Multiround Distributed Lifetime Coverage Optimization protocol in wireless sensor networks

Coverage and lifetime are two paramount problems in wireless sensor networks (WSNs). In this paper, a method called Multiround Distributed Lifetime Coverage Optimization protocol (MuDiLCO) is proposed to maintain the coverage and to improve the lifetime in wireless sensor networks. The area of interest is first divided into subregions, and then the MuDiLCO protocol is distributed to the sensor nodes in each subregion. The proposed MuDiLCO protocol works in periods during which sets of sensor nodes are scheduled, with one set for each round of a period, to remain active during the sensing phase and thus ensure coverage so as to maximize the WSN lifetime. The decision process is carried out by a leader node, which solves an optimization problem to produce the best representative sets to be used during the rounds of the sensing phase. The optimization problem formulated as an integer program is solved to optimality through a Branch-and-Bound method for small instances. For larger instances, the best feasible solution found by the solver after a given time limit threshold is considered. Compared with some existing protocols, simulation results based on multiple criteria (energy consumption, coverage ratio, and so on) show that the proposed protocol can prolong efficiently the network lifetime and improve the coverage performance.     

A novel energy-efficient clustering protocol with area coverage awareness for wireless sensor networks

Coverage is a key metric in evaluating the monitoring capacity and quality of services in wireless sensor networks. The energy consumption of self-contained sensors is also a challenging problem for energy-efficient use while still achieving better coverage performance. Although techniques have been developed to mitigate the problem of area coverage, particularly together with efficient clustering methods, none focuses intensively on the sensor activation stage, which is used to maintain coverage while optimizing energy usage. In this research, we thus propose a cover set to find the minimum set of sensors that completely cover the sensing ranges within an interest area as a criterion for sensor activation. Our main goal is to select an optimal number of active sensors considering residual energy and the cover set and to keep alive the important sensors for the sensing coverage task as long as possible. Additionally, this research proposes an area coverage-aware clustering protocol (ACACP) with energy consumption optimization with respect to the activation sensor, network clustering, and multi-hop communication to improve overall network lifetime while preserving coverage. Throughout the intensive simulation, given a diversity of deployments with scalability concern, the results demonstrate the effectiveness of ACACP when compared with other competitive approaches such as ECDC and DECAR, including state-of-the-art clustering protocols such as LEACH, in terms of coverage ratio and overall network lifetime.     

概率模型下的一种优化覆盖算法

覆盖率不仅是评价无线传感器网络体系性能的重要标准之一,也是无线传感器网络所研究的一项重点课题.为此,提出了一种概率模型下优化覆盖算法.该算法通过对概率覆盖模型的计算,给出了传感器节点覆盖的期望值和公差的求解过程以及对所关注目标节点进行首次覆盖后的期望值证明过程.在网络能量方面则通过节点状态调度策略对通信路径进行优化,证明节点能量衰减过程中,拟合函数极限存在的意义,实现了传感器节点能量的有效匹配,抑制了传感器节点能量的消耗,证明了优化后整个监测区域传感器节点覆盖函数之间的关系.仿真实验结果表明,该算法不仅提高了覆盖和网络服务质量,而且有效地抑制了网络能量开销,延长了网络生存周期.     

基于Voronoi图的无线传感器网络K覆盖算法

针对无线传感器网络(WSN)在随机高密度部署节点情况下的多重覆盖问题,提出一个基于Voronoi图的K覆盖算法。该算法利用邻居节点信息计算Voronoi覆盖邻居节点集,构建有向Voronoi覆盖关系图,通过调整关系图中的节点状态实现K覆盖。仿真结果表明,该算法能正确判断网络覆盖率,连通K覆盖的近似最小活动节点集数目少于CCP算法。     

C3: an energy-efficient protocol for coverage,connectivity and communication in WSNs

The lower layer of ubiquitous and pervasive systems consists of wireless ad hoc and sensor networks. In wireless sensor networks (WSNs), sensors consume most of their energy in data transmission and idle listening. Hence, efficient usage of energy can be ensured by improved protocols for topology control (i.e., coverage and connectivity), sleep scheduling, communication, and aggregation and compression of data. Though several protocols have been proposed for this purpose, they are not energy-efficient. We propose an integrated and energy-efficient protocol for Coverage, Connectivity, and Communication (C3) in WSNs. The C3 protocol uses received signal strength indicator to divide the network into virtual rings, defines clusters with clusterheads more probably at alternating rings, defines dings that are rings inside a cluster and uses triangular tessellation to identify redundant nodes, and communicates data to sink through clusterheads and gateways. The proposed protocol strives for near-optimal deployment, load balancing, and energy-efficient communication. Simulation results show that the C3 protocol ensures partial coverage of more than 90 % of the total deployment area, ensures one connected network, and facilitates energy-efficient communication while expending only one-fourth of the energy compared to other related protocols such as the coverage and connectivity protocol, and the layered diffusion-based coverage control.     

一种能量有效的无线传感器网络覆盖控制算法

覆盖问题是WSN(无线传感器网络)的基本问题,合理的覆盖控制可以有效地延长WSN的生存时间.提出一种能量有效的WSN覆盖控制算法(EECCA).算法中,节点采用布尔感知模型,节点根据自己的能量大小和连续未当选工作节点的轮数,来触发定时器进行工作节点选择,并根据邻居节点的能量信息进行了工作节点优化.仿真实验结果表明,算法不仅可以满足覆盖率要求,而且在减少总体能量消耗方面也有很好的改善.     

面向异构网络的基于 k-覆盖的休眠调度算法

异构无线传感网络WSNs(Wireless Sensor Networks)的多数监测应用要求兴趣区域FoI(Field of Interest)是k覆盖(k-cover),且k≥1.而冗余节点被安排为休眠,进而最小化能量消耗.为此,提出面向异构网络的基于k-覆盖的冗余节点休眠算法k-CRSS(k-cover based sleep Scheduling algorithm for redundant node).k-CRSS算法引用概率方法判断节点是否为冗余节点,并推导判断一个节点是否为冗余节点的概率表述式.然后,引用调度算法识别所有冗余节点,并让它们进行休眠,且在FoI内不出现覆盖空洞.k-CRSS算法属分布式算法,并无需任何地理信息,仅通过少量控制消息收集邻居节点信息.实验数据表明,k-CRSS算法通过调度算法减少了活动节点数,进而延长了网络寿命.     

Connectivity preserving localized coverage algorithm for area monitoring using wireless sensor networks

Efficient network coverage and connectivity are the requisites for most Wireless Sensor Network (WSN) deployments, particularly those concerned with area monitoring. Due to the resource constraints of the sensor nodes, redundancy of coverage area must be reduced for effective utilization of the available resources. If two nodes have the same coverage area in their active state, and if both the nodes are activated simultaneously, it leads to redundancy in network and wastage of precious sensor resources. In this paper, we address the problem of network coverage and connectivity and propose an efficient solution to maintain coverage, while preserving the connectivity of the network. The proposed solution aims to cover the area of interest (AOI), while minimizing the count of the active sensor nodes. The overlap region of two sensor nodes varies with the distance between the nodes. If the distance between two sensor nodes is maximized, the overall coverage area of these nodes will also be maximized. Also, to preserve the connectivity of the network, each sensor node must be in the communication range of at least one other node. Results of simulation of the proposed solution indicate up to 95% coverage of the area, while consuming very less energy of 9.44 J per unit time in the network, simulated in an area of 2500 m².     

基于能量和邻居信息的传感器睡眠调度协议

调度冗余节点轮流工作能够有效延长网络寿命。研究传感器网络节点的随机睡眠调度机制,给出了一种基于能量和节点邻居距离的随机调度机制。传感器节点根据自身的能量大小以及邻居的信息确定睡眠概率,使能量较小,并且工作邻居节点数目大的节点获得较大的睡眠概率。最后分析比较了这种机制与另外两种机制的性能。实验结果表明,基于能量和邻居信息的调度机制能够减少工作节点个数,保证较高的网络覆盖率。     

基于活动区域的移动无线传感器网络路由协议

为了解决移动无线传感器网络中能量效率问题,提出了一种基于活动区域的移动无线传感器网络（WSN）路由协议。本方法使用源和sink节点相对位置来形成路由的活动区域,网络中的移动节点使用睡眠唤醒模式来节约能源。移动向量信息（如当前位置、方向和速度）以及节点的剩余能量,用于选择能够提供最大连接保留时间的邻居,移动向量信息也被用来唤醒活动区域中的移动节点。实验表明,与其他路由协议进行比较,该方法在分组传输过程中具有更高的可靠性。     

无线传感器网络中能耗均衡的覆盖控制算法

覆盖控制作为无线传感器网络的一个基本问题,对网络的生存时间、部署策略、通信协议和组网等问题的解决具有重要影响。在传感器节点随机冗余部署方式下,传统的方式 是在保证覆盖要求和通信连通的前提下仅将最少量的节点投入活跃工作状态,从而降低网络能耗。但是,若频繁地激活同一批节点,会造成这些节点由于能耗过快而较早失效效,使整个网络的冗余程度降低。然而,冗余度是传感器网络在单个节点性能有限的情况下提高整个网络的可靠性、容错性、精确性等的基础。为此,本文提出了一个能耗均衡ECB的覆盖问题,指出它是NP完全的,并给出了一个集中式近似算法。该算法根据节点的剩余能量赋于每个节点非负权,再基于Voronoi划分和贪心边方法,在保证覆盖要求的同时选择权和最小的节点激活。仿真实验结果表明,ECB算法求得的活跃节点集小,可以达到有效覆盖,并且可以保持网络的冗余度。     

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.     

On the use of limited autonomous mobility for dynamic coverage maintenance in sensor networks

Sensor networks consist of small wireless sensor nodes deployed randomly over an area to monitor the environment or detect intrusion. The coverage provided by sensor networks is very crucial to their effectiveness. Many of the important applications of sensor networks demand autonomous mobility for the sensor nodes. Early failure of sensor nodes can lead to coverage loss that requires coverage maintenance schemes. In this paper, we propose Dynamic Coverage Maintenance (DCM) schemes that exploit the limited mobility of the sensor nodes. The main objective of coverage maintenance is to compensate the loss of coverage with minimum expenditure of energy. Existing autonomous sensor deployment schemes such as the “potential field approach” are not useful for DCM because the nodes initially distribute themselves such that there is no redundancy in coverage. We propose a set of DCM schemes which can be executed on individual sensor nodes having a knowledge of only their local neighborhood topology. The process of moving a node to a new location for maintenance of coverage is termed “migration”. We propose four algorithms to decide which neighbors to migrate, and to what distance, such that the energy expended is minimized and the coverage obtained for a given number of live nodes is maximized. The decision and movement are completely autonomous in the network, and involves movement of one-hop neighbors of a dead sensor node. We also propose an extension to these algorithms, called Cascaded DCM, which extends the migrations to multiple hops. We have developed a graphical simulator Java Sensor Simulator (JSS) to visually inspect the working of the algorithms. We have also compared the performance of the different algorithms in terms of the improvement in coverage, average migration distance of the nodes, and the lifetime of the network. Cascaded DCM was seen to offer the maximum network lifetime and coverage.     

基于无线传感器网络的手持终端设计

以油罐区的安全防治为背景,设计开发出一种便携式的基于无线传感器网络的手持终端设备,用以实现对油罐区各储油罐的实时信息监控.手持终端以CC2530作为主控芯片,在ZigBee协议栈Z-Stack的基础上设计程序,和分布在油罐区的采集节点共同组建了ZigBee无线传感器网络,使用者可以搜索并选择无线传感网络中存在的节点,实时查看该节点的温湿度、可燃气体浓度等与火灾相关的参数信息.文章提供了手持终端的硬件组成模块和电路原理图,并结合功能需要给出软件设计方案.     

ECDC: An energy and coverage-aware distributed clustering protocol for wireless sensor networks

Clustering for wireless sensor networks (WSNs) is an effective scheme in utilizing sensor nodes energy and extending the network lifetime, while coverage preservation is one of the most essential issues to guarantee the quality of service (QoS). However, the coverage problem has not been well understood so far. For mission-critical applications of networks, it is crucial to consider coverage requirements when we select cluster heads and routing nodes for the clustering topology. In this paper, we propose the ECDC (Energy and Coverage-aware Distributed Clustering Protocol), an integrated protocol involving both energy and coverage, which is different from previous clustering protocols. For different practical applications, we design corresponding coverage importance metrics and introduce them into the clustering algorithm. Theoretical analysis and simulation results show that our protocol is effective in improving network coverage performance, reducing nodes energy dissipation and extending the network lifetime.     

基于Memetic算法的WSN分簇协议的研究 *

针对无线传感器网络的寿命和覆盖优化,提出了一种基于Memetic算法和节点休眠-唤醒调度策略的复合文化基因聚类协议(Composite Memetic Algorithm Clustering Protocol,CMACP)。算法首先运行文化基因算法初始化需要激活的节点并规划相邻冗余节点,其中遗传算法和局部搜索算法能保障得到最优的初始节点分布。随着网络的运行,当某个节点因能量耗尽而丢失覆盖目标时,休眠调度策略选择激活最优相邻节点弥补覆盖漏洞。仿真实验表明,与其他WSN分簇协议相比,CMACP能较好的延长WSN稳定周期生存时间,并且提高WSN对感知区域的覆盖能力。     

无线传感器网络随机分布模型及覆盖控制研究

节点部署和覆盖控制是无线传感器网络中的一个基本问题,在传感器节点随机、高密度部署的环境中,通过数学模型和仿真实验证明了节点分布符合泊松分布特点,并且量化了部署节点感知半径、密度与面积覆盖率、k重覆盖的关系,以及覆盖控制模型中,在保证节点对监测区域有效覆盖前提下,近似取得需要休眠节点数量,为传感器节点在随机分布下实验和研...     

Existence of dumb nodes in stationary wireless sensor networks

Wireless sensor networks (WSNs), which are typically autonomous and unattended, require energy-efficient and fault-tolerant protocols to maximize the network lifetime and operations. In this work, we consider a previously unexplored aspect of the sensing nodes – dumb behavior. A sensor node is termed as “dumb”, when it can sense its surroundings, but cannot communicate with its neighbors due to shrinkage in communication range attributed to adverse environmental effects and can behave normally in the presence of favorable environment. As a result of this temporary behavior, a node may get isolated from the network when adverse environmental effects are present, but re-connects with the network with the resumption of favorable environmental conditions. We consider the effects of dumb nodes on the, otherwise, energy-efficient stationary WSNs having complete network coverage achieved using sufficient number of activated sensor nodes. While the presence of redundancy in the deployment of nodes, or the number of active nodes can guarantee communication opportunities, such deployment is not necessarily energy-efficient and cost-effective. The dumb behavior of nodes results in wastage of power, thereby reducing the lifetime of a network. Such effects can be detrimental to the performance of WSN applications. The simulation results exhibit that the network performance degrades in the presence of dumb nodes in stationary WSNs.     

Coverage and connectivity issues in wireless sensor networks: A survey

Sensing coverage and network connectivity are two of the most fundamental problems in wireless sensor networks. Finding an optimal node deployment strategy that would minimize cost, reduce computation and communication overhead, be resilient to node failures, and provide a high degree of coverage with network connectivity is extremely challenging. Coverage and connectivity together can be treated as a measure of quality of service in a sensor network; it tells us how well each point in the region is covered and how accurate is the information gathered by the nodes. Therefore, maximizing coverage as well as maintaining network connectivity using the resource constrained nodes is a non-trivial problem. In this survey article, we present and compare several state-of-the-art algorithms and techniques that aim to address this coverage–connectivity issue.     

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.