共查询到20条相似文献,搜索用时 15 毫秒
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考虑到在无线传感器网络中,新节点的加入或老节点的死亡均会导致拓扑呈动态变化,该文研究一种完全分布式二阶一致性时间同步(Second-Order Consensus Time Synchronization, SOCTS)算法。将节点的时钟特性建模成二阶状态方程,按照伪同步周期广播节点的本地虚拟时间,根据邻居节点的本地虚拟时间的不一致来构造同步控制输入;通过坐标变换将网络的一致性时间同步问题转化为变换系统的稳定性问题,理论分析了SOCTS算法的收敛性和收敛条件,并研究了影响SOCTS算法收敛速度的因素。通过数值仿真实验验证了所提方法的有效性。 相似文献
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Haitao Wan Jean-François Diouris Guillaume Andrieux 《Wireless Personal Communications》2012,63(4):977-993
Time synchronization is crucial for the implementation of cooperative communication in wireless sensor networks. In this paper,
we explore the effect of synchronization error on cooperative communication utilizing distributed Alamouti code. The analysis
and simulation results show that small synchronization error has negligible effect on bit error rate (BER) performance. In
order to synchronize the distributed sensor nodes within an acceptable error, we propose a physical layer synchronization
scheme. This scheme consists of an initial synchronization of the cooperative transmitters, synchronization error estimation
at the cooperative receiver and finally a feedback phase. A maximum likelihood method is proposed to make the synchronization
error estimation. It achieves better performance than the matched filter method at the price of moderate increase in computational
complexity and memory space. Two strategies after synchronization error estimation have been analyzed. They provide better
BER performance in the existence of initial synchronization error. They are practical to be implemented in the sensor nodes
before the Alamouti decoding. 相似文献
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无线传感器网络典型时间同步技术分析 总被引:1,自引:0,他引:1
从无线传感器网络特点出发,结合三种时间同步模型及已有的时间同步算法,根据评价时间同步算法性能的指标,对典型的时间同步算法性能进行了分析评估,为进一步改进时间同步算法的性能提供了帮助 相似文献
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Wireless Personal Communications - Wireless sensor and actuator networks (WSANs) consists of a large number of sensors and a relatively small number of actuators connected through wireless links.... 相似文献
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针对无线传感器网络全网多跳自适应时间同步效率低的问题,在接收端与接收端同步模型基础上,该文提出一种自适应高效无线传感器网络时间同步优化算法(AEO)。首先,双节点同步时,从节点接收来自参考节点的同步消息并进行确认,在同步周期结束后通过拟合估计和数据更新完成时间修正,构建交互参数同步包,并与主节点进行信息交换完成同步过程。其次,全网同步时,建立Voronoi多边形拓扑结构,认定拓扑结构中参考节点和邻域节点身份(ID),参考节点覆盖区域间通过邻域节点交换同步信息,实现自适应多区域节点联合时间同步。仿真结果表明该算法在双节点时间同步中能够保证同步误差较小,网络能耗较低;同时,Voronoi拓扑相较于其他典型拓扑,在连通效率和收敛时间方面均有所改进。 相似文献
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传统的基于分组消息交换的无线传感器网络(WSN)同步方式很难做到同时兼顾同步精度和能耗.本文提出了一种基于分组消息交换的协作时间同步方法(CTS):对同步分组信息交互过程进行分析得出,协作中继的引入不会改变同步精度.通过协作中继对收发两端的同步分组信息进行接收转发来降低发射功率、降低能耗.理论分析和计算机仿真都表明在不降低同步精度的前提下,通过引入协作中继能达到降低能耗的目的,在视距信道模型中最大可达到4倍能耗效率. 相似文献
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Yinliang Jia Chiyu Zhang Kangwu Liang 《International Journal of Wireless Information Networks》2017,24(4):454-461
Wireless sensor networks (WSNs) need simple and effective approaches to reduce energy consumption because of limited energy. Clustering nodes is an effective approach to make WSNs energy-efficient. In this paper we propose a distributed multi-competitive clustering approach (DMCC) for WSNs. First, the nodes with high residual energy are selected to act as cluster head candidates (CHCs). Second, cluster heads (CHs) are selected from the CHCs based on a hybrid of competition. If the distances to the selected CHs are suitable, a CHC with more neighbor nodes and smaller average distance to its neighbor nodes is more likely to become a CH. If the number of CHs selected from the CHCs is insufficient, more CHs are selected from non-CHCs continually according to residual energy until the CHs number is suitable. DMCC makes the CHs number stable and distribute the CHs evenly. Simulation experiments were performed on to compare DMCC with some related clustering approaches. The experimental results suggest that DMCC balances the load among different clusters and reduces the energy consumption, which improves the network lifetime. 相似文献
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Research on wireless sensor networks (WSNs) has been receiving a lot of attention recently. Because of the constraints on the cost of hardware, there are a lot of restrictions regarding memory, computational ability, and energy consumption, hampering WSN research. So far, many key establishment schemes have been proposed for WSNs. For the proposed schemes, random key predistribution is a practical solution. With this, each sensor shares a common key with its neighbors via predistributed keys. However, it may happen that two sensor nodes do not share a common key. In this paper, an efficient grid-based pairwise key predistribution scheme for WSNs is proposed. In the proposed scheme, multiple polynomials for each row, each column, and each diagonal in the grid are constructed. Then, each sensor node in each row, column, and diagonal in the grid establishes a pairwise key with the other node using the predistributed symmetric polynomial. Simulation results demonstrate the effectiveness of the proposed scheme in increasing the probability of establishing pairwise keys and reducing communication overhead. 相似文献
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该文研究了基于分布式一致的无线传感器网络时间同步协议的收敛和加速问题。通过将其同步迭代过程映射到马尔可夫链的状态转移过程,推导出了分布式一致时间同步协议在循环网中的收敛速度与节点邻居数和网络规模有关。Matlab仿真实验表明该结论对类均匀规则网和类均匀网也是正确的。此外,对于类均匀网,邻居数分布也会影响协议的收敛速度。因此该文提出了基于改变网络邻居数分布的加速算法来提高分布式一致时间同步协议的收敛速度。规模为100个节点的类均匀网络实验结果表明,该文提出的加速算法在没有显著改变节点平均传输半径的情况下可使分布式一致时间同步协议的收敛迭代次数降低约25%。 相似文献
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Public Key-based (PKC) approaches have gained popularity in Wireless Sensor Network (WSN) broadcast authentication due to their simpler protocol operations, e.g., no synchronization and higher tolerance to node capture attack compared to symmetric key-based approaches. With PKC??s security strength, a sensor node that authenticates messages before forwarding them can detect a bogus message within the first hop. While this prevents forged traffic from wasting the sensor nodes?? energy, performing PKC operations in the limited computing-power sensor nodes can result in undesirably long message propagation time. At the other extreme, the sensor node can forward messages to other nodes prior to authenticating them. This approach diminishes propagation time with the trade-off of allowing forged messages to propagate through the network. To achieve swift and energy efficient broadcast operation, sensor nodes need to decide wisely when to forward first and when to authenticate first. In this paper, we present two new broadcast authentication schemes, called the key pool scheme and the key chain scheme, to solve this dilemma without any synchronization or periodic key redistribution. Both schemes utilize a Bloom filter and the distribution of secret keys among sensor nodes to create fast and capture-resistant PKC-based broadcast authentication protocols. Our NS-2 simulation results for a 3,000-node WSN confirm that broadcast delays of our protocol are only 46.7% and 39.4% slower than the forwarding-first scheme for the key pool and the key chain scheme respectively. At the same time, both protocols are an order of magnitude faster than the authentication-first scheme. The key pool scheme is able to keep forged message propagation to the minimal even when the majority of the nodes have been captured by the attacker. The key chain scheme has smaller transmission overhead than the key pool scheme at the expense of less resistance to node capturing. Two generic improvements to these schemes are also described. One reduces the marking limit on the Bloom filter vector (BFV), which makes it more difficult for an attacker to forge a BFV for a bogus message. The other limits broadcast forwarding to a spanning tree, which reduces the number of nodes forwarding bogus messages by one to two orders of magnitude depending on the percentage of compromised nodes. The first improvement can be applied to any BFV scheme, while the second is even more generally applicable. 相似文献
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Collaborative in-network processing operations in Wireless multimedia sensor networks (WMSNs) often require effective synchronization control. Extensive researches in the traditional networks mainly focus on the synchronization control with the buffer management in the receiver. However, for WMSNs, the chaotic transport channel and low bandwidth introduce serious jitter. Jitter degrades the timing relationship among packets in a single media stream and between packets from different media streams and, hence, creates multimedia synchronization problems. Moreover, too much jitter will also degrade the performance of the streaming buffer. By only employing the buffer management scheme in the receiver, we can hardly satisfy the synchronization requirement of the in-network processing. In this study, we propose an active jitter detection mechanism for the synchronization control in WMSNs. This mechanism will improve the quality of service in multimedia networking by discarding the jitter-corrupted packets immediately and balancing the delay and jitter actively. We implement the proposed scheme in the practical WMSNs platform. The experiment results show that our scheme can reduce the average packet jitter effectively and improve the synchronization controlling performance significantly. 相似文献