无线传感器网络分簇方法的优化

现有的分布式分簇算法都是针对节点分布均匀的传感器网络设计的,不适用于节点分布不均匀的传感器网络,簇负载均衡和降低能耗成了节点不均匀部署的传感器网络的一个重要挑战。针对节点分布不均匀网络提出了一种基于区域密度的分布式分簇算法（RDCA）,算法中节点测试其所在区域的节点密度,根据区域节点密度,调节其通信的覆盖范围,从而使成簇后簇负载达到平衡。仿真实验结果显示,在节点部署不均匀的传感器网络中,本算法与LEACH、HEED相比较,可以更好地实现簇的负载平衡,有效地提高成簇后网络的稳定周期。     

能量和移动距离有效传感器网络部署

作为新兴的无线传感器网络具有十分广阔的应用场景,包括军事、环境监测、目标追踪、科学观察和预报等领域.然丽在实现各种网络协议和应用系统时,存在着一些现实约束.比如传感器节点体积微小,通常有能量十分有限的电池;但同时传感器节点个数多、分布区域广、部署区域环境复杂,通过充电或更换电池的方式来补充能源是不现实的,因此节能是无线传感器网络研究的重要目标.无线传感器网络的能量消耗直接决定了网络的使用寿命,通过有效配置传感器网络节点可以合理覆盖感知数据区域,延长网络的生命周期.采用已有传感器感知模型和虚拟力法(Virtual Force Algorithm),假设节点为势力场中的粒子,根据节点间力的作用部署节点,通过改进的虚拟力算法获得均匀的网络部署效果,达到能量有效的目的,使得网络均匀覆盖、延长网络的使用寿命.     

一种无线传感器网络节点随机部署策略

针对无线传感器网络节点随机部署的盲目性,提出一种按随机均匀分布规律部署无线传感器网络节点的策略。证明在感知区域内,随机均匀部署的大量相互独立的传感器节点数目服从泊松分布,通过建立无线传感器网络节点分布模型,得到面积覆盖率与目标区域节点分布密度之间的关系,设计在目标区域内传感器节点数量的估计方法。实验结果表明,该策略能保证无线传感器网络的覆盖性和连通性,更有效地控制网络成本。     

使用部署知识的异构传感器网络有效成簇算法

成簇算法是传感器网络中减少能量消耗的一种关键技术,它能够增强网络的扩展性和延长网络的生存时间。异构传感网络在能量节约方面的性能更好。提出一种适应异构无线传感器网络的分布式能量有效的成簇方案DEECUDK。该方案首先利用部署知识部署节点,使能量在整个监测区域分布比较均匀,然后以节点的剩余能量与传感半径之内的节点的剩余覆盖能量为主参数,其相邻节点个数为辅参数来选举簇头节点。较高初始能量、剩余能量和相邻节点数多的节点比其他节点拥有更多的机会成为簇头节点,并引入活动节点判别式,不需要增加任何开销来减少簇内冗余数据量,从而使网络能量均匀消耗,延长网络的生存时间。通过模拟实验结果,与现有的异构传感网络成簇算法相比,新的算法在网络生存时间与网络吞吐量方面有着更好的性能。     

一种改进的无线传感器网络节点部署方案

现有的无线传感器网络节点部署方案需要额外探测和修复边界上的覆盖空洞,增加了网络部署的成本,且节点分布不均匀.为此,提出一种改进的节点部署方案.通过边界部署保证边界上的完全覆盖和连通,在感应区域内生成一个新的凸多边形区域,在新区域上递归调用边界部署算法,直到整个感应区域被完全覆盖.理论分析和仿真实验结果表明,该方案能够保证网络的1-连通性和完全覆盖,消除任务区域存在的边界效应,在部署节点个数和可扩展性方面均优于已有的部署方案.     

改进的非均匀有向传感器网络节点部署方法

在无线传感器网络的相关研究中,有向传感器网络DSNs（Directional Sensor Networks）由于在节点属性上增设了有向属性而使其拥有更为广阔的实用意义。针对重点区域覆盖不足的问题,提出了一种改进的非均匀有向传感器网络节点部署方法,引入部署中心和矢量引力的概念,增加斥力的非均匀部署属性,从而加强区域内的覆盖质量。通过实验对比表明,改进后的部署方法在有效节点数量及覆盖率方面均优于一般的有向传感器网络节点部署方法。     

基于虚拟方格的区域密度覆盖算法

当随机部署的信标节点集中在监视区域边界处时,仅依靠虚拟力无法均匀部署。针对该问题,提出基于虚拟方格的区域密度覆盖算法,根据节点密度将整个区域划分为虚拟方格,每次迭代根据区域密度更新虚拟力系数。利用边界力避免信标节点处于区域边界或死角,使信标节点合理分布在监视区域中。仿真结果证明,该算法可有效提高信标节点网络覆盖率。     

基于改进蝙蝠算法的无线传感器网络的移动节点部署

针对传统的无线传感器网络(WSNs)中存在的移动节点部署的分布不均匀、网络覆盖度太低等各种问题,提出了一种基于改进蝙蝠算法(BA)的移动节点部署策略,通过蝙蝠算法的收敛特性,不断迭代寻求问题的最优解,从而不断优化传感器节点的部署.Matlab仿真表明:提出的算法可以显著改善传感器节点的覆盖密度,并且节点分布也相对比较均匀.     

无线传感器网络中传感器节点的布置

在无线传感器网络中，传感器节点收集本地数据，通常通过其它节点将数据转发给基站，因而离基站越近的节点，消耗的能量越多．如果采用通常的方法，即均匀布置传感器节点，则基站附近的节点将很快消耗完能量，基站也就无法收集数据．本文通过研究无线传感器网络中的能量消耗，得到了一个布置传感器节点的密度函数，按此函数布置传感器节点可以有效地延长系统的生命期．理论分析和模拟结果表明，本文的布置方案将系统生命期提高到均匀布置方案的3R/2t倍，这里t为传感器节点的通信距离，R为传感器节点的分布区域半径．     

线型无线传感器网络的节点部署策略

尽可能延长无线传感器网络的生命周期是设计和部署网络所面临的最大挑战之一。由于节点配备的能量有限,节点通常采用多跳方式向基站传输数据。分析了节点在多跳通信时的能耗,提出一种非均匀的节点部署策略,得出一个部署传感器节点的密度函数,在靠近基站的区域部署较多的节点。仿真实验表明,非均匀的节点部署策略能有效延长网络的生命周期。     

输电线路在线监测WSNs优化部署研究

应用于输电线路在线监测的无线传感器网络(WSNs)通常呈长链型,存在跳数多、时延大的问题。引入具备无线公网通信模块的异构节点能够优化WSNs时延性能。考虑网络中传感器节点分布不均匀引起的数据分布不均匀这一普遍现象及其对时延的影响,建立了异构WSNs的最大时延模型;同时考虑网段划分和异构节点部署对时延的影响,提出了一种基于局部搜索思想的网络优化部署方法来优化网络时延。仿真结果表明:上述方法能有效降低网络最大时延,提高网络实时性。     

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.     

一种基于网格地理哈希表的无线传感器网络数据分发算法

无线传感器网络是一种新型数据监测网络，其重要特性是传感器节点的能量有限，一般依靠电池驱动，能量效率是传感器网络设计最重要的考虑因素。GHT-DCS是一种新型能量高效的数据分发方式，能在数据的查询和存储之间取得一种平衡。但是，采用GHT-DCS机制的能量效率仍然有改进的空间。本文提出了一种基于网格GHT的数据分发算法，也是一种以数据为中心的存储，并在此算法的基础上提出了一种基于索引存储的网格GHT数据分发算法，能更进一步提高能量效率。本文对这两种算法进行了性能分析，与原有的GHT算法进行了性能对比。分析表明，这两种算法在性能上都比原GHT算法有很大改进，而复杂度增加较少，是能量更加高效的数据分发算法。     

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.     

Optimal movement-assisted sensor deployment and its extensions in wireless sensor networks

In wireless sensor networks (WSNs), a good sensor deployment method is vital to the quality of service (QoS) provided by WSNs. This QoS depends on the coverage of the monitoring area. In WSNs with locomotion facilities, sensors can move around and self-deploy to ensure coverage and load balancing, where each unit of monitoring area is covered by the same number of sensors. The movement-assisted sensor deployment deals with moving sensors to meet coverage and load balancing requirements. In SMART [J. Wu, S. Yang, SMART: a scan-based movement-assisted sensor deployment method in wireless sensor networks, in: Proceedings of INFOCOM, 2005], various optimization problems are defined to minimize different parameters, including total moving distance, total number of moves, communication/computation cost, and convergence rate. In this paper, we focus on minimizing the total moving distance and propose an optimal, but centralized solution, based on the Hungarian method. This solution is illustrated in an application where the monitoring area is a 2-D grid-based mesh. We then propose several efficient, albeit non-optimal, distributed solutions based on the scan-based solution in Wu and Yang (2005). Extensive simulations have been done to verify the effectiveness of the proposed distributed solutions.     

基于Grid-VFACO的数字化车间WSNs路由算法

针对数字化车间中无线传感器网络(WSNs)对数据采集频率高,能量消耗快,提出了基于网格和虚拟力导向的蚁群优化(Grid-VFACO)高能效WSNs路由算法。该算法根据最优簇首数将数据采集区划分成网格,在网格中采用基于候选者的机制选择簇首,实现簇首均匀分布。在簇首形成的上层网络中,利用节点间的虚拟吸引力作为蚁群算法中转移概率规则启发因子,寻找最优数据转发路径。仿真实验结果表明:该算法能够有效减少网络能耗,保证数字化车间WSNs长时间稳定地工作。     

一种应用无线传感器网络观测泥石流的方法

介绍了泥石流的形成机理,对现阶段的泥石流监测方法进行了分析和比较,给出了基于无线传感器网络的泥石流关键因子的小尺度观测方法,阐述了传感器节点的硬件构造方法、节点部署方法和节能通信协议。传感器网络不仅为泥石流机理的深入研究提供了数据源,也为泥石流灾害预报和预警机制的建立奠定了基础,有助于降低泥石流地质灾害的损失。     

Quality-driven secure audio transmissions in wireless multimedia sensor networks

Many audio applications such as audio surveillance and human acoustic health monitoring require security protections for audio streaming over WSNs. The process of watermarking which embeds small amounts of data (i.e., the watermark) into the original audio is an effective technique to ensure the integrity of received audio data at the receiver in energy-constrained WSNs. However, the selection of positions to embed watermark into audio streams is critical to both received audio quality and watermarking authentication performance in error-prone wireless transmission environments. In this paper we propose an approach that dynamically determines the range of middle sub-band components for embedding the watermark with minimum quality distortions, based on psycho-acoustic models and adaptive sub-band thresholds. In addition, through unequal network resource allocation schemes the proposed approach protects both middle sub-bands and high sub-bands, which include the important audio components. Our theoretical analysis and simulation results demonstrate that the proposed quality-driven energy-efficient watermarking approach for audio transmissions can achieve considerable performance gains in WSNs.     

一种简易的井下巷道冗余节点部署策略

针对井下巷道狭长、通信环境复杂的情况,提出一种非常简单且易于执行的无线传感器网络节点部署策略—基于等腰三角形的冗余节点部署策略。它能够保证巷道至少被三重覆盖,满足了移动节点的定位要求,同时,节点的冗余部署能够在个别节点失效时仍维持数据的稳定传输。实验环境下测试结果表明：此种部署策略能够在不增加过多监测节点的同时,保证网络的低丢包率,并实现对移动节点的定位。     

无线传感器网络监测区内节点能耗估计

该文通过对传感器网络监测域内节点能耗建模与节点在区域中的理想网络部署建模，从理论上分析了传感器网络最优部署时各处位置的节点能耗变化趋势，并总结出了EC能耗曲线。以J—Sim为仿真平台．仿真试验提取了特定条件下测试区内不同位置的节点能耗并依此绘制成曲线与EC曲线拟合，验证了EC曲线的有效性。将依据EC曲线计算出的网络寿命上限与文献[9]提出的网络寿命上限结果比较可知，由该模型得到的网络寿命上限以及节点能耗曲线更加逼近真实网络。