节点移动性对MANETs网络拓扑特征的影响

在影响MANETs网络性能的众多因素之中,动态变化的网络拓扑结构是不可忽视的一个重要方面,而节点的移动特性是导致MANET网络拓扑变化的主要原因之一,因此研究节点的移动性对网络拓扑结构特性的影响具有重要的意义。采用复杂网络理论研究节点移动性对MANET网络拓扑结构统计特性的影响。介绍复杂网络的基本统计特性参数,通过仿真实验,详细分析了几种经典节点移动模型下,节点移动速度、信号辐射半径、节点密度等参数对MANET网络的平均度、聚类系数和调和平均最短路径长度的影响。结果表明节点的移动方式对MANET网络拓扑结构统计特性产生不同的影响。     

Towards reliable self-clustering Mobile Ad Hoc Networks

With the introduction of Mobile Ad Hoc Networks (MANETs), nodes are able to participate in a dynamic network which lacks an underlying infrastructure. In this paper, we present a novel approach to improve the search efficiency and scalability of MANETs by clustering nodes based on trust mechanism. In our method, the trust relationship is formed by evaluating the level of trust using Bayesian statistic analysis, and clusters can be formed and maintained autonomously by nodes with only partial knowledge. Simulation results show that each node can form and join proper clusters based on their trust degree, and the cluster-based search algorithm with trust mechanism outperforms over those in current popular clustering models.     

PassCAR: A passive clustering aided routing protocol for vehicular ad hoc networks

Vehicular ad hoc networks (VANETs) are a promising architecture for vehicle-to-vehicle communications in the transportation field. However, the frequent topology changes in VANETs create many challenges to data delivery because the vehicle velocity varies with time. Thus, designing an efficient routing protocol for stable and reliable communication is essential. Existing studies show that clustering is an elegant approach to efficient routing in a mobile environment. In particular, the passive clustering (PC) mechanism has been validated as a more efficient approach compared to traditional clustering mechanisms. However, the PC mechanism was primarily designed for mobile ad hoc networks (MANETs), and may be unsuitable for constructing a cluster structure in VANETs because it does not account for vehicle behavior and link quality. In this paper, we propose a passive clustering aided routing protocol, named PassCAR, to enhance routing performance in the one-way multi-lane highway scenario. The main goal of PassCAR is to determine suitable participants for constructing a stable and reliable cluster structure during the route discovery phase. Each candidate node self-determines its own priority to compete for a participant using the proposed multi-metric election strategy based on metrics such as node degree, expected transmission count, and link lifetime. Simulation results show that, compared with the original PC mechanism, PassCAR not only increases the successful probability of route discovery, but also selects more suitable nodes to participate in the created cluster structure. This well-constructed cluster structure significantly improves the packet delivery ratio and achieves a higher network throughput due to its preference for reliable, stable, and durable routing paths.     

移动自组网中一种轻量型的密钥分量更新协议*

提出一种面向移动自组网环境的轻量型的密钥分量更新协议,是对Amir Herzberg等人提出的密钥分量更新协议的改进方案。该协议在每个更新周期开始时选举一个认证节点作为辅助节点,辅助节点在更新自己的密钥分量的同时辅助其他认证节点完成密钥分量的更新。因此,该协议可有效地降低密钥分量更新时所花费的通信代价,从而可以满足移动自组网中每个节点地位平等且可以自由移动等要求。研究结果表明：增设辅助节点不会影响密钥分量更新协议的安全性。     

Alliance-based clustering scheme for group key management in mobile ad hoc networks

Several protocols have been proposed to deal with the group key management problem in mobile ad hoc networks (MANETs). Most of these protocols organize the network into clusters to reduce the cost of key refresh or rekeying. Rekeying constitutes a challenging issue in group key management because it must be launched whenever the constitution of the group is altered following a leave or a join operation. However, cluster maintenance may also generate significative communication overhead. So, the clustering algorithm is an important factor in the performance of any key management solution. A clustering algorithm that ensures stable clusters in spite of mobility is very appreciable in mobile ad hoc networks. In fact, all the overhead due to the traffic generated by cluster adjustments and the related rekeying procedures will be saved. As far as we know, no existing clustering algorithm takes into account self-stabilization while relying on the mobility resilience of graph alliances. In this paper, we propose a fully distributed and self-stabilizing clustering algorithm for key management in MANETs where each cluster is an alliance.     

A Mechanism for Communication-Efficient Broadcast Encryption over Wireless Ad Hoc Networks

Due to its low communication cost, stateful broadcast encryption is an appealing solution for secure content distribution in mobile ad hoc wireless networks (MANETs). Unfortunately, the inherent limitations of MANETs prevent a standard application of such schemes since they require receivers to be online. In this paper, we present a reliable message delivery mechanism for MANETs that is based on erasure codes and that leverages node mobility in order to achieve non-interactive recovery of missed messages. We then show how our mechanism can be used to reliably deliver the key updates of a stateful broadcast encryption scheme. Our solution has several useful properties: it allows trade-offs between the amount of storage required at each node and the speed of message recovery; and it has the ability to leverage the resources of unauthorized nodes. We evaluate the performance of our approach through simulation, and show that it achieves good performance for networks with high node density.     

Volunteer nodes of ant colony optimization routing for minimizing delay in peer to peer MANETs

A Mobile ad hoc Network (MANET) is an infrastructure less network that permits nodes to make a wireless network with mobility. In MANETs, the node linkages breaks are frequent due to all nodes are in movement. When neighbor nodes travel out of other node communication range connection among both mobile nodes breaks. Thus it makes delay and packet loss in the network. In the present Traffic Control method, several times, since the highest traffic, heavy rain, accidents, or other reasons, there may be probabilities of jam on roads. Thus, people could get delay owing to the highest traffic. Therefore, it is highly preferred to have an effective way to track the traffic on roads and thus select the suitable road that is traffic free. To resolve these problems, the volunteer Nodes of Ant Colony Optimization Routing (VNACO) is proposed. The primary objective of VNACO is to reduce both the delay and routing overhead in Peer to Peer (P2P) MANETs. Here, peer node act as a volunteer node and mobile node for transmitting data from source to destination. During data transmission, the relay node moving out of communication range when the volunteer node overheard the dropped data packet then deliver the data to the corresponding relay node. As a result, minimizes both the delay and packet losses. In VNACO, the volunteer’s nodes are elected based on node aptitude. Node aptitude is calculated by iterating node connectivity, transmission processing time, node energy and available bandwidth. In addition, an ant colony optimization algorithm to finds the optimal route and reduce the routing overhead in P2P MANETs. The significant application of this mechanism is utilized for the traffic management system. Network simulation results indicate that the VNACO mechanism is minimizing 22% delay and reducing 14% packet losses compared to the baseline protocol.

     

Improved encryption protocol for secure communication in trusted MANETs against denial of service attacks

MANET(Mobile Adhoc Networks) possess the open system condition, absence of central server, mobile nodes that make helpless to security assault while conventional security components couldn’t meet MANET security prerequisites in view of restricted correspondence data transfer capacity, calculation power, memory and battery limit in addition to the vitality enabled environment. The trusted MANETs provide a reliable path and efficient communication but the secrecy of the trust values sometimes may be overheard by the masqueraders. Due to the need of the clustered MANETs the exchange of mathematical values remains to be a necessary part. In the proposed security of the trusted MANETs is focused so as to provide rigid and robust networks when additional resources are added. For clustering of the nodes LEACH protocol is suggested in which the CHs and CMs are fixed for the data transfer in the network. The energy is disseminated in the LEACH as to avoid the battery drain and network fatal. Hence to add resistance and to make an authentic network, the encryption and decoding is incorporated as a further supplementary to avoid the denial of service attacks, we have utilized DoS Pliancy Algorithm in which the acknowledgment based flooding attacks is focused. Likewise the encoded messages from the source node in one cluster can be recoded in the transmission stage itself to reproduce the messages. Contrasted with the past works, QoS of our proposed work has been made strides when tested with black hole and sink hole attacks. Simulation results shows that the DoS pliancy scheme works better and efficient when compared to the existing trust based systems.

     

一种基于通讯痕迹的社会网络团伙分析模型

研究在已知目标团伙中某节点以及目标团伙特征的前提下,基于通讯痕迹特征寻找社会网络团伙。研究过程中引入了社会圈、节点中心度和事件集合关联矩阵等概念,重点将聚类分析方法与社会团伙发现相结合,以期得到一种基于通讯痕迹的社会网络团伙分析模型。     

结合二层节点度和聚类系数的链路预测算法

研究复杂网络的链路预测算法对分析舆论传播方向、预测舆论演进趋势和控制舆论发展进程具有重要意义。针对现有的基于节点度的链路预测算法存在预测质量偏低的问题,提出了一种结合二层节点度和聚类系数的链路预测算法。算法全面考虑网络局部结构信息以及共同邻居节点之间的差异性,在相似性评价指标的选择上将节点度和聚类系数结合,深度挖掘节点相似性性质并将节点度扩展到二层。最后在三个真实数据集中分别进行仿真实验,结果表明提出的算法相比于Common Neighbors、Adamic-Adar和Resource Allocation等经典算法具有更好的性能。