共查询到18条相似文献，搜索用时 625 毫秒
1.
Fan-rui Kong Chun-wen Li Qing-qing Ding Guang-zhao Cui Bing-yi Cui 《浙江大学学报(A卷英文版)》2009,10(2):279-289
As the applications of wireless sensor networks （WSNs） diversify, providing secure communication is emerging as a critical requirement. In this paper, we investigate the detection of wormhole attack, a serious security issue for WSNs. Wormhole attack is difficult to detect and prevent, as it can work without compromising sensor nodes or breaching the encryption key. We present a wormhole attack detection approach based on the probability distribution of the neighboring-node-number, WAPN, which helps the sensor nodes to judge distributively whether a wormhole attack is taking place and whether they are in the influencing area of the attack. WAPN can be easily implemented in resource-constrained WSNs without any additional requirements such as node localization, tight synchronization, or directional antennas. WAPN uses the neighboring-node-number as the judging criterion, since a wormhole usually results in a significant increase of the neighboring-node-number due to the extra attacking link. Firstly, we model the distribution of the neighboring-node-number in the form of a Bernoulli distribution. Then the model is simplified to meet the sensor nodes＇ constraints in computing and memory capacity. Finally, we propose a simple method to obtain the threshold number, which is used to detect the existence of a wormhole, Simulation results show that WAPN is effective under the conditions of different network topologies and wormhole parameters. 相似文献
2.
Multicasting is a communication service that allows an application to efficiently transmit copies of data packets to a set of destination nodes. The problem of finding a minimum cost multicast tree can be formulated as a minimum Steiner tree problem in networks, which is NP-completeness. MPH (minimum path cost heuristic) algorithm is a famous solution to this problem. In this paper,we present a novel solution TPMPH (two phase minimum path cost heuristic) to improve the MPH by generating the nodes and the edges of multicast tree separately. The cost of multicast tree generated by the proposed algorithm with the same time as MPH is no more than that of MPH in the worst case. Extensive simulation results show that TPMPH can effectively improve the performance on MPH, and performs better in large-scale networks and wireless networks. 相似文献
3.
The cumulative sum （CUSUM） algorithm is proposed to detect the selfish behavior of a node in a wireless ad hoc network. By tracing the statistics characteristic of the backoff time between successful transmissions, a wireless node can distinguish if there is a selfish behavior in the wireless network. The detection efficiency is validated using a Qualnet simulator. An IEEE 802.11 wireless ad hoc network with 20 senders and 20 receivers spreading out randomly in a given area is evaluated. The well-behaved senders use minimum contention window size of 32 and maximum con- tention window size of I 024, and the selfish nodes are assumed not to use the binary exponential strategy for which the contention window sizes are both fixed as 16. The transmission radius of all nodes is 250 m. Two scenarios are investigated： a single-hop network with nodes spreading out in 100 m~100 m, and all the nodes are in the range of each other; and a multi-hop network with nodes spreading out in 1 000 m~ 1 000 m. The node can monitor the backoff time from all the other nodes and run the detection algorithms over those samples. It is noted that the threshold can significantly affect the detection time and the detection accuracy. For a given threshold of 0.3 s, the false alarm rates and the missed alarm rates are less than 5%. The detection delay is less than 1.0 s. The simulation results show that the algorithm has short detection time and high detection accuracy. 相似文献
4.
In this paper we introduce a novel energy-aware routing protocol REPU （reliable, efficient with path update）, which provides reliability and energy efficiency in data delivery. REPU utilizes the residual energy available in the nodes and the received signal strength of the nodes to identify the best possible route to the destination. Reliability is achieved by selecting a number of intermediate nodes as waypoints and the route is divided into smaller segments by the way-points. One distinct advantage of this model is that when a node on the route moves out or fails, instead of discarding the whole original route, only the two way-point nodes of the broken segment are used to find a new path. REPU outperforms traditional schemes by establishing an energy-efficient path and also takes care of efficient route maintenance. Simulation results show that this routing scheme achieves much higher performance than the classical routing protocols, even in the presence of high node density, and overcomes simultaneous packet forwarding. 相似文献
5.
The growth and evolution of the knowledge network in supply chain can be characterized by dynamic growth clustering and non-homogeneous degree distribution.The networks with the above characteristics are also known as scale-free networks.In this paper,the knowledge network model in supply chain is established,in which the preferential attachment mechanism based on the node strength is adopted to simulate the growth and evolution of the network.The nodes in the network have a certain preference in the choice of a knowledge partner.On the basis of the network model,the robustness of the three network models based on different preferential attachment strategies is investigated.The robustness is also referred to as tolerances when the nodes are subjected to random destruction and malicious damage.The simulation results of this study show that the improved network has higher connectivity and stability. 相似文献
6.
《天津大学学报(英文版)》2010,(2)
The cumulative sum (CUSUM) algorithm is proposed to detect the selfish behavior of a node in a wireless ad hoc network. By tracing the statistics characteristic of the backoff time between successful transmissions, a wireless node can distinguish if there is a selfish behavior in the wireless network. The detection efficiency is validated using a Qualnet simulator. An IEEE 802.11 wireless ad hoc network with 20 senders and 20 receivers spreading out randomly in a given area is evaluated. The well-behaved senders use minimum contention window size of 32 and maximum contention window size of 1 024, and the selfish nodes are assumed not to use the binary exponential strategy for which the contention window sizes are both fixed as 16. The transmission radius of all nodes is 250 m. Two scenarios are investigated: a single-hop network with nodes spreading out in 100 m×100 m, and all the nodes are in the range of each other; and a multi-hop network with nodes spreading out in 1 000 m×1 000 m . The node can monitor the backoff time from all the other nodes and run the detection algorithms over those samples. It is noted that the threshold can significantly affect the detection time and the detection accuracy. For a given threshold of 0.3 s, the false alarm rates and the missed alarm rates are less than 5%. The detection delay is less than 1.0 s. The simulation results show that the algorithm has short detection time and high detection accuracy. 相似文献
7.
A network model is proposed to support service differentiation for mobile Ad Hoc networks by combining a fully distributed admission control approach and the DIFS based differentiation mechanism of IEEE802.11. It can provide different kinds of QoS (Quality of Service) for various applications. Admission controllers determine a committed bandwidth based on the reserved bandwidth of flows and the source utilization of networks. Packets are marked when entering into networks by markers according to the committed rate. By the mark in the packet header, intermediate nodes handle the received packets in different manners to provide applications with the QoS corresponding to the pre-negotiated profile. Extensive simulation experiments showed that the proposed mechanism can provide QoS guarantee to assured service traffic and increase the channel utilization of networks. 相似文献
8.
Peer-to-peer (P2P) systems are now very popular. Current P2P systems are broadly of two kinds, structured and unstructured. The tree structured P2P systems used technologies such as distributed hash tables (DHT) and hierarchical clustering can search the required target quickly, however, in a tree, the internal node has a higher load and its leave or crash often causes a large population of its offspring's problems, so that in the highly dynamic Internet environment the tree structure may still suffer frequent breaks. On the other hand, most widely used unstructured P2P networks rely on central directory servers or massive message flooding, clearly not scalable. So, we consider both of the above systems' advantages and disadvantages and realize that in the P2P systems one node may fail easily, but that when a number of nodes organized as a set, which we call "super node", the set is robust. Super nodes can be created and updated aware of topology-aware, and used with simple protocol such as flooding or "servers" to exchange information. Furthermore the entire robust super node can be organized into exquisite tree structure. By using this overlay network architecture, P2P systems are robust, efficient, scalable and secure. The simulation results demonstrated that our architecture greatly reduces the alteration time of the structure while decreasing the average delay time, compared to the common tree structure. 相似文献
9.
This paper presents a node shift method to find the optimal distribution of nodes in single-layer reticulated shells. The optimization process searches for the minimum strain energy configuration and this leads to reduced sensitivity in initial imper- fections. Strain energy sensitivity numbers are derived for free shift and restricted shift where nodes can move freely in the 3D space or have to move within a predefmed surface respectively. Numerical examples demonstrate the efficiency of the proposed approach. It was found that optimized structures achieve higher ultimate load and are less sensitive to imperfections than the initial structure. The configuration of the final structure is closely related to factors like the initial structural configuration, spatial conditions, etc. Based on different initial conditions, architects can be provided with diverse reasonable structures. Furthermore, by amending the defined shapes and nodal distributions, it is possible to improve the mechanical behavior of the structures. 相似文献
10.
Forward and backward models for fault diagnosis based on parallel genetic algorithms 总被引：2，自引：0，他引：2
In this paper, a mathematical model consisting of forward and backward models is built on parallel genetic algorithms （PGAs） for fault diagnosis in a transmission power system. A new method to reduce the scale of fault sections is developed in the forward model and the message passing interface （MPI） approach is chosen to parallel the genetic algorithms by global single-population master-slave method （GPGAs）. The proposed approach is applied to a sample system consisting of 28 sections, 84 protective relays and 40 circuit breakers. Simulation results show that the new model based on GPGAs can achieve very fast computation in online applications of large-scale power systems. 相似文献
11.
该文提出一种基于节点层的安全体系结构,结合组钥密分配和身份识别加密,建立钥密分配方案.该方法能使两个节点互相确认身份后,在安全的环境中进行通信,同时,组与组也能保证在安全环境下通信.抵抗攻击的能力的结果说明,Sybil攻击,节点增加攻击,节点复制攻击都能有效的被制止.仿真表明,文中提出的安全体系结构是安全可行的. 相似文献
12.
In order to evaluate all attack paths in a threat tree,based on threat modeling theory,a weight distribution algorithm of the root node in a threat tree is designed,which computes threat coefficients of leaf nodes in two ways including threat occurring possibility and the degree of damage.Besides,an algorithm of searching attack path was also obtained in accordence with its definition.Finally,an attack path evaluation system was implemented which can output the threat coefficients of the leaf nodes in a target threat tree,the weight distribution information,and the attack paths.An example threat tree is given to verify the effectiveness of the algorithms. 相似文献
13.
提出一种改进的并行比特翻转算法. 为了加快校验节点和变量节点之间的信息传递速率, 算法中的比特翻转及校验和更新2个步骤采用并行化处理. 仿真结果表明, 改进后的算法相对于原有的并行比特翻转算法在误帧率性能上能够取得0.1～0.3 dB的增益. 同时, 改进算法在译码吞吐率的性能上也有所改善. 此外, 还讨论了翻转门限的选择方法, 这些门限决定了每次迭代中哪些比特需要被翻转. 通过选择合适的翻转门限, 可使错误的比特尽量多地被翻转, 并避免翻转正确的比特. 该改进算法比较适用于对具有准循环结构的LDPC码进行译码. 相似文献
14.
利用窄带通信(frequency divided multiple access,FDMA)技术在远距离通信上的优势,设计了基于DPMR(digital private mobile radio)数字对讲无线通信协议的无线传感器节点。采用C8051F120为主控微处理器,DPMR通信部分选用数字基带处理器SCT3252F及士康公司SRT3500系列套片组成的射频单元,软件上可实现多点分时上传传感器数据。节点最大发射功率为4W,接收灵敏度小于0.2μV,在城市较空旷环境下实测有效通信距离可达3.4km,适合于较大范围内无线传感器网络的应用需要。 相似文献
15.
GUO Tong-qiang WENG Jian-guang ZHUANG Yue-ting 《浙江大学学报(A卷英文版)》2007,8(12):1983-1989
P2P systems are categorized into tree-based and mesh-based systems according to their topologies. Mesh-based systems are considered more suitable for large-scale Internet applications, but require optimization on latency issue. This paper proposes a content subscribing mechanism (CSM) to eliminate unnecessary time delays during data relaying. A node can send content data to its neighbors as soon as it receives the data segment. No additional time is taken during the interactive stages prior to data segment transmission of streaming content. CSM consists of three steps. First, every node records its historical segments latency, and adopts gamma distribution, which possesses powerful expression ability, to express latency statistics. Second, a node predicts subscribing success ratio of every neighbor by comparing the gamma distribution parameters of the node and its neighbors before selecting a neighbor node to subscribe a data segment. The above steps would not increase latency as they are executed before the data segments are ready at the neighbor nodes. Finally, the node, which was subscribed to, sends the subscribed data segment to the subscriber immediately when it has the data segment. Experiments show that CSM significantly reduces the content data transmission latency. 相似文献
16.
有保证的调度对硬实时系统是必须的 ,这是因为系统中每个进程必须满足它们的截止时间 ,否则后果不堪设想 .本文讨论了两种有保证的调度算法 ,它们是分支限界法和回溯法 ,给出了用这两种算法寻找最优解的过程 ,提出逻辑结点和物理结点的概念 .通过对多个进程集合寻找最优解的实验 ,对两种算法在产生的结点个数、比较次数、搜索树的拓扑结构及占用的内存空间等方面进行了比较 相似文献
17.
Localization of the sensor nodes is a key supporting technology in wireless sensor networks (WSNs). In this paper, a real-time
localization estimator of mobile node in WSNs based on extended Kalman filter (KF) is proposed. Mobile node movement model
is analyzed and online sequential iterative method is used to compute location result. The detailed steps of mobile sensor
node self-localization adopting extended Kalman filter (EKF) is designed. The simulation results show that the accuracy of
the localization estimator scheme designed is better than those of maximum likelihood estimation (MLE) and traditional KF
algorithm. 相似文献
18.
杨敬杰 《宁波职业技术学院学报》2007,11(2):86-88,93
采用以广播为技术基础的以太网,任何两个节点之间的通信数据包,不仅为这两个节点的网卡所接收,也同时为处在同一以太网上的任何一个节点的网卡所截取。因此,黑客只要接入以太网上的任一节点进行侦听,就可以捕获发生在这个以太网上的所有数据包,对其进行解包分析,从而窃取关键信息,这就是以太网所固有的安全隐患。对此,可以采用网络分段、交换式集线器代替共享集线器和VLAN的划分措施来实现其数据传输的安全。 相似文献