无线传感网离群点检测技术研究综述

无线传感器网络(wireless sensor network,WSN)受电池能量、计算能力、通信能力和内存空间及传感数据多维特征的限制,传统的离群点检测技术不能直接应用于WSN,因此出现了一系列针对WSN的离群点检测技术.对已有的WSN离群点检测技术进行了概述,根据各离群点检测技术的特征进行了分类和分析,并结合现有技术的缺陷和需求,展望了WSN离群点检测技术的未来研究方向和目标.     

In-network outlier detection in wireless sensor networks

To address the problem of unsupervised outlier detection in wireless sensor networks, we develop an approach that (1) is flexible with respect to the outlier definition, (2) computes the result in-network to reduce both bandwidth and energy consumption, (3) uses only single-hop communication, thus permitting very simple node failure detection and message reliability assurance mechanisms (e.g., carrier-sense), and (4) seamlessly accommodates dynamic updates to data. We examine performance by simulation, using real sensor data streams. Our results demonstrate that our approach is accurate and imposes reasonable communication and power consumption demands.     

Deployment techniques in wireless sensor networks: a survey,classification, challenges,and future research issues

The Journal of Supercomputing - Wireless sensor networks (WSNs) have been considered as one of the fine research areas in recent years because of vital role in numerous applications. To process the...     

室内环境下无线传感网络路径衰减特性

在室内环境中,墙壁的阻碍和反射会严重的影响无线传感网络中的信号传输特性.针对室内环境中传感节点的部署和应用的环境的特性,研究了无线信号在遇到墙壁反射时的传播特性,推导出了其对应的路径衰减.并基于视距传输和墙壁反射,提出了一种新的室内路径衰减模型.为了验证提出的路径衰减模型,针对室内房间和走廊环境,基于2.4 GHz载波频率,对无线传感节点的路径衰减和遮蔽效应进行了大量的实测实验.实验结果表明:提出的路径衰减模型可以很好地反映无线信号在室内的衰减特性.     

A survey on routing techniques in underwater wireless sensor networks

Underwater Wireless Sensor Networks (UWSNs) are finding different applications for offshore exploration and ocean monitoring. In most of these applications, the network consists of significant number of sensor nodes deployed at different depths throughout the area of interest. The sensor nodes located at the sea bed cannot communicate directly with the nodes near the surface level; they require multi-hop communication assisted by appropriate routing scheme. However, this appropriateness depends not only on network resources and application requirements but also on environmental constraints. All these factors provide a platform where a resource-aware routing strategy plays a vital role to fulfill the different application requirements with dynamic environmental conditions. Realizing the fact, significant attention has been given to construct a reliable scheme, and many routing protocols have been proposed in order to provide an efficient route discovery between the sources and the sink. In this paper, we present a review and comparison of different algorithms, proposed recently in order to fulfill this requirement. The main purpose of this study is to address the issues like data forwarding, deployment and localization in UWSNs under different conditions. Later on, all of these are classified into different groups according to their characteristics and functionalities.     

传感网中链路干扰优化的拓扑控制综述

拓扑控制是降低传感器网络能耗、为MAC及路由等上层协议提供支持的关键手段。对于广泛采用共享信道的传感器网络来说,并发链路的干扰严重降低了网络的传输效率、浪费了有限的网络资源。因此,降低干扰被认为是拓扑控制的最重要的目标之一。全面分析了面向链路干扰优化的传感器网络拓扑控制技术的研究进展,首先对不同的链路干扰模型进行了分析和比较,然后描述了基于不同模型的拓扑控制算法的执行流程和复杂度,分析了现有工作的特点和不足之处,同时指出了需要进一步研究的问题。     

Perimeter detection in wireless sensor networks

For a mobile robotic agent to bridge the gaps between disconnected networks, it is beneficial for the robot to first determine the network coverage boundary. Several techniques have been introduced to determine the boundary nodes of a network, but the correctness of these techniques is often ill-defined. We present a technique for obtaining boundary node ground truth from region adjacency analysis of a model-based image created from a network graph. The resulting ground truth baseline is then used for quantitative comparison of several boundary detection methods including a local application of the image region adjacency analysis and the computation of the local convex hull with the addition of a perturbation value to overcome small boundary concavities in the node location point set. Given our proposed metrics of the techniques evaluated, the perturbed convex hull technique demonstrates a high success rate for boundary node identification, particularly when the convex hull is formed using two-hop neighborhoods. This technique was successfully implemented on a physical 25-node network, and the performance of this network implementation is evaluated.     

基于无线传感器网络的车辆检测识别算法研究

针对无线传感器网络(WSNs)的特点,利用车辆发出的声音信号,提出并研究了一种改进的信号检测算法,能够有效地从被噪声严重污染的声音信号中提取出车辆信号。使用小波包变换提取16维信号特征,支持向量机进行目标分类,得到单节点识别结果。提出了基于能量的全局决策融合算法,对多个节点做出的决策进行融合,得到网络的最终识别结果。为了评估算法,使用了来自DARPA SensIT实验中的真实数据,其中包含了履带车和重型卡车的大量声音信号。实验结果表明:该算法用于WSNs中的车辆识别方面是有效的。     

Transmission power control techniques for wireless sensor networks

Communication is usually the most energy-consuming event in Wireless Sensor Networks (WSNs). One way to significantly reduce energy consumption is applying transmission power control (TPC) techniques to dynamically adjust the transmission power. This article presents two new TPC techniques for WSNs. The experimental evaluation compares the performance of the TCP techniques with B-MAC, the standard MAC protocol of the Mica 2 platform. These experiments take into account different distances among nodes, concurrent transmissions and node mobility. The new transmission power control techniques decrease energy consumption by up to 57% over B-MAC while maintaining the reliability of the channel. Under a low mobility scenario, the proposed protocols delivered up to 95% of the packets, showing that such methods are able to cope with node movement. We also show that the contention caused by higher transmission levels might be lower than analytical models suggest, due to the action of the capture effect.     

Secure localization and location verification in wireless sensor networks: a survey

The locations of sensor nodes are very important to many wireless sensor networks (WSNs). When WSNs are deployed in hostile environments, two issues about sensors’ locations need to be considered. First, attackers may attack the localization process to make estimated locations incorrect. Second, since sensor nodes may be compromised, the base station (BS) may not trust the locations reported by sensor nodes. Researchers have proposed two techniques, secure localization and location verification, to solve these two issues, respectively. In this paper, we present a survey of current work on both secure localization and location verification. We first describe the attacks against localization and location verification, and then we classify and describe existing solutions. We also implement typical secure localization algorithms of one popular category and study their performance by simulations.     

Time synchronization methods for wireless sensor networks: A survey

Wireless sensor networks consist of many nodes that collect real-world data, process them, and transmit the data by radio. Wireless sensor networks represent a new, rapidly developing direction in the field of organization of computer networks of free configuration. Sensor networks are used for monitoring a parameter field, where it is often required to fix time of an event with high accuracy. High accuracy of local clocks is also necessary for operation of network protocols (for energy-saving purposes, the nodes spend most of the time in the sleeping mode and communicate only occasionally). In the paper, base techniques used in the existing time synchronization schemes are analyzed; models of local clock behavior and models of interaction of the network devices are described; classification of the synchronization problems is presented; and a survey of the existing approaches to synchronization of time in sensor networks is given.     

无线传感器网络入侵检测系统模型

为了提高无线传感器网络的安全性,针对无线传感器网络的自身特性,设计了一种入侵检测系统模型.该模型按照聚类的方法,将区域划分成簇;在每个簇中选举簇头,簇头需定期轮换;采用基于相关向量机(RVM)的入侵检测方案.实验表明:所提出的模型与其它检测模型相比具有更高的平均检测率和更低的平均误检率,且具有低能耗的特点.     

Designing robust network topologies for wireless sensor networks in adversarial environments

In this paper, we address the problem of deploying sink nodes in a wireless sensor network such that the resulting network topology be robust. In order to measure network robustness, we propose a new metric, called persistence, which better captures the notion of robustness than the widely known connectivity based metrics. We study two variants of the sink deployment problem: sink selection and sink placement. We prove that both problems are NP-hard, and show how the problem of sink placement can be traced back to the problem of sink selection using an optimal search space reduction technique, which may be of independent interest. To solve the problem of sink selection, we propose efficient heuristic algorithms. Finally, we provide experimental results on the performance of our proposed algorithms.     

Obstacle detection and estimation in wireless sensor networks

In wireless sensor networks (WSNs), it is likely that a deployed area contains obstacles of some form. These obstacles may potentially degrade the functionality of the WSN. If the size and location of the obstacles can be detected, their influence can be reduced. Accordingly, this paper describes a scheme for detecting obstacles in WSNs. The scheme identifies the obstacles by marking the sensor nodes around the obstacle boundaries. The scheme does not require the absolute position of individual nodes in the sensing field nor any additional hardware, and thus can significantly reduce the deployment costs. The efficiency of the scheme is demonstrated via simulations performed using the network simulator ns-2. The results show that the detection scheme needs much less overhead compared to previous research while still marking the nodes close to the obstacles precisely.     

Distributed routing for signal detection in wireless sensor networks

We study the problem of energy-efficient routing for signal detection in wireless sensor networks. Generic routing protocols use networking-centric measures such as minimum hop or minimum energy to establish routes. These schemes do not take into account the performance of application-specific algorithms that is achievable from the data collected by the nodes along the routes. Routing protocols for signal detection have recently been proposed to facilitate joint optimization of detection performance and energy efficiency by developing metrics that connect detection performance with energy consumption of each link along the routes. In existing routing for signal detection (RSD) schemes, however, the routes are computed centrally requiring complex optimization algorithms and global information such as locations and observation coefficients of all nodes in the network. Clearly, for large-scale networks, or networks with dynamically changing topologies, distributed routing schemes are more practical due to their better flexibility and scalability. We present a distributed RSD protocol where each node, based on locally available information, selects its next-hop with the goal of maximizing the detection performance associated with unit energy expenditure. We show that the proposed protocol is readily implementable in ZigBee networks, and present simulation results that reveal its significant improvements in detection performance and energy efficiency over generic routing protocols.     

A survey on clustering algorithms for wireless sensor networks

The past few years have witnessed increased interest in the potential use of wireless sensor networks (WSNs) in applications such as disaster management, combat field reconnaissance, border protection and security surveillance. Sensors in these applications are expected to be remotely deployed in large numbers and to operate autonomously in unattended environments. To support scalability, nodes are often grouped into disjoint and mostly non-overlapping clusters. In this paper, we present a taxonomy and general classification of published clustering schemes. We survey different clustering algorithms for WSNs; highlighting their objectives, features, complexity, etc. We also compare of these clustering algorithms based on metrics such as convergence rate, cluster stability, cluster overlapping, location-awareness and support for node mobility.     

A survey on service-oriented middleware for wireless sensor networks

Wireless sensor networks (WSN) are used for many applications such as environmental monitoring, infrastructure security, healthcare applications, and traffic control. The design and development of such applications must address many challenges dictated by WSN characteristics on one hand and the targeted applications on the other. One of the emerging approaches used for relaxing these challenges is using service-oriented middleware (SOM). Service-oriented computing, in general, aims to make services available and easily accessible through standardized models and protocols without having to worry about the underlying infrastructures, development models, or implementation details. SOM could play an important role in facilitating the design, development, and implementation of service-oriented systems. This will help achieve interoperability, loose coupling, and heterogeneity support. Furthermore, SOM approaches will provision non-functional requirements like scalability, reliability, flexibility, and Quality of Service (QoS) assurance. This paper surveys the current work in SOM and the trends and challenges to be addressed when designing and developing these solutions for WSN.     

Practical data compression in wireless sensor networks: A survey

Power consumption is a critical problem affecting the lifetime of wireless sensor networks. A number of techniques have been proposed to solve this issue, such as energy-efficient medium access control or routing protocols. Among those proposed techniques, the data compression scheme is one that can be used to reduce transmitted data over wireless channels. This technique leads to a reduction in the required inter-node communication, which is the main power consumer in wireless sensor networks. In this article, a comprehensive review of existing data compression approaches in wireless sensor networks is provided. First, suitable sets of criteria are defined to classify existing techniques as well as to determine what practical data compression in wireless sensor networks should be. Next, the details of each classified compression category are described. Finally, their performance, open issues, limitations and suitable applications are analyzed and compared based on the criteria of practical data compression in wireless sensor networks.