Robust distributed video coding for wireless multimedia sensor networks

Multimedia Tools and Applications - Coding complexity and error-resilience are the two key factors for video streaming in Wireless Multimedia Sensor Networks (WMSNs). Towards this objective, this...     

Connectivity monitoring in wireless sensor networks

Connectivity monitoring is useful in practical deployment of wireless sensor network. In order to understand the behavior and performance bottleneck, knowledge of the network connectivity is crucial. In this paper, we propose a flexible and efficient connectivity monitoring algorithm (H²CM) that has three components and operates in a divide-and-conquer manner. The components include hop vector distance based filtering, Bloom filters and signature hashing and are designed to work with different combinations of network and neighbor set sizes. In simulation, communication cost reduction of H²CM compare to maximal compression of neighborhood information varies from 65% to 85% for large networks (>1000 nodes) and from 40% to 70% for a medium size network (a few hundred nodes). We have also implemented the algorithm in TinyOS and evaluated its performance on a testbed with 34 motes. Lastly, we study the problem of node failure detection — a simple application of connectivity monitoring. We show that by combining H²CM with the concept of dominating set, the communication cost can be drastically reduced compare to traditional data collection method.     

Routing in wireless sensor networks for wind turbine monitoring

Smart wireless sensor devices are rapidly emerging as key enablers of the next evolution in wind turbine monitoring. The potential for in-situ monitoring of turbine elements, employing methodologies that are not possible with existing wired technology, make it possible to attain new levels of granularity and autonomy in the monitoring of these structures. Wireless sensor devices are limited in terms of communication by the range of their radio modules and, thus, need to form networks in order to transfer data from distant points. Routing protocols are primary enablers of such ad hoc wireless sensor networks and these require the implementation of reliable and energy-efficient mechanisms to maximize network reliability and availability. Existing routing protocols cannot be directly applied to the monitoring of wind turbines without addressing the unique context and operational characteristics of these structures in multi-hop wireless communication. This work identifies the potential effects associated with the operation, environment and structure of wind turbines in wireless sensor network multi-hop communication, and proposes and evaluates a reliable routing protocol for wireless sensor networks employed in these domains.     

无线传感器网络节点的电压监测

电池供电的无线传感器网络节点在电量不足时,节点上的有源器件不能稳定工作。基于网络节点中的CC2430/31芯片,在Zig Bee协议栈中添加定时功能,使以电池供电的节点能够周期性地采样电池电压并进行判断,当电压低于预先设定的报警低限时,利用LED灯的闪烁进行报警。同时该节点进入非正常工作状态,断开与网络的联系,以保证其他节点交互信息的可靠性。     

Self-organization of unattended wireless acoustic sensor networks for ground target tracking

A distributed, self-organization algorithm for ground target tracking using unattended acoustic sensor network is developed. Instead of using microphone arrays, each sensor node in the sensor network uses only a single microphone as its sensing device. This design can greatly reduce the size and cost of each sensor node and allow more flexible deployment of the sensor network. The self-organization algorithm presented in this paper can dynamically select proper sensor nodes to form the localization sensor groups that can work as a virtual microphone array to perform energy efficient target localization and tracking. To achieve this, we use a time-delay based bearing estimation plus triangulation for source localization in the sensor network. Major error sources of the localization method like time delay estimation, bearing calculation and triangulation are analyzed and sensor selection criteria are developed. Based on these criteria and neighborhood information of each sensor node, a distributed self-organization algorithm is developed. Simulation results show the effectiveness of the proposed algorithm.     

事件驱动型无线传感器网络能量监测机制研究

在分析现有无线传感器网络能量监测机制的基础上,针对事件驱动型无线传感器网络,提出EDEMM机制.该机制采用成簇结构,簇成员周期性地监测自身剩余能量,当且仅当能量消耗的幅度较大时才向簇头节点汇报,簇头对簇成员发来的消息进行处理,当簇头融合后的能量超过一定幅度时向汇聚节点汇报.仿真结果表明:EDEMM机制降低了能量消息包的数量,有效地降低了能耗,可以延长网络的使用寿命.     

农田环境信息监测的无线传感器网络节点设计

针对电子信号干扰、能耗大等因素对通信能力造成的影响,设计了基于低功耗微处理器MSP430的无线传感器网络节点.通过使用MCU的不同工作模式和对无线射频模块的不同状态等节能措施,增强了节点通信能力,大幅度降低了节点的能耗.经过背景项目实际农田环境的测试证明:节点不仅能够完成对农田环境要求信息进行准备采集,网络通信效率也得...     

基于大坝监测的无线传感器网络结构的设计

针对大坝安全监测的特点,充分利用多跳和分簇的优势,在对几种典型无线传感器网络进行比较的基础上,提出了一种应用于大坝监测的无线传感器网络结构。功耗、可靠性等性能分析论证了其可行性。     

Congestion control in wireless sensor networks based on bird flocking behavior

This paper proposes that the flocking behavior of birds can guide the design of a robust, scalable and self-adaptive congestion control protocol in the context of wireless sensor networks (WSNs). The proposed approach adopts a swarm intelligence paradigm inspired by the collective behavior of bird flocks. The main idea is to ‘guide’ packets (birds) to form flocks and flow towards the sink (global attractor), whilst trying to avoid congestion regions (obstacles). The direction of motion of a packet flock is influenced by repulsion and attraction forces between packets, as well as the field of view and the artificial magnetic field in the direction of the artificial magnetic pole (sink). The proposed approach is simple to implement at the individual node, involving minimal information exchange. In addition, it displays global self-1 properties and emergent behavior, achieved collectively without explicitly programming these properties into individual packets. Performance evaluations show the effectiveness of the proposed Flock-based Congestion Control (Flock-CC) mechanism in dynamically balancing the offered load by effectively exploiting available network resources and moving packets to the sink. Furthermore, Flock-CC provides graceful performance degradation in terms of packet delivery ratio, packet loss, delay and energy tax under low, high and extreme traffic loads. In addition, the proposed approach achieves robustness against failing nodes, scalability in different network sizes and outperforms typical conventional approaches.     

基于无线传感器网络的自适应声源定位算法

基于声源能量的无线传感器网络（ WSNs）最大似然定位算法抗噪声干扰能力强,定位精度高,同时适用于多个目标定位,但是计算量大,不适用于实时定位。针对现有算法的缺点,提出了一种基于自适应迭代的最大似然定位算法。该算法将代价函数作为目标函数,在给定的梯度误差范围内自适应地搜索目标位置。为了提高算法的收敛速度和定位精度,提出了基于Sigmoid函数的变步长的搜索算法。仿真实验结果表明：与最大似然定位算法相比,自适应迭代算法运算量小,定位精度高,能满足对目标定位精度和速度要求较高的场合,具有一定的实际应用意义。     

基于无线传感器网络的危险物在途监控系统

提出了一种基于无线传感器网络的在途危险物实时动态监控系统.该系统可根据不同运输工具及危险物种类选择安装相应传感器节点并无线自主组网,通过通用分组无线业务(GPRS)实现远程无线数据访问与传输,使得控制中心能够对运输过程中危险物的状态进行全程跟踪、实时动态监控.给出了系统结构和软硬件的设计方案.实验结果表明:设计的系统测量误差较小,能够满足实际使用要求.     

基于无线传感器网络的水环境监测系统

基于传感器网络特性,采用嵌入式、无线传感器网络的搭建、面向对象的软件开发等技术,开发了面向水环境的传感器自动监测、预警、分析系统,该系统实现了对水质进行监测、对异常数据自动预警、对各年度数据进行对比,从而对未来做出预测的功能.实验表明:该系统有一定的推广价值.     

Localized monitoring of kNN queries in wireless sensor networks

Wireless sensor networks have been widely used in civilian and military applications. Primarily designed for monitoring purposes, many sensor applications require continuous collection and processing of sensed data. Due to the limited power supply for sensor nodes, energy efficiency is a major performance concern in query processing. In this paper, we focus on continuous kNN query processing in object tracking sensor networks. We propose a localized scheme to monitor nearest neighbors to a query point. The key idea is to establish a monitoring area for each query so that only the updates relevant to the query are collected. The monitoring area is set up when the kNN query is initially evaluated and is expanded and shrunk on the fly upon object movement. We analyze the optimal maintenance of the monitoring area and develop an adaptive algorithm to dynamically decide when to shrink the monitoring area. Experimental results show that establishing a monitoring area for continuous kNN query processing greatly reduces energy consumption and prolongs network lifetime.     

基于无线传感器网络的多参数家庭监护系统

多参数无线家庭监护系统设计目的是为老人和残障人士提供心电、血氧、血压、呼吸和体温等各种生理参数的检测。系统采用了基于芯片nRF24L01的无线通信模式,并利用非标准通信协议进行管理。实验结果表明：该系统可以实现对病人的远程监护,让医生能随时掌握病人的情况,确保病人的及时医治。     

基于WSN的农业生态环境监控

针对农业生态环境实时监控的需要,以无线射频芯片CC2430为核心设计了基于无线传感器网络(WSN)的农业生态环境监控系统。详细介绍了该监控系统的拓扑结构及软硬件设计思路,采用ML-MAC数据链路层协议并提出基于簇头负载均衡的WSN分簇节能路由算法(CLBCES),进一步降低了功耗和成本,非常适合在规模化农业生产中广泛使用。     

无线传感器网络在机械振动监测中的应用

为了弥补目前基于有线连接机械振动监测系统中的线缆布设复杂、成本高、可维护性差、系统灵活性差等一些不足,把无线传感器网络引入机械振动监测中,并采用基于关系矩阵的数据融合算法解决机械振动监测中数据量大的问题。实验表明:关系矩阵数据融合算法可以在有效提高监测精度的同时减少传输的数据量。无线传感器网络可以实现对被监测设备的实时监测,使工作人员及早发现被监测设备的故障。     

基于ZigBee无线传感器网络的起重机监控系统

结合ZigBee无线通信技术,提出一种应用于起重机监控的无线传感网络系统架构。该方案网络节点硬件电路以MC9SDG128为控制器、CC2530为射频收发器,详细规划了网络中节点硬件和软件设计,并介绍上位监控系统。该系统具有低成本、低功耗、易扩展、安全性高等特点,能实时监控起重机的运行状况,可广泛应用于起重机监控系统。     

基于无线传感器网络的地震监测系统设计

针对传统有线网络难以有效进行地震监测的问题,设计了基于无线传感器网络的地震监测系统。分析了该监测系统的结构,介绍了所设计的地震监测系统节点硬件组成和完成相关功能的软件系统。应用新一代AVR芯片灵活控制,及9X Tend OEM强大的数据传输功能,简化了网络拓扑,能够适应复杂多变的环境,监测各种有线网络无法有效监测的地区,实现灾难预警与救助。     

基于无线传感器网络的远距离结构健康监测

针对复合材料结构健康监测的特点和需求,实现了一套基于无线传感器网络(WSNs)的远距离结构健康监测系统。系统构成包括前端传感监测子系统、WSNs子系统和远终端监控子系统。为了扩大系统的监测范围,降低系统网络功耗及成本,提高系统的稳定性、智能性和抗毁性,研究了自制的无线传感节点、多跳路由技术及小型化配接电路,改进了终端程序和网络节点程序。实验证明:相对于传统有线的监测方式,基于WSNs的结构健康监测具有灵活性高、负重轻、成本低、搭建移动方便、维护容易等优点。