Wireless sensor networks for emergency navigation

In an emergency, wireless network sensors combined with a navigation algorithm could help safely guide people to a building exit while helping them avoid hazardous areas. We propose a distributed navigation algorithm for emergency situations. At normal time, sensors monitor the environment. When the sensors detect emergency events, our protocol quickly separates hazardous areas from safe areas, and the sensors establish escape paths. Simulation and implementation results show that our scheme achieves navigation safety and quick convergence of the navigation directions. We based our protocol on the temporally ordered routing algorithm for mobile ad hoc networks. TORA assigns mobile nodes temporally ordered sequence numbers to support multipath routing from a source to a specific destination node.     

无线传感器网络中基于位置信息的路由算法研究

为了保证移动无线传感器网络中数据的高效稳定传输,提出了一种基于地理位置信息支持多个移动sink的路由算法.该算法将监测区域分成一个固定不变的规则网格网络,并对网格簇头节点的选举方法进行了改进;通过数据的冗余传递和搜索框、候选转发节点集合的设置保证了数据传送的可靠性与时延性;同时容忍圆的引入保证了低功耗的要求.仿真结果表明,该算法较两层数据分发协议有更高的传输可靠性和较低的功耗.     

Energy-efficient area monitoring for sensor networks

The nodes in sensor networks must self-organize to monitor the target area as long as possible. Researchers at the Fundamental Computer Science Laboratory of Lille are developing strategies for selecting and updating an energy-efficient connected active sensor set that extends the network lifetime. We report on their work to optimize energy consumption in three separate problems: area coverage, request spreading, and data aggregation.     

Energy-saving models for wireless sensor networks

Nowadays, wireless sensor networks are being used for a fast-growing number of different application fields (e.g., habitat monitoring, highway traffic monitoring, remote surveillance). Monitoring (i.e., querying) the sensor network entails the frequent acquisition of measurements from all sensors. Since sensor data acquisition and communication are the main sources of power consumption and sensors are battery-powered, an important issue in this context is energy saving during data collection. Hence, the challenge is to extend sensor lifetime by reducing communication cost and computation energy. This paper thoroughly describes the complete design, implementation and validation of the SeReNe framework. Given historical sensor readings, SeReNe discovers energy-saving models to efficiently acquire sensor network data. SeReNe exploits different clustering algorithms to discover spatial and temporal correlations which allow the identification of sets of correlated sensors and sensor data streams. Given clusters of correlated sensors, a subset of representative sensors is selected. Rather than directly querying all network nodes, only the representative sensors are queried by reducing the communication, computation and power costs. Experiments performed on both a real sensor network deployed at the Politecnico di Torino labs and a publicly available dataset from Intel Berkeley Research lab demonstrate the adaptability and the effectiveness of the SeReNe framework in providing energy-saving sensor network models.     

无线传感器网络的RSSI定位技术研究

在许多无线传感器网络应用中,定位已经成为一个基本的服务需求.分析了基于接收信号强度(RSS)测量模型的位置估计,详细地推导了单个盲节点位置的概率密度函数并分析两个盲节点位置的概率分布的关系,通过该模型的极大似然估计可以得出盲节点位置,而且在此基础上修正了该定位估计算法,使得系统中盲节点越多其估计位置的精度越高,最后通过有效的仿真验证了算法.     

传感器网络中基于连通支配集的路由算法

针对传感器网络节点资源有限的特点,结合连通支配集的概念,提出了基于小连通支配集的路由算法,算法通过高效地构造最小连通支配集形成一个虚拟骨干网,使得数据转发可以高效地进行,而且算法是层次式的,具有良好的可扩展性,模拟实验和理论分析也表明算法具有良好的性能。     

Energy-efficient bootstrapping for wireless sensor networks

Wireless sensor networks are poised for increasingly wider uses in many military and civil applications. Such applications has stimulated research in a number of research areas related to energy conservation in such networks. Most such research focuses on energy saving in tasks after the network has been organized. Very little attention has been paid to network bootstrapping as a possible phase where energy can be saved. Bootstrapping is the phase in which the entities in a network are made aware of the presence of all or some of the other entities in the network. This paper describes a bootstrapping protocol for a class of sensor networks consisting of a mix of low-energy sensor nodes and a small number of high-energy entities called gateways. We propose a new approach, namely the slotted sensor bootstrapping (SSB) protocol, which focuses on avoiding collisions in the bootstrapping phase and emphasizes turning off node radio circuits whenever possible to save energy. Our mechanism synchronizes the sensor nodes to the gateway’s clock so that time-based communication can be used. The proposed SSB protocol tackles the issue of node coverage in scenarios, when physical device limitations and security precautions prevent some sensor nodes from communicating with the gateways. Additionally, we present an extension of the bootstrapping protocol, which leverages possible gateway mobility.     

无线传感器网络的覆盖控制

覆盖控制作为无线传感器网络中的一个基本问题,在国内外已经取得了一些研究成果。根据不同的性质,覆盖控制问题可以划分为不同的类型(如,静态覆盖和动态覆盖、确定性覆盖和随机性覆盖)。主要针对静态覆盖(区域覆盖、点覆盖、栅栏覆盖)问题中一些典型算法,分类进行了描述,并比较了它们之间的优缺点,最后,指出了需要进一步的研究工作。     

一种无线传感器网络链式传输分簇路由协议

由于周围环境对无线传感器网络(WSNs)的影响,在布设到特殊环境下时会产生信号的衰减与损耗,导致通信不畅。针对此问题,提出一种以LEACH路由协议为基础适应特殊环境(长直空间)的新型路由算法。本算法采用链式传输,即从内部逐一将信号传输给距空间最外端且距基站位置较近的簇头,克服了内部节点死亡过快的问题。同时簇内采用链式传输并且改进簇头阈值与成簇半径,减小了能量消耗,提高了稳定性,克服了LEACH算法的不足。     

Environmental sensor networks

The developments in wireless network technology and miniaturization makes it possible to realistically monitor the natural environment. Within the field of environmental sensor networks, domain knowledge is an essential fourth component. Before designing and installing any system, it is necessary to understand its physical environment and deployment in detail. Sensor networks are designed to transmit data from an array of sensors to a server data repository. They do not necessarily use a simple one way data stream over a communication network rather elements of the system decide what data to pass on, using local area summaries and filtering to minimize power use while maximizing the information content. The Envisense Glacs Web project is developing a monitoring system for a glacial environment. Monitoring the ice caps and glaciers provides valuable information about the global warming and climate change.     

The best keying protocol for sensor networks

Many sensor networks (especially networks of mobile sensors or networks that are deployed to monitor crisis situations) are deployed in an arbitrary and unplanned fashion. Thus, any sensor in such a network can end up being adjacent to any other sensor in the network. To secure the communications between every pair of adjacent sensors in such a network, each sensor $x$ in the network needs to store $n?1$ symmetric keys that sensor $x$ shares with all the other sensors, where $n$ is an upper bound on the number of sensors in the network. This storage requirement of the keying protocol is rather severe, especially when $n$ is large and the available storage in each sensor is modest. Earlier efforts to redesign this keying protocol and reduce the number of keys to be stored in each sensor have produced protocols that are vulnerable to impersonation, eavesdropping, and collusion attacks. In this paper, we present a fully secure keying protocol where each sensor needs to store $(n+1)/2$ keys, which is much less than the $n?1$ keys that need to be stored in each sensor in the original keying protocol. We also show that in any fully secure keying protocol, each sensor needs to store at least $(n?1)/2$ keys.     

Robot and sensor networks for first responders

The need to collect, integrate, and communicate information effectively in emergency response scenarios exceeds the state of the art in information technology. This emergency response problem provides an interesting and important test bed for studying networks of distributed mobile robots and sensors. Here, we describe the component technologies required to deploy a networked-robot system that can augment human firefighters and first responders, significantly enhancing their firefighting capabilities. In a burning building at a firefighting training facility, we deployed a network of stationary Mote sensors, mobile robots with cameras, and stationary radio tags to test their ability to guide firefighters to targets and warn them of potential dangers. Our long-term vision is a physical network that can sense, move, compute, and reason, letting network users (firefighters and first responders) Google for physical information - that is, information about the location and properties of physical objects in the real world.     

Voronoi-based localisation algorithm for mobile sensor networks

Localisation is an essential and important part in wireless sensor networks (WSNs). Many applications require location information. So far, there are less researchers studying on mobile sensor networks (MSNs) than static sensor networks (SSNs). However, MSNs are required in more and more areas such that the number of anchor nodes can be reduced and the location accuracy can be improved. In this paper, we firstly propose a range-free Voronoi-based Monte Carlo localisation algorithm (VMCL) for MSNs. We improve the localisation accuracy by making better use of the information that a sensor node gathers. Then, we propose an optimal region selection strategy of Voronoi diagram based on VMCL, called ORSS-VMCL, to increase the efficiency and accuracy for VMCL by adapting the size of Voronoi area during the filtering process. Simulation results show that the accuracy of these two algorithms, especially ORSS-VMCL, outperforms traditional MCL.     

Revisiting public-key cryptography for wireless sensor networks

The lack of a fixed infrastructure and the ad hoc nature of wireless sensor networks deployments suggest that the ability to encrypt and decrypt confidential data among arbitrary sensor nodes while enabling undisputed authentication of all parties will be a fundamental prerequisite for achieving security. To do this, nodes must be able to establish a secret key and know who their counterparts are. Thus, it becomes highly desirable to have a secure and efficient distribution mechanism that allows simple key generation for large-scale sensor networks while facilitating all the necessary authentications.     

传感器网络中一种负载平衡的选播路由算法

针对传感器网络的特点,提出了一种基于权重负载平衡的选播路由算法.该算法的基本思想是根据路径上传输数据的能量消耗、邻居节点的剩余能量和跳数信息计算权重,并选择最小权重路径.新算法通过利用权重让更多节点分担数据传输以保持网络负载平衡,延长网络生存期和改善选播路由的性能.仿真实验表明,新算法的网络生存期是SARP的2到4倍,具有良好的路由性能.     

一种无线传感器网络的密钥管理机制

介绍了一种用于无线传感器网络(WSNs)的密钥预分配机制:多密钥空间哈希随机密钥预分配(HARPMS)机制。该机制针对group-based节点投放模型,将密钥空间划分成多个子空间,在密钥分配和建立时使用Hash链技术,以提高网络的抗节点俘获能力。分析表明:相比传统的用于group-based投放模型的随机密钥预分配机制,HARPMS获得了同等的连通性,但却有更好的抗节点俘获能力。     

Quality-of-service trade-off analysis for wireless sensor networks

Quality of Service (QoS) support for wireless sensor networks (WSN) is a fairly new topic that is gaining more and more interest. This paper introduces a method for determining the node configurations of a WSN such that application-level QoS constraints are met. This is a complex task, since the search space is typically extremely large. The method is based on a recent algebraic approach to Pareto analysis, that we use to reason about QoS trade-offs. It features an algorithm that keeps the working set of possible configurations small, by analysing parts of the network in a modular fashion, and meanwhile discarding configurations that are inferior to other configurations. Furthermore, we give WSN models for two different applications, spatial mapping and target tracking, in which QoS trade-offs are made explicit. Test results for these applications and a heterogeneous WSN combining these two applications show that the models are accurate and that the method is scalable and thus practically usable for WSN, even with large numbers of nodes. Details are given on how to efficiently implement the algorithm.     

GPS-less location algorithm for wireless sensor networks

The node location problem in wireless networks has been a research interest in the last years. In environments where GPS is not an option (e.g., for consumption reasons or because there is no direct link with the satellite constellation), the estimation of a node position using only RF signals is not a trivial task. Although some other systems have been proposed (ultrasonic signals, IR, etc.), these require additional hardware that is only useful for location purposes. According to this point, some algorithms have been proposed for providing sensible position estimations in the presence of distance errors. These methods normally require heavy computational processes to overcome the presence of these errors or easily degrade when the distance measurements have a certain magnitude. This paper describes an algorithm to compute the location of a node in the presence of severe distance estimation errors and analyzes its performance and computational cost. To make the implementation of this algorithm feasible in wireless sensor networks, different optimization techniques are proposed, in order to speed-up the location estimation of a node, without losing its estimating power.