UWB wireless sensor networks: UWEN - a practical example

The research topic of sensor networks has been around for some time. With improvements in device size, power consumption, communications, and computing technology, sensor networks are becoming more popular for an ever increasing range of applications. Since 2002, there has been an increased in the popularity of commercial applications based on ultra wideband. This, in turn, has ignited interest in the use of this technology for sensor networks and fuelled research in the area. Impulse-radio-based UWB technology has a number of inherent properties that are well suited to sensor network applications. In particular, UWB systems have potentially low complexity and low cost, have noise-like signal, are resistant to severe multipath and jamming, and have very good time domain resolution allowing for location and tracking applications. This article examines one example of a UWB sensor network for outdoor sport and lifestyle applications.     

An ultrawideband system architecture for tag based wireless sensor networks

With the latest improvements in device size, power consumption, and communications, sensor networks are becoming increasingly more popular. There has also been a great increase in the popularity of commercial applications based on ultrawideband (UWB). Impulse radio (IR) based UWB technology utilizes noise-like signal, has potentially low complexity and low cost, is resistant to severe multipath, and has very good time domain resolution allowing for location and tracking applications. In this paper, the architecture and performance of a noncoherent low complexity UWB impulse radio based transceiver designed for low data rate, low cost sensor network applications is presented. The UWB-IR transmitter is based on a delay locked loop (DLL) and UWB monocycle pulse generator. The UWB-IR receiver utilises a noncoherent, energy detection based approach, which makes it largely independent of the shape of the transmit waveform and robust to multipath channels. The test circuits are designed for 0.35 /spl mu/m SiGe BiCMOS technology. This paper presents system simulations results as well as the performance of key functional blocks of the designed UWB application specific integrated circuit (ASIC) transceiver architecture. The simulated power consumption of UWB-IR transceiver circuits is 136 mW with 100% duty cycle with a 3.3 V power supply.     

提高无线传感器网络信息安全的时间反演技术

近年来无线传感器网络被广泛应用于三维立体监测、分布式监测、目标跟踪、空间探索、随机分布测量等领域.由于无线传感器网络在军事上的特殊用途,如敌情侦察、兵力监控及其它的特殊用途,使其信息传输的安全性研究得到广泛关注.通过引入一种新技术——时间反演(TR,Time Reversal)技术,来降低信号在空间与时间上被非法检测到的概率.时间反演技术使得信号只有在特定的时间和特定的空间内才可以被检测出来,而超出这个范围信号很难被检测出来,从而提高了无线传感器网络的信息安全.     

UWB radio module design for wireless sensor networks

In this paper, we describe an impulse-based ultra wideband (UWB) radio system for wireless sensor network (WSN) applications. Different architectures have been studied for base station and sensor nodes. The base station node uses coherent UWB architecture because of the high performance and good sensitivity requirements. However, to meet complexity, power and cost constraints, the sensor module uses a novel non-coherent architecture that can autonomously detect the UWB signals. The radio modules include a transceiver block, a baseband processing unit and a power management block. The transceiver block includes a Gaussian pulse generator, a multiplier, an integrator and timing circuits. For long range applications, a wideband low noise amplifier (LNA) is included in the transceiver of the sensor module, whereas in short range applications it is simply eliminated to further reduce the power consumption. In order to verify the proposed system concept, circuit level implementation is studied using 1.5 V 0.18 μm CMOS technology. Finally, the UWB radio modules have been designed for implementation in liquid-crystal-polymer (LCP) based System-on-Package (SoP) technology for low power, low cost and small size integration. A small low cost, double-slotted, Knight’s helm antenna is embedded in the LCP substrate, which shows stable characterization and a return loss better than ?10 dB over the UWB band.     

无线传感网分布式密钥分配方案综述

近年来,无线传感网以其特殊的军事、商业前景而广泛受到关注,与传统有线网络相比,无线传感网有着自己的优势和特性,而在信息社会,信息安全无疑是研究的一个重要方向。至此,国内外学者对无线传感网的安全性进行了大量研究,尤其是在密钥分配这一方面,首先对密钥分配的概念进行阐述,针对无线传感网自身特点,选取了较为合适的分布式密钥分配方案,分析了几种方案的基本原理,并分别从安全性、通信计算开销和效率等角度分析了其优势和不足,最后,在此基础上进行总结与展望。     

对无线传感器网络寻址方式的研究

寻址方式是影响WSN(无线传感器网络)工作效率的重要因素,如何根据WSN的业务特点,设计低开销、低存储、低计算复杂度的高效寻址方式,是值得深入研究解决的问题.本文在深入分析WSN一般业务类型和寻址特点的基础上,重点对当前WSN中的一些主要寻址方式做了系统、深入的分析,并得出了几点重要结论.     

基于WSN的公路监控系统设计

WSN作为一种新兴的应用型技术,具有体积小、成本低、功耗小和组网灵活方便等优点,其广泛的应用也在改变着人们的生活。当今交通安全问题已成为政府和人们日益关注的话题,针对当今公路状况,提出了一套基于zigbee技术的公路监控系统的设计方案,并给出了软件和硬件的具体实现,伴随着我国公路的大量建设及使用,相信本监控系统必将具有很强的实用价值和广阔的市场应用前景。     

无线传感器网络节点定位技术

无线传感器网络（Wireless Sensor Network,WSN）在许多领域有广泛的应用,无线传感器网络中节点位置对无线传感器网络的应用有重要的影响,没有位置属性的信息是无价值的,定位技术是无线传感器网络的重要研究方向之一.依据测距和非测距的分类方法,介绍节点定位技术的基本原理和方法及当前的发展状况,最后对节点定位技术的发展方向作展望.     

一种适用于无线传感器通信的UWB收发机结构

论文介绍了一种使用低速率超宽带技术实现的适用于无线传感器网络通信的收发机结构,这种结构采用结构简单的IR-UWB(Impulse Radio UWB)方法,能满足无线传感器节点低功耗、低硬件复杂度的要求。这种结构发射机采用SRD(Step Recovery Diode)二极管来产生UWB脉冲信号,接收机则使用结构简单的能量检测方法。     

Positioning of Base Stations in Wireless Sensor Networks

Wireless sensor networks (WSN) have attracted much attention in recent years due to their potential use in many applications such as border protection and combat field surveillance. Given the criticality of such applications, maintaining a dependable operation of the network is a fundamental objective. However, the resource-constrained nature of sensor nodes and the ad hoc formation of the network, often coupled with an unattended deployment, pose non-conventional challenges and motivate the need for special techniques for dependable design and management of WSN. In this article, we highlight the potential of careful positioning of the base station (BS), which acts as a sink node for the collected data, as a viable means for increasing the dependability of WSN. We categorize published work on optimal positioning of BS in WSN. Referring to such work as static positioning, we further introduce dynamic schemes that reposition the BS during the network operation. We show that dynamic BS positioning can be very effective in optimizing the network functional and non-functional performance objectives and in coping with dynamic changes in the environment and available network resources     

无线传感器网络隐私保护方法

如何保护隐私信息在无线传感器网络的应用过程中不被泄露,同时能得到较为准确的结果,是无线传感器网络面临的重大挑战。近年来国内外学者对无线传感器网络的隐私保护技术进行了很多研究,从位置隐私保护和数据隐私保护两方面,总结了现有的隐私保护方法,分析了其基本原理和特点。针对现有方法的不足,本文提出了一种能同时保护位置隐私和数据隐私的隐私保护方法,该方法基于多节点幻影路由技术和椭圆曲线同态加密技术。与现有技术相比,该方法具有更好的隐私保护性和更低的能量消耗性。     

Design of RF transceivers for wireless sensor networks in hazardous applications

Wireless sensor networks (WSN) have a great prospect in many applications, among which the monitoring of hazardous environments is becoming more and more important. The basic requirements of WSN design are low cost and low power consumption, and then a low-power system-on-chip implementation is an optimal solution for WSN nodes. However, the radio-frequency (RF) part of a node chip is usually power hungry and difficult to fully integrate, so many previous works have focused on the design of RF transceivers for WSN. Specifically, for hazardous applications, the communication range is required to be long enough to protect human from harmful environments. So a long effective communication distance is also necessary for WSN transceivers in hazardous applications. In this paper, we give a survey and a classification of WSN transceivers. Furthermore, we analyze the advantages and disadvantages of three main WSN transceivers, i.e. on-off keying transceivers, ultra-wide band transceivers, and frequency shift keying transceivers; and then find out the one most suitable for hazardous applications.     

UWB技术在无线传感器网络中的应用

通信技术的发展推动了无线传感器网络技术的发展,以低功耗为显著特点的UWB技术的出现,更是把现代通信技术推向新的发展高度.文章介绍了无线传感器网络的结构及特点,并结合UWB技术的特点,分析了UWB技术应用于无线传感器网络的优势,同时给出了应用的基本模型结构.     

Implementation of Thermoelectric Generators in Airliners for Powering Battery-Free Wireless Sensor Networks

In recent years, wireless sensor networks (WSN) have been considered for various aeronautical applications to perform sensing, data processing and wireless transmission of information, without the need to add extra wiring. However, each node of these networks needs to be self-powered. Considering the critical drawbacks associated with the use of electrochemical energy sources such as narrow operating temperature range and limited lifetime, environmental energy capture allows an alternative solution for long-term, deploy and forget, WSN. In this context, thermoelectricity is a method of choice considering the implementation context. In this paper, we present hands-on experience related to on-going implementations of thermoelectric generators (TEG) in airliners. In a first part, we will explain the reasons justifying the choice of ambient energy capture to power WSN in an aircraft. Then, we will derive the general requirements applying to the functional use of TEG. Finally, in the last section, we will illustrate the above issues through practical implementations.     

信号强度和运动向量结合的无线传感器网络移动节点定位

无线传感器网络的定位是近年来无线传感器网络研究的重要课题.本文首先介绍了无线传感器网络的来源、重要性以及无线传感器网络定位的分类.然后提出了一种全新定位算法,信号强度和运动向量结合的无线传感器网络移动节点定位,简称SSMV算法,在外围布置四个锚节点,得用信号强度和未知节点在运动中向量的变化,对锚节点在内的未知节点进行定位,并对该算法进行了仿真和总结.通过与凸规划法进行比较,仿真结果表明,该算法有更高的定位精度.     

簇式传感器网络的可认证动态密钥管理方案

Secure sensor networks has received much attention in the last few years. A sensor network always
works unattended possibly in a hostile environment such as a battlefield. In such environments, sensor networks are subject to node capture. Constrained energy,memory, and computational capabilities of sensor nodes mandate a clever design of security solutions to minimize overhead while maintaining secure communication over the lifespan of the network. In this paper, an authenticated dynamic key management scheme, ADKM has been proposed. It provides efficient, scalable, and survivable dynamic keying in a clustered sensor network with a large number of sensor nodes. ADKM employs a combinatorial exclusion basis system (EBS) for efficiency and one-way hash chains for authentication. Analysis of security and performance demonstrate that ADKM is efficient in security of sensor networks.     

Photonic Generation of Ultrawideband Signals

Ultrawideband (UWB) that is regulated by the Federal Communications Commission (FCC) for short-range high-throughput wireless communication and sensor networks with advantageous features, such as immunity to multipath fading, extremely short time duration, being carrier free, and having low duty cycle, wide bandwidth, and low power spectral density, has been a topic of interest recently. By wireless transmission, UWB communications systems can only operate in a short distance of a few meters to tens of meters. The convergence of UWB and optical fiber distribution techniques, or UWB over fiber, offers the availability of undisrupted service across different networks and eventually achieves high-data-rate access at any time and from any place. To distribute the UWB signals over the optical fiber, it is also desirable that the UWB signals can be generated in the optical domain without having extra electrical-to-optical conversion. In addition, UWB signals that are generated in the optical domain can be easily tailored to have a spectrum that meets the FCC-specified spectral mask. In this paper, techniques to generate UWB signals in the optical domain will be discussed. These techniques are divided into three categories, with the generation of UWB signals based on the following: 1) phase-modulation-to-intensity-modulation conversion; 2) a photonic microwave delay-line filter; and 3) optical spectral shaping and dispersion-induced frequency-to-time mapping. The areas for future development and the challenge of implementation of these techniques for practical applications will also be discussed.     

J-Sim: a simulation and emulation environment for wireless sensor networks

Wireless sensor networks have gained considerable attention in the past few years. They have found application domains in battlefield communication, homeland security, pollution sensing, and traffic monitoring. As such, there has been an increasing need to define and develop simulation frameworks for carrying out high-fidelity WSN simulation. In this article we present a modeling, simulation, and emulation framework for WSNs in J-Sim - an open source, component-based compositional network simulation environment developed entirely in Java. This framework is built on the autonomous component architecture and extensible internetworking framework of J-Sim, and provides an object-oriented definition of target, sensor, and sink nodes, sensor and wireless communication channels, and physical media such as seismic channels, mobility models, and power models (both energy-producing and energy-consuming components). Application-specific models can be defined by subclassing classes in the simulation framework and customizing their behaviors. We also include in J-Sim a set of classes and mechanisms to realize network emulation. We demonstrate the use of the proposed WSN simulation framework by implementing several well-known localization, geographic routing, and directed diffusion protocols, and perform performance comparisons (in terms of the execution time incurred and memory used) in simulating WSN scenarios in J-Sim and ns-2. The simulation study indicates the WSN framework in J-Sim is much more scalable than ns-2 (especially in memory usage). We also demonstrate the use of the WSN framework in carrying out real-life full-fledged Future Combat System (FCS) simulation and emulation.     

Position and hop-count assisted full coverage control in dense sensor networks

In recent years, wireless sensor networks (WSN’s) have gained much attention due to its various applications in military, environmental monitoring, industries and in many others. All these applications require some target field to be monitored by a group of sensor nodes. Hence, coverage becomes an important issue in WSN’s. This paper focuses on full coverage issue of WSN’s. Based on the idea of some existing and derived theorems, Position and Hop-count Assisted (PHA) algorithm is proposed. This algorithm provides full coverage of the target field, maintains network connectivity and tries to minimize the number of working sensor nodes. Algorithm works for communication range less than root three times of sensing range and it can be extended for arbitrary relation between communication range and sensing range. By using hop-count value, three-connectivity in the network is maintained. Also, neighbors information is used to create logical tree structure which can be utilized in routing, redundant data removal and in other areas. Simulation results show that PHA algorithm outperforms layered diffusion-based coverage control algorithm by providing better area coverage and activating fewer nodes.     

基于超宽带的无线传感器网络研究与应用分析

无线传感器网络的广泛应用对其物理层性能提出了更高的要求,UWB技术由于低功耗、定位精度高等特点成为无线传感器网络体系结构设计中物理层的候选协议。本文介绍了UWB应用于无线传感器网络物理层的研究与应用现状。