基于马氏链的网络节点重要性评价方法

针对网络攻击与防御中资源分配时需对网络节点进行重要性评估的问题,提出了基于网络拓扑图的马氏链模型。并指出若网络中存在经过奇数次跳转能够回到自己的节点时,此网络图的马氏链就是遍历的,且其极限概率为该节点的度比上所有节点度之和。然后根据上述模型,提出把其它节点以最短路径到达该节点概率之和作为节点重要性评判指标。最后进行了实验分析,实验证实了所建模型的正确性,以及节点重要性评价算法的准确性。     

一种无标度网络上的局部路由策略

提出了一种无标度（scale-free）网络上的局部路由策略。每个节点根据其当前负载与自身发送能力（设为等于节点度）的关系,自适应调整其接收邻居节点信息包的概率。此概率与每个节点度的α次方成正比,α是可自适应变化的偏好因子,由节点度以及负载联合决定。当节点负载小于发送能力时,增大其偏好因子;反之,则减小。这样使得整个网络业务量较小时,可以优先把业务转发往度较大的节点,从而更快到达目的地;而业务量较大时,度大以及度小节点的发送能力均能得到充分利用,从而提高了整个网络的业务承载能力。仿真结果表明,该策略有效地提高了网络容量,并且降低了网络中信息包的平均传输时延。     

基于捕获效应的传感器网络MAC层研究

基于Markov链理论提出了一种新的理论模型用于描述无线传感器网络MAC层回退机制,该模型重点考虑了密集分布的无线传感器节点中普遍存在的捕获效应,并给出了新模型下节点发送概率的解析解。在此基础上,进而提出了一种新的无线传感器网络吞吐率计算模型,通过仿真分析,基于该模型计算所得到的网络吞吐率理论值要大于没有考虑捕获效应的网络吞吐率理论值。因此提出的新模型能够更准确地描述捕获效应对无线传感器网络的影响。     

一种应用于Ad Hoc无线局域网的随机接入协议

本文分析了应用于Ad Hoc无线局域网的BSAC(Buffered Slotted ALOHA CDMA)随机接入协议,并且首次提出了采用Markov(马尔可夫)链方法的分析模型.此模型应用两个Markov链模型,一个表示节点中的M/M/1/k排队模型,另一个表示网络中活动节点数量.两个Markov链模型通过节点空闲概率相互联系.在此模型基础上,本文详细分析了扩频增益、队列长度与最大允许重传次数等输入参数对网络吞吐量、平均延迟与丢包概率等性能尺度的影响,推导得出了BSAC协议的吞吐量极限.另外,本文还引入多数据包接收技术-延迟捕获技术,该项技术可以有效降低数据包冲突概率,相对于没有采用延迟捕获技术的BSAC协议,平均提高吞吐量29.1%,最大吞吐量提高20.8%,使网络性能接近于理论极限.     

一种基于马氏链的可容侵网络状态评估模型

分析了可容侵网络的运行状态转移过程,在此基础上提出了一种基于马氏链的可客侵网络状态评估模型,并给出了计算实例.该模型可用于对可容侵网络性能进行评估.     

一种应用于Ad Hoc无线局域网的随机接人协议

本文分析了应用于Ad Hoe无线局域网的BSAC(Buffered Slotted ALOHA CDMA)随机接入协议，并且首次提出了采用Markov(马尔可夫)链方法的分析模型．此模型应用两个Markov链模型，一个表示节点中的M／M／I／k排队模型，另一个表示网络中活动节点数量．两个Markov链模型通过节点空闲概率相互联系．在此模型基础上，本文详细分析了扩频增益、队列长度与最大允许重传次数等输入参数对网络吞吐量、平均延迟与丢包概率等性能尺度的影响，推导得出了BSAC协议的吞吐量极限．另外，本文还引入多数据包接收技术一延迟捕获技术，该项技术可以有效降低数据包冲突概率，相对于没有采用延迟捕获技术的BSAC协议，平均提高吞吐量29．1％，最大吞吐量提高20．8％，使网络性能接近于理论极限．     

基于Markov攻击图和博弈模型的区块链安全态势感知方法

全面准确地感知区块链网络中各节点所遭受的日蚀攻击情况是一个难题,该文针对该难题提出一种基于Markov攻击图和博弈模型的区块链安全态势感知方法。该方法结合区块链网络各节点以及日蚀攻击的特点建立Markov攻击图模型,随后将该模型进行量化从而计算各攻击路径的转换概率,选择较高概率的攻击路径进行多阶段攻防博弈并计算双方的最大目标函数值。通过分析这些函数值,完成对整个区块链网络节点的安全态势感知,达到对未来安全情况的预测和系统维护的目的。实验对比表明,该模型方法不但具有较低的入侵成功次数,还具有较好的确保系统完整性等方面的优势。     

基于聚合度的地域通信网关键节点识别方法

分析了地域通信网的网络模型,从网络的拓扑结构出发,以图论知识为基础,把节点的度数和聚合度作为衡量节点重要性的标准,给出了关键节点的定义方法,通过分析对比得出地域通信网中有些关键节点并不具有较大的度分布特征,而且链路之间存在着一定的差别,采用度作为节点重要性的评估方法具有一定的片面性。在此基础上,文中提出了一种基于聚合度大小排序的关键节点识别方法,并给出了关键节点识别流程。实例分析结果表明了该方法的有效性、简单性和准确性。     

聚类系数大小及分布可调的BBV网络演化模型

在传统BBV模型的基础上,提出了一种改进的BBV网络演化模型。基本思想是改变网络增长过程中新节点加入时,新旧节点的连接方式及优先选择概率。该模型不仅可以调节无标度加权网络度和强度的分布,还可以通过改变“三角形”连接概率公式中系数的大小,增大网络的聚类系数并调节网络聚类系数的分布。即根据实际需要,大范围调节网络度分布,精确调节聚类系数大小及分布,其生成机制更符合实际网络的演化过程。     

基于层次混合的高效概率包标记WSNs节点定位算法

在利用概率包标记技术对无线传感器网络(WSN)恶意节点的追踪定位中,标记概率的确定是关键,直接影响到算法的收敛性,最弱链,节点负担等方面。该文分析并指出了基本概率包标记(BPPM)和等概率包标记(EPPM)方法的缺点,提出了一种层次式混合概率包标记(LMPPM)算法,可以克服以上算法的不足。该算法对无线传感器网络进行分簇,将每个簇看成一个大的簇节点,整个网络由一些大的簇节点构成,每个簇节点内部又包含一定数量的传感器节点。在簇节点之间采用等概率包标记法,在簇节点内部采用基本概率包标记法。实验分析表明,该算法在收敛性、最弱链方面优于BPPM算法,在节点计算与存储负担方面优于EPPM算法,是在资源约束条件下的一种整体优化。     

FUCEM: futuristic cooperation evaluation model using Markov process for evaluating node reliability and link stability in mobile ad hoc network

The cooperation between the nodes is one of the potential factor for successful routing in mobile ad hoc networks. The non-cooperative behaviour of the node disturbs the routing as well as degrades network performances. The non-cooperativeness is due to the resource constraint characteristics of a mobile node. The battery energy is an important constraint of a node because it exhausts after some period. On the other side, the mobility of nodes also affects routing performances. Hence, this work concentrates on evaluating cooperation of a node by probing future node energy and mobility. This paper proposes a futuristic cooperation evaluation model (FUCEM) for evaluating node reliability and link stability to establish effective routing. The FUCEM model examines influencing factors of cooperation and state transition of nodes using Markov process. Node reliability and link stability manipulated through the Markov process. The Markov process helps in fixing the upper and lower bounds of the cooperation and calculates the cooperation factor. The NS2 simulator simulates the proposed work and evaluates performance results with different scenarios. The result indicates that the proposed FUCEM has 13–21% higher packet delivery ratio than other algorithms. The remaining energy of the nodes increases to 6–7% as compared with the existing algorithms in a higher mobility scenario. Further, it significantly improves the results of routing overhead and average end-to-end delay than the existing models.

     

用马尔科夫模型优化分布式最小连通支配集算法

 为了提高无线传感器网络(WSNs)的能量利用效率、延长网络的生存时间,对基于极大独立集的最小连通支配集算法(MISB)进行优化,提出了一种新的算法.本文首先应用离散马尔科夫链为节点建立模型,并且根据模型预测节点的能量消耗;本算法进行多轮选举,每一轮开始时根据节点的度和能量选举支配点,依据模型预测的能量消耗决定本轮的运行时间,本轮运行结束时从新选举支配点,开始新一轮.仿真结果表明,本算法和原算法相比可以更好地平衡网络的能量消耗,提高全网的能量利用率,极大地延长网络的生存时间.     

基于最短路径数的WSN抗毁性评价方法

从已有的基于全网的等效最短路径数的抗毁性出发,应用到以数据为中心的无线传感器网络各个簇的抗毁性衡量中。进而用簇的抗毁性来衡量整个无线传感器网络的抗毁性。并对基于小世界模型的无线传感器网络抗毁性进行了抗毁性分析。仿真结果表明,该评估模型能更客观、准确地评估以数据为中心的无线传感器网络的抗毁性。     

基于节点的地域通信网抗毁性评价及应用

分析了战场条件下地域通信网抗毁性评价的需求和现有地域通信网抗毁性评价方法存在的不足,确定了节点失效条件下地域通信网抗毁性评价的标准和计算流程。从节点失效的实际出发,给出了节点重要度的分析方法,并以该方法为基础,综合考虑节点逐个失效的整个过程,给出了基于节点的地域通信网抗毁性评价方法。最后,将这种方法应用于地域通信网拓扑优化,并给出了应用实例。     

机动干线通信网抗毁评估方法

机动干线通信网具有机动、灵活、多变性,对网络的抗毁性、可靠性、生存性有着特殊的要求。针对机动干线通信网的特点,提出一种快速评价网络整体抗毁性的方法,给出抗毁性定量计算的数学解析式,同时给出网络中各节点、链路对网络抗毁能力的贡献量度。建立合理、有效的抗毁量度指标对机动干线通信网络优化、网络调整以及网络评估都有着重要意义。     

Lightweight opportunistic routing forwarding strategy based on Markov chain

A lightweight opportunistic routing forwarding strategy (MOR) was proposed based on Markov chain.In the scheme,the execute process of network was divided into a plurality of equal time period,and the random encounter state of node in each time period was represented by activity degree.The state sequence of a plurality of continuous time period constitutes a discrete Markov chain.The activity degree of encounter node was estimated by Markov model to predict its state of future time period,which can enhance the accuracy of activity degree estimation.Then,the method of comprehensive evaluating forwarding utility was designed based on the activity degree of node and the average encounter interval.MOR used the utility of node for making a routing forwarding decision.Each node only maintained a state of last time period and a state transition probability matrix,and a vector recording the average encounter interval of nodes.So,the routing forwarding decision algorithm was simple and efficient,low time and space complexity.Furthermore,the method was proposed to set optimal number of the message copy based on multiple factors,which can effectively balance the utilization of network resources.Results show that compared with existing algorithms,MOR algorithm can effectively increase the delivery ratio and reduce the delivery delay,and lower routing overhead ratio.     

Routing protocol based on social characteristics for opportunistic networks简

Opportunistic networks are derived from delay tolerant networks, where mobile nodes have no end-to-end connections. Nodes are represented by people, which means that opportunistic networks can be regarded as social networks. Human mobility plays an important role in affecting the performance of forwarding protocols in social networks, furthermore, the trajectory of people＇s movements are driven by social characteristics. However, current routing protocols rely on simple mobility models, and rarely consider social characteristics. Considering two heterogeneous network models, an social opportunistic networks routing（SONR） was proposed which brings an adapted discrete Markov chain into nodes＇ mobility model and calculates the transition probability between successive status. Comparison was made between Spray, Wait and Epidemic protocol. Simulation show that SONR can improve performance on delivery ratio, delivery latency and network overhead, meanwhile. SONR approaches the performance of Epidemic routing.     

短波网基于节点的抗毁性评估

给出了短波网基于节点的抗毁性定义和相应的评价方法。与通常的抗毁性评估方法相比,该方法简单有效,不需要大量复杂的计算。理论分析和实例均表明该方法是可行的。     

Reference node selection in dynamic tree

The reference node (RN) is a central node that has minimum distance/hop count to all other nodes in the network. This central node can play several critical roles such as being the time reference in order to synchronise computer nodes. For synchronisation, the main goal is to minimise the sum of synchronisation errors. The time synchronisation error, known for each link between two nodes, accumulates for each hop along the path used for synchronisation between two nodes. In such a context, the best RN is defined as having the minimal sum of time synchronisation errors between itself and every other node. Thus, the first step for error minimisation is to select a minimum spanning tree (MST), formed by the links with minimum synchronisation error, as synchronisation path. The second step is to select an RN, which minimises the sum of synchronisation errors to all nodes in the MST, as time reference for synchronisation. In a dynamic network, where communication links appear and disappear, and synchronisation accuracy improves as more packets are exchanged, a static RN would entail suboptimal synchronisation accuracy. All existing models in this area are limited to static RNs because of the computing cost of updating the RN, yielding a suboptimal total synchronisation error over time and causing problems if the selected node is removed from the dynamic network. This paper presents a novel and efficient method for dynamic RN selection in dynamic networks. The approach proposed in this paper improves the performance of RN computation and update in live mode for dynamic networks. This new method concentrates on the altered path with respect to the RN, each time the MST is updated. This provides an efficient way to find and maintain a RN incrementally in an average time complexity of O(log n) per update, which n is the total number of nodes in the network. The proposed approach was tested with a huge dynamic network containing 60 000 simulated nodes, in a number of different situations. The proposed approach achieves excellent running time while minimising synchronisation error. Although this work is currently used for time synchronisation purposes, several dynamic network tools can benefit from an efficient incremental algorithm to calculate hop counts and select a central point for the network. Copyright © 2014 John Wiley & Sons, Ltd     

Space and network diversity combination for masked node collision resolution in wireless ad hoc network

In wireless ad hoc networks, the traditional carrier sensing multiple access/collision avoidance protocol cannot solve the masked node problem, which affects the network performance greatly. Our proposed collision separation technique overcomes the shortcoming of the IEEE 802.11 request-to-send-clear-to-send handshake by combining the space diversity provided by the antenna array and network diversity provided by the medium access control layer. In this work, the colliding packets caused by masked nodes are not discarded but stored and combined with the selected retransmission packets to separate the data from different nodes. The steady states of the nodes in the network are analyzed via a Markov chain model. The network throughput and delay performance are also investigated. Compared to network assisted diversity multiple access, our proposed method can provide significantly higher throughput and lower delay