Mobility-assisted minimum connected cover in a wireless sensor network

All properties of mobile wireless sensor networks (MWSNs) are inherited from static wireless sensor networks (WSNs) and meanwhile have their own uniqueness and node mobility. Sensor nodes in these networks monitor different regions of an area of interest and collectively present a global overview of monitored activities. Since failure of a sensor node leads to loss of connectivity, it may cause a partitioning of the network. Adding mobility to WSNs can significantly increase the capability of the WSN by making it resilient to failures, reactive to events, and able to support disparate missions with a common set of sensor nodes. In this paper, we propose a new algorithm based on the divide-and-conquer approach, in which the whole region is divided into sub-regions and in each sub-region the minimum connected sensor cover set is selected through energy-aware selection method. Also, we propose a new technique for mobility assisted minimum connected sensor cover considering the network energy. We provide performance metrics to analyze the performance of our approach and the simulation results clearly indicate the benefits of our new approach in terms of energy consumption, communication complexity, and number of active nodes over existing algorithms.     

无线传感器网络分簇路由节能研究

在大规模传感和环境监测中,节约能源延长传感器节点生命已成为无线传感器网络最重要的研究课题之一。提供合理的能源消耗和改善无线网络生命周期的传感器网络系统,必须设计一种新的有效的节能方案和节能路由体系。方案采用一种聚类算法减少无线传感器网络的能量消耗,创建一种cluster-tree分簇路由结构的传感器网络。该方案主要目标是做一个理想的分簇分配,减少传感器节点之间的数据传输距离,降低传感器节点能源消耗,延长寿命。实验结果表明,该方案有效地降低了能源消耗从而延长无线传感器网络生命。     

一种基于能耗均衡的分区节点部署算法

鉴于能耗问题是无线传感器网络研究的重要问题, 首先建立一种非均匀部署网络拓扑模型, 该模型中越靠近sink 的区域节点部署越密集, 节点通信距离越小; 然后针对节点初始随机部署情况, 提出一种基于节点能耗均衡的分区域节点重部署算法, 该算法利用分区域的节点移动, 减少节点移动距离, 降低移动能耗, 提高算法收敛速度; 最后通过仿真表明, 所提出的算法可以用较少数量的节点覆盖监测区域, 保证网络中各节点能量均衡消耗, 提高网络生存周期.

     

LABS: Latency aware broadcast scheduling in uncoordinated Duty-Cycled Wireless Sensor Networks

Broadcast is a fundamental operation in Wireless Sensor Networks (WSNs) and plays an important role in a communication protocol design. In duty-cycled scenarios, a sensor node can receive a message only in its active time slot, which makes it more difficult to design collision-free scheduling for broadcast operations. Recent studies in this area have focused on minimizing broadcast latency and guaranteeing that all nodes receive a broadcast message. This paper investigates the problem of Minimum Latency Broadcast Scheduling in Duty-Cycled (MLBSDC) WSNs. By using special geometric properties of independent sets of a broadcast tree, we reduce the number of transmissions, consequently reducing the possibility of collision. Allowing multiple transmissions in one working period, our proposed Latency Aware Broadcast Scheduling (LABS) scheme provides a latency-efficient broadcast schedule. Theoretical analysis proves that the scheme has the same approximation ratio and complexity as the previous best algorithm for the MLBSDC problem. Moreover, simulation shows that the new scheme achieves up to 34%, 37%, and 21% performance improvement over previous schemes, in terms of latency, number of transmissions, and energy consumption, respectively.     

一种无线传感器网络目标的最优覆盖算法

无线传感器网络点状目标覆盖的算法中,集合分割算法虽简单,但效率低且仅适用于每个传感器节点能量都相等的网络模型.为此,我们对集合分割算法进行改进,提出一种启发式贪心最优覆盖算法.该算法适用于节点能量正态分布的网络模型,采用了关键目标优先覆盖策略和节点能效最大化策略,延长了网络覆盖生命期,提高了算法的效率.实验表明新算法网络生命期延长80%以上,有更好的适应性和稳定性.     

基于元胞蚁群优化算法的农业无线传感器网络路由研究

无线传感器网络(WSNs)进行农业信息采集时,针对传感器节点数量多,能量消耗不均衡的特点,提出基于元胞蚁群优化(CACO)的WSNs路由算法。算法将网络中的节点映射成CACO算法中的元胞,通过改进蚂蚁信息素更新模型,引入睡眠唤醒机制,有效地减少了节点间的通信,从而改善能量消耗不均衡。仿真结果表明:该算法有效地减少了网络耗能、节点消亡数量,延长了网络生命期。     

一种抗干扰半静态分簇路由算法

针对无线传感器网络( WSNs)分簇路由算法中的能量洞、热点和抗干扰问题,设计一种抗干扰半静态分簇( AlSSC)路由算法,给无线传感器网络提供能量多、距离短、链路质量好的路径来传输数据.该算法利用节点定位获取节点地理位置,综合考虑传感器节点剩余能量和干扰信噪比,通过节点距离度量、节点聚簇、簇间融合、簇头选举和簇头轮换五个步骤进行无线传感器网络节点的分簇.仿真结果表明:这种路由算法可以提高无线传感器网络通信链路质量,均衡网络能量消耗.     

无线传感器网络中基于关联度的多查询优化

无线传感器网络是一种以数据为中心的网络,用户通过基站向网络提出查询请求获取所需数据。如何通过多查询的优化来减少传感器节点的能耗以延长网络生命期是无线传感器网络中需要解决的关键问题之一。提出了基于关联度的多查询优化算法,其基本思想是节点通过节点与候选父亲节点之间的关联度来选择父节点,从而被相同查询覆盖的节点聚集成一个组,多个查询间共享组中节点的数据,在网络中对查询数据进行有效的融合,充分减少了网络的数据传输量,延长了网络的生命期。理论分析和模拟实验表明该算法可以充分减少数据传输量,从而达到节能的目的。     

一种基于时间延迟机制的WSNs非均匀分簇算法

为减少无线传感器网络分簇路由协议中节点竞争簇首时多余的能耗,解决簇首能耗不均的问题,提出一种基于时间延迟机制的非均匀分簇算法。该算法使能量较多的节点被优先选为簇首,并提出了簇首竞争半径的计算方法,确保其数目稳定且位置均匀分布。成簇过程中,节点根据最小消费函数选择簇首,簇内成员加入时考虑簇首能量、二者距离以及簇首和汇聚节点角度等因素来均衡簇首能耗。仿真结果表明:算法能有效地均衡节点能耗,延长网络寿命,分别比CHTD和EEUC算法延长了35.1%和12.9%。     

面向异构WSNs的基于能量感知的簇路由算法

有效地使用传感节点的能量,进而延长网络寿命成为设计无线传感网路由协议的一项挑战性的工作.为了延长网络,现存的多数簇路由是面向同构网络.为此,提出分布式能量感知的异构WSNs非均匀分簇路由DEAC(Distributed Energy Aware unequal Clustering)算法.DEAC算法是以EADUC(Energy Aware Distributed Unequal Clustering)为基础,并进行优化.与EADUC不同,DEAC算法从簇头竞选机制、簇间多跳通信中的下一跳转发节点的选择策略以及自适应的节点通信半径的设置三方面进行优化.在簇头竞选机制中,采用退避算法,利用节点的剩余能量以及邻居节点的平均能量设置延时时间;在选择下一跳转发节点时,建立节点的关于能量的度量函数,选择具有最大剩余能量的节点作为下一跳;而在设置节点通信半径时,考虑了距离、剩余能量以及邻居节点数信息.仿真结果表明,与EADUC协议相比,提出的DEAC算法能够有效地延缓第1个节点失效的时间,减少了能耗,扩延网络寿命.     

一种基于多播分发树的无线传感器网络代码分发协议

代码分发协议是无线传感器网络（WSNs）在实地部署之后进行软件更新的关键技术。针对现有代码分发协议对特定目标节点分发时需要传输冗余代码镜像的问题,提出了一种基于多播分发树的代码分发（MTCD）协议。MTCD协议通过建立基站节点到目标节点的分发树路径来降低网络中参与代码分发节点的个数,从而降低数据冗余传输和网络能量消耗。TOSSIM仿真结果表明：与TinyOS的标准代码分发协议Deluge相比,MTCD协议在分发时间和数据包传输方面都有更优的性能。     

A novel gossip-based sensing coverage algorithm for dense wireless sensor networks

Wireless sensor networks (WSNs) have been widely studied and usefully employed in many applications such as monitoring environments and embedded systems. WSNs consist of many nodes spread randomly over a wide area; therefore, the sensing regions of different nodes may overlap partially. This is called the “sensing coverage problem”. In this paper, we define a maximum sensing coverage region (MSCR) problem and present a novel gossip-based sensing-coverage-aware algorithm to solve the problem. In the algorithm, sensor nodes gossip with their neighbors about their sensing coverage region. In this way, nodes decide locally to forward packets (as an active node) or to disregard packets (as a sleeping or redundant node). Being sensing-coverage-aware, the redundant node can cut back on its activities whenever its sensing region is k-covered by enough neighbors. With the distributed and low-overhead traffic benefits of gossip, we spread energy consumption to different sensor nodes, achieve maximum sensing coverage with minimal energy consumption in each individual sensor node, and prolong the whole network lifetime. We apply our algorithm to improve LEACH, a clustering routing protocol for WSNs, and develop a simulation to evaluate the performance of the algorithm.     

无线传感器网络分簇拓扑控制算法

通过对经典的分簇算法HEED和EEUC进行研究与分析,对它们不足之处进行了改进,提出了一种新的基于双簇首节能的无线传感器网络分簇拓扑控制算法,即DCHEB算法。该算法提出了一种新的簇划分方案,通过此方案可以对无线传感器网络进行合理分簇,使得簇首节点位于合适的位置上,平均了各个簇的节点个数,可以避免簇内的边缘节点过早死亡。最后通过理论分析和仿真工具验证了该算法对减少无线传感器网络的能量消耗和延长其生存时间有很好的作用。     

Recovery from multiple simultaneous failures in wireless sensor networks using minimum Steiner tree

In some applications, wireless sensor networks (WSNs) operate in very harsh environments and nodes become subject to increased risk of damage. Sometimes a WSN suffers from the simultaneous failure of multiple sensors and gets partitioned into disjoint segments. Restoring network connectivity in such a case is crucial in order to avoid negative effects on the application. Given that WSNs often operate unattended in remote areas, the recovery should be autonomous. This paper promotes an effective strategy for restoring the connectivity among these segments by populating the least number of relay nodes. Finding the optimal count and position of relay nodes is NP-hard and heuristics are thus pursued. We propose a Distributed algorithm for Optimized Relay node placement using Minimum Steiner tree (DORMS). Since in autonomously operating WSNs it is infeasible to perform a network-wide analysis to diagnose where segments are located, DORMS moves relay nodes from each segment toward the center of the deployment area. As soon as those relays become in range of each other, the partitioned segments resume operation. DORMS further model such initial inter-segment topology as Steiner tree in order to minimize the count of required relays. Disengaged relays can return to their respective segments to resume their pre-failure duties. We analyze DORMS mathematically and explain the beneficial aspects of the resulting topology with respect to connectivity, and traffic balance. The performance of DORMS is validated through extensive simulation experiments.     

混合WSNs中基于多目标优化的覆盖控制算法

针对无线传感器网络( WSNs)随机部署产生的区域覆盖率低、节点利用率差和能量不均衡的问题,引入移动传感器节点,将快速非支配排序遗传算法Ⅱ( NSGA-Ⅱ)运用到混合无线传感器网络覆盖控制部署并进行改进,采用分层编码策略,引入删除算子避免早熟,自适应改变交叉、变异概率提高局部搜索能力,获得较优解集后基于决策者信息偏好选择最优目标.仿真实验结果表明:有效解决了WSNs覆盖控制问题,可以在网络覆盖率最大化的同时,节点利用率较大且能耗系数较低,延长网络寿命.     

一种无线传感器网络MAC协议优化算法

在无线传感器网络中,各节点采集的信息以多跳的方式传送到汇聚点.从各节点到汇聚点形成一棵以汇聚点为根的传输树.文中在对无线传感器网络传输特点分析的基础上,剖析了基于CSMA/CA(载波多路监听/冲突避免)的MAC协议在树状结构无线传感器网络中的弊端,提出了一种基于CSMA/CA的MAC协议优化算法.算法基于节点在传输树中的位置信息调整其MAC信道接入分配,将CSMA/CA采用的各节点均等竞争信道的方法优化为各节点依据在传输树中的位置情况竞争信道的方式,这一优化提高了节点公平性,使MAC信道接入分配与树状结构的无线传感器网络传输特点相契合,解决了基于CSMA/CA的MAC协议与树状结构无线传感器网络不匹配的问题,从而减少了信道资源浪费,提高了网络传输效率,降低了能耗.实验结果表明该算法在网络丢包率、吞吐量和能耗方面的性能均有较大改进.     

无线传感器网络中多Sink节点位置部署研究

通过对随机分布的无线传感器网络节点密度和能量消耗的关系的分析,提出了无线传感器网络中多异构节点位置部署的区域密度优先(RDF)算法。此算法采用密度优先原则来决定Sink节点的放置位置,通过栅格和异构节点通信范围对网络进行区域划分。该算法比递归算法的异构节点放置位置优越,虽然在网络寿命上相接近,但远大于随机分布策略的寿命,且RDF更适合实际应用。通过仿真验证:该算法能够有效延长网络寿命和快速实现部署。     

单节点的无线传感器网络数据传输优化策略

为了提高无线传感器网络（WSNs）节点能量的利用率,延长WSNs的生存时间,提出了一种单节点的WSNs数据传输优化策略.首先对WSNs结构进行分析,并建立单个传感器节点数据传输优化的数学模型;然后采用惩罚函数法对数据传输过程中的传感器节点能耗进行优化;最后在Matlab 2012平台对其进行仿真分析.结果表明：该方法可以根据环境能量的变化对传感器节点能耗进行自适应优化,提高了节点的累积数据传输总量,可以较好适应环境能量不确定性.     

一种能量高效的无线传感器网络拓扑控制算法

通过对现有拓扑控制算法的研究,针对无线传感器网络中节点能耗分布不均匀的问题,提出了一种能量高效的拓扑控制算法(EETCA)。该算法以均衡全局能耗为目标,综合考虑了节点的剩余能量、簇的规模、数据最优传输跳数等因素,避免了部分节点能量消耗过快,从而有效地均衡网络负载。仿真结果表明:EETCA在能耗均衡方面均优于原来的算法,延长了无线传感器网络的生命周期。     

一种新的删除AVL树的结点的算法

所有传统的删除AVL树的结点的算法的主要思想都是先删除结点再自下而上处理某些子树,涉及自下而上的后退。提出一种新的删除AVL树的结点的算法,其主要思想是先自上而下处理某些子树再删除结点,不涉及自下而上的后退。举例说明新算法的执行过程。证明新算法是正确的。与目前通常采用的Foster的算法相比,新算法不涉及辅助栈的使用。设n是AVL树的结点的个数。新算法的时间复杂性是O(log2n),与Foster的算法相同。实验结果表明新算法的平均执行时间比Foster的算法的短。新算法的空间复杂性是O(1),比Foster的算法的低。