.In DTNs,the design of an efficient routing algorithm is one of the key issues.The existing methods improve the accessibility probability of the data transmission by transmitting many copies of the packet to the network,but they may cause a high network overhead.To address the tradeoff between a successful delivery ratio and the network overhead,we propose a DTN routing algorithm based on the Markov location prediction model,called the spray and forward routing algorithm(SFR).Based on historical information of the nodes,the algorithm uses the second-order Markov forecasting mechanism to predict the location of the destination node,and then forwards the data by greedy routing,which reduces the copies of packets by spraying the packets in a particular direction.In contrast to a fixed mode where a successful-delivery ratio and routing overhead are contradictory,a hybrid strategy with multi-copy forwarding is able to reduce the copies of the packets efficiently and at the same time maintain an acceptable successful-delivery ratio.The simulation results show that the proposed SFR is efficient enough to provide better network performance than the spray and wait routing algorithm,in scenarios with sparse node density and fast mobility of the nodes.     

一种多用户协作博弈的视频机会传输路由算法

移动用户间日益普及的视频数据传输,使得传统无线通信网络上的流量爆炸性增长问题变得愈发严重,而基于D2D通信的数据机会传输被认为是能够实现数据卸载的有效方法.然而在移动机会网络中,数据传输主要通过数据复制和机会转发而实现.为了获得较高的投递率和较低的投递时延,数据复制往往被过度使用,冗余的数据包不仅会消耗大量的设备和网络资源,还会增加网络的传输负载,降低网络性能.对于视频数据传输,由于其较强的持续性和远高于一般标量数据的数据量,该问题会更加突出.因此,基于多人协作博弈,提出了一种面向视频传输质量的机会路由算法VOR-MG,实现对视频传输质量和传输开销的优化.具体来讲,首先建立视频数据包的边缘质量增益模型,然后把多用户相遇时的视频数据传输建模为一个多用户协作博弈,最后,基于其纳什最优解来对每个视频数据包的复制或者转发进行决策,从而保证在视频传输质量最优的情况下,使得网络中的视频数据包备份个数最少.基于合成数据集和真实数据集的仿真结果表明：其视频传输质量比对比算法高出1 dB~2dB,但是平均最大数据包备份数仅为同类算法的25%左右.     

带路径收集的移动自组网AODV协议优化

研究并提出了一种带路径收集机制的AODV协议优化方案，有效地结合了DSR协议的路径收集思想，在提高AODV协议运行效率的同时不会引入DSR协议运行开销大、可扩展性差等局限。经NS模拟后的性能分析比较，优化的AODV协议在提高分组发送成功率、降低路由开销、缩短端端延迟等方面效果显著。     

An adaptive and opportunistic broadcast protocol for vehicular ad hoc networks

A primary goal of broadcasting in vehicular ad hoc network (VANET) is to improve the road safety by transmitting alert messages to all surrounding vehicles as soon as possible. In this paper, we adopt the concept of opportunistic routing and propose a multiple candidate relays opportunistic broadcast (MCROB) protocol for VANET. The MCROB protocol is a sender-driven broadcast scheme independent of node density. The packet delivery ratio (PDR) is derived and an expected transmission speed (ETS) for the MCROB is proposed. A priority rule for selecting a proper candidate relay and an adaptive algorithm for forwarding timers of candidate relays are also presented in this paper. Simulations show that MCROB is adaptive to the rapid changing of network conditions. It keeps a low communication overhead introduced by the broadcast and increases the average transmission speed by around 40%.     

片上网络中面向报文有序传输的自适应路由算法研究

与确定性路由算法相比,自适应路由算法可以提高片上网络的通信性能,但是报文可能会无序到达。在目的节点对报文排序将会导致严重的面积和计算开销,甚至可能会抵消采用自适应路由算法带来的性能增益。为此,本文首先提出一种部分自适应路由算法,以满足报文的有序到达。然后,描述了对本文算法提供支持的路由器硬件结构。最后,在二维片上网络下对本文算法及确定性和自适应路由算法进行了性能评估和比较。与XY算法相比,本文算法显著降低了报文延时,提升了饱和点。同时讨论了对路由器面积和功耗影响。虽然路由器的功耗有所上升,但是由于报文交付性能提升,因此每个flit的能耗增长可忽略不计。     

节点密度感知的容迟网络路由协议*

为适应容迟网络的动态变化,提高路由性能,结合空间节点分布和节点度中心性,提出一种节点密度感知的容迟网络路由协议DAR。该协议引入移动模型的节点分布,通过感知节点当前所处位置的节点密度,动态选择在网络中传播的消息副本数量,并根据节点的度中心性选择中继和分配消息副本数量。仿真结果表明,DAR能够提高传输率、降低传输延迟,在一定程度上降低了资源消耗。     

Potential based routing as a secondary best-effort routing for Information Centric Networking (ICN)

One challenge to the retrieval process of ICN is to take advantage of largely distributed copies in in-network caches. This paper proposes Potential Based Routing (PBR) as a secondary best-effort routing mechanism to boost availability of copies in ICN architectures. The control overhead issue of the PBR is evaluated through both theoretical analysis and numerical simulation. In addition, the paper provides the PBR with a recovery mechanism from a failure, which can reduce the control overhead traffic by at least 40% in the simulation environment. Lastly, it is demonstrated how an ICN architecture can benefit from this PBR in terms of cache hit and delay reduction ratios.     

A hybrid multiple copy routing algorithm in space delay-tolerant networks

With the development of technology and applications in space delay-tolerant networks (SDTNs), increasing attention has been paid on the routing technologies between different DTN nodes. This paper proposes a novel hybrid multiple copy routing (HMCR) algorithm that can be applied not only to deterministic space scenarios but also to opportunistic space scenarios. HMCR combines contact graph and delivery probability metrics to make forwarding decisions. In order to verify the new HMCR algorithm’s performance, research work has been carried out to prove its availability in SDTNs. The analysis and simulation results show that, compared with other algorithms such as contact graph routing (CGR), Epidemic, and PRoPHET, the new HMCR algorithm performs well in the areas of message delivery ratios, average end-to-end delays, and transmission overhead, which proves to be suitable for highly dynamic SDTNs.     

DTN中基于节点质量的自适应散发和等待路由

针对节点活动性的差异,给出了节点质量的定义,提出了基于节点质量的自适应散发和等待路由协议。该协议通过引入节点质量的观点来动态地转发报文拷贝数,从而避免了二分散发和等待路由协议在转发报文拷贝数时的盲目性。仿真结果显示,该协议更能够适应自组织状况下动态的网络拓扑,在改善报文递交率和延迟的同时能显著提高报文的递交效用、减小网络开销率。