Distributed estimation for adaptive sensor selection in wireless sensor networks

Wireless sensor networks (WSNs) are usually deployed for monitoring systems with the distributed detection and estimation of sensors. Sensor selection in WSNs is considered for target tracking. A distributed estimation scenario is considered based on the extended information filter. A cost function using the geometrical dilution of precision measure is derived for active sensor selection. A consensus-based estimation method is proposed in this paper for heterogeneous WSNs with two types of sensors. The convergence properties of the proposed estimators are analyzed under time-varying inputs. Accordingly, a new adaptive sensor selection (ASS) algorithm is presented in which the number of active sensors is adaptively determined based on the absolute local innovations vector. Simulation results show that the tracking accuracy of the ASS is comparable to that of the other algorithms.     

A self-stabilizing algorithm for strong fairness

Self-stabilization is a novel technique to deal with faults in distributed systems. This paper presents a distributed self-stabilizing algorithm for implementing strong fairness in an arbitrary network. A desirable feature of this algorithm is that it can be used to enforce the strong fairness property on any distributed algorithm including self-stabilizing algorithms. In addition, the algorithm does not require any initialization and can withstand transient failures. At the end of the paper such issues as improving the time complexity of the proposed algorithm and the limitations on the efficiency of any implementation of strong fairness are discussed.     

基于时空特性的无线传感器网络节点故障诊断方法

无线传感器网络中故障节点会产生并传输错误数据,这将消耗节点的能量和带宽,同时会形成错误的决策。利用节点感知数据的空间相似性,提出了节点故障诊断的算法,通过对邻节点所感知的传感数据进行比较,从而确定检测节点的状态,并将测试状态向网络中其他相邻节点进行扩散。对于网络中存在的节点瞬时故障,通过时间冗余的检测方法,降低故障诊断的虚警率。该算法对实现故障节点的检测具有较好的性能,实验结果验证了算法的可行性和有效性。     

A self-stabilizing algorithm to synchronize digital clocks in a distributed system

We have proposed a self-stabilizing algorithm to synchronize multiple digital clocks in a distributed system; whenever any of the clock values gets out of synchronization for any reason, the algorithm is automatically invoked and the system is brought back to a legitimate state in finite time.     

无线传感器网络中基于Voronoi图的覆盖和连通综合配置协议

着重研究无线传感器网络随机部署下的覆盖和连通问题的解决方案,尤其是当无线传感器节点的通信半径Rc与感应半径Rs之比小于2时的解决方案.本文提出了无线传感器网络中一个基于Voronoi图的覆盖和连通的综合配置协议(VIP).该协议采用了一种分布式节点冗余判断算法以判断无线传感器网络中节点的冗余性,并让节点据此来对自身进行相应的职能调度.该协议能够在Rc/Rs为任意值时保证网络的覆盖和连通性能.本文还将该协议进行了推广,使得该协议能够满足覆盖度和连通度动态变化的要求,保证网络的k-度覆盖和k-度连通.     

A note on leader election in directed split-stars and directed alternating group graphs

A leader node is defined to be any node of the network unambiguously identified by some characteristics. In this paper, we first present a distributed algorithm for finding a leader node of a directed split-star. Moreover, an efficient self-stabilizing leader election algorithm that converges with linear rounds is proposed for directed split-stars. Actually, the distributed algorithm and the self-stabilizing algorithm are also applicable to the problem of directed alternating group graphs. As far as we know, no self-stabilizing leader election algorithm was known for the two graphs.     

一种无线传感器网络定位算法的分析和改进

无线传感器网络(W SNs)能够实时监测和采集网络分布区域内的各种检测对象信息,有着广泛的应用前景。在W SNs中,节点定位技术是许多应用的支撑技术,定位的准确性直接关系到传感器节点采集数据的有效性。目前,已提出多种定位算法,Euc lidean算法由于通信开销小,具有一定的优越性,但在某些应用中存在定位精度较低的问题。针对这一问题,提出了一种新的改进Euc lidean的算法。用距离矢量路由技术替代直接测量节点间的距离,并运用迭代循环思想抑制定位误差的累计。计算机仿真结果证明:该改进算法能够明显地提高定位精度。     

Local Stabilizer

A local stabilizer protocol that takes any on- or off-line distributed algorithm and converts it into a synchronous self-stabilizing algorithm with local monitoring and repairing properties is presented. Whenever the self-stabilizing version enters an inconsistent state, the inconsistency is detected, in O(1) time, and the system state is repaired in a local manner. The expected computation time that is lost during the repair process is proportional to the largest diameter of a faulty region.     

无线传感器网络网内数据融合的研究

针对目前无线传感器网络(WSNs)网内数据融合所面临的一些挑战,提出了一种基于无线传感器网络分布式K-平均聚类(DKCWSNs)算法的WSNs节点传感数据的分组策略,并采用基于自适应加权的数据融合方法对分组后的感知数据进行融合处理,从而获得更合理的结果.最后,通过实例验证了该方法的有效性.     

Uniform and self-stabilizing token rings allowing unfair daemon

A distributed system consists of a set of processes and a set of communication links, each connecting a pair of processes. A distributed system is said to be self-stabilizing if it converges to a correct system state no matter which system state it starts with. A self-stabilizing system is considered to be an ideal fault tolerant system, since it tolerates any kind and any finite number of transient failures. In this paper, we investigate uniform randomized self-stabilizing mutual exclusion systems on unidirectional rings. As far as deterministic systems are concerned, it is well-known that there is no such system when the number 6 of processes (i.e., ring size) is composite, even if a fair central-daemon (c-daemon) is assumed. A fair daemon guarantees that every process will be selected for activation infinitely many times. As for randomized systems, regardless of the ring size, we can design a self-stabilizing system even for a distributed-daemon (d-daemon). However, every system proposed so far assumes a daemon to be fair, and effectively replies on this assumption. This paper tackles the problem of designing a self-stabilizing system, without assuming the fairness of a daemon. As a result, we present a randomized self-stabilizing mutual exclusion system for any size n (including composite size) of a unidirectional ring. The number of process states of the system is 2(n-1)     

基于CPCRLB和一致性算法的分散式传感器管理

针对无线传感器网络中的目标跟踪问题,基于条件后验克拉美—罗下界（CPCRLB）提出一种分散式传感器节点管理方法．基于一致性策略给出一种CPCRLB的分布式迭代算法,并且基于分布式粒子滤波器给出该算法的数值逼近实现．对层次结构的无线传感器网络,将CPCRLB作为传感器管理的准则,基于平均一致性给出一种迭代的局部搜索算法,实现了无线传感器网络下观测节点的分散式在线选择．仿真结果表明了基于CPCRLB的分散式传感器管理方法在目标跟踪精度方面的有效性．     

WSNs中数据融合树的时隙分配算法

周期工作DC(Duty-Cycling)技术,即周期地开/关通信和感测能力,能够有效降低传感节点的活动时间,进而延长无线传感网络寿命.然而,此技术给数据融合提出了挑战.为此,提出免碰撞的数据融合树的时隙分配算法CF-DGSS(Collision-Free Data Aggregation Slots Scheduling Algorithm for Duty-Cycled Wireless Sensor Networks),进而解决基于DC的WSNs的数据融合时隙分配问题.为了解决碰撞问题,CF-DGSS算法给每个节点构建冲突集.每个节点在融合时隙分配过程中,保存自己的冲突集.在分配时隙时,传感节点应当确保与冲突集内节点的数据融合不干扰.仿真结果表明,与其他的分配算法相比,提出的CF-DGSS算法具有低的融合时延.     

一种适合Underlay认知无线传感网络的跨层路由算法

在Underlay认知无线传感网络（Underlay Cognitive Radio Sensor Network,Underlay CRSN）中,由于每个信道被主用户所使用的状态随机变化,设计路由算法不仅需要考虑网络中节点的能量消耗以及延长网络寿命的需求,还要考虑路由路径上各链路的信道选择策略对路径数据传输可靠性的影响。该文研究了Underlay认知无线电模型下的CRSN路由问题,提出了一种适合该路由问题的链路Utility函数,并将这类问题建模为以最小化Utility为目标的最优化问题。在讨论了几种传统的无线传感器网络（Wireless Sensor Network,WSN）路由算法之后,提出了一种适合Underlay CRSN的跨层路由算法,并给出了该算法的分布式实现方案。计算机仿真表明所提出的路由算法能很好地适应UnderlayCRSN中信道可用状态的随机变化。     

基于分布式图算法的无线网络MAC调度算法

针对无线自组织网络带宽利用率低的问题,在主干扰模型的基础上,提出一种基于分布式极大独立集(MIS)的无线自组织网络STDMA节点调度算法.该算法以分布式MIS算法为基础,在算法进入平衡状态时,优先让度大的节点加入MIS,再通过将其结果转化成△+1染色,从而完成时槽分配.该算法是完全分布式的,且时间复杂度为O(1bn).仿真结果表明,与分布式MIS算法相比,该算法收敛速度平均提高23.6％.     

A 4n-move self-stabilizing algorithm for the minimal dominating set problem using an unfair distributed daemon

A distributed system is self-stabilizing if, regardless of its initial state, the system is guaranteed to reach a legitimate (i.e., correct) state in finite time. In 2007, Turau proposed the first linear-time self-stabilizing algorithm for the minimal dominating set (MDS) problem under an unfair distributed daemon [9]; this algorithm stabilizes in at most 9n moves, where n is the number of nodes in the system. In 2008, Goddard et al. [4] proposed a 5n-move algorithm. In this paper, we present a 4n-move algorithm.     

Range-Free Localization Using Expected Hop Progress in Wireless Sensor Networks

Localization algorithm continues to be an important and challenging topic in today's wireless sensor networks (WSNs). In this paper, a novel range-free localization algorithm using expected hop progress (LAEP) to predict the location of any sensor in a WSN is proposed. This algorithm is based on an accurate analysis of hop progress in a WSN with randomly deployed sensors and arbitrary node density. By deriving the expected hop progress from a network model for WSNs in terms of network parameters, the distance between any pair of sensors can be accurately computed. Since the distance estimation is a key issue in localization systems for WSNs, the proposed range-free LAEP achieves better performance and less communication overhead as compared to some existent schemes like DV-Hop and RAW. In addition, we study the effect of anchor placement on the algorithm performance by deriving the corresponding mean position error range. Extensive simulations are performed and the results are observed to be in good agreement with the theoretical analysis.     

Uniform dynamic self-stabilizing leader election

A distributed system is self-stabilizing if it can be started in any possible global state. Once started the system regains its consistency by itself, without any kind of outside intervention. The self-stabilization property makes the system tolerant to faults in which processors exhibit a faulty behavior for a while and then recover spontaneously in an arbitrary state. When the intermediate period in between one recovery and the next faulty period is long enough, the system stabilizes. A distributed system is uniform if all processors with the same number of neighbors are identical. A distributed system is dynamic if it can tolerate addition or deletion of processors and links without reinitialization. In this work, we study uniform dynamic self-stabilizing protocols for leader election under readwrite atomicity. Our protocols use randomization to break symmetry. The leader election protocol stabilizes in O(ΔD log n) time when the number of the processors is unknown and O(ΔD), otherwise. Here Δ denotes the maximal degree of a node, D denotes the diameter of the graph and n denotes the number of processors in the graph. We introduce self-stabilizing protocols for synchronization that are used as building blocks by the leader-election algorithm. We conclude this work by presenting a simple, uniform, self-stabilizing ranking protocol     

Symbolic model checking for self-stabilizing algorithms

A distributed system is said to be self-stabilizing if it converges to safe states regardless of its initial state. In this paper we present our results of using symbolic model checking to verify distributed algorithms against the self-stabilizing property. In general, the most difficult problem with model checking is state explosion; it is especially serious in verifying the self-stabilizing property, since it requires the examination of all possible initial states. So far applying model checking to self-stabilizing algorithms has not been successful due to the problem of state explosion. In order to overcome this difficulty, we propose to use symbolic model checking for this purpose. Symbolic model checking is a verification method which uses Ordered Binary Decision Diagrams (OBDDs) to compactly represent state spaces. Unlike other model checking techniques, this method has the advantage that most of its computations do not depend on the initial states. We show how to verify the correctness of algorithms by means of SMV, a well-known symbolic model checker. By applying the proposed approach to several algorithms in the literature, we demonstrate empirically that the state spaces of self-stabilizing algorithms can be represented by OBDDs very efficiently. Through these case studies, we also demonstrate the usefulness of the proposed approach in detecting errors     

一种改进的DFD无线传感器网络节点故障诊断算法研究

无线传感器网络是远程分布式环境监测的重要手段。节点故障诊断作为无线传感器网络的关键技术之一,是无线传感器网络大多应用领域不可或缺的环节。DFD算法是一种可应用于无线传感器网络的节点故障诊断算法,通过网络内邻居节点间的数据交换和相互测试诊断出故障节点。对DFD算法的诊断判据进行了修改,提出了改进的DFD算法。仿真结果表明,改进的DFD算法能适用于待诊断节点的邻居节点数较少、节点故障率较高的传感器网络,且大大提高了故障诊断精度。