A New Method to Improve Performance of Cooperative Underwater Acoustic Wireless Sensor Networks via Frequency Controlled Transmission Based on Length of Data Links

In this paper a new method to improve performance of cooperative underwater acoustic (UWA) sensor networks will be introduced. The method is based on controlling and optimizing carrier frequencies which are used in data links between network nods. In UWA channels Pathloss and noise power spectrum density (psd) are related to carrier frequency. Therefore, unlike radio communications, in UWA Communications signal to noise ratio (SNR) is related to frequency besides propagation link length. In such channels an optimum frequency in whole frequency band and link lengths cannot be found. In Cooperative transmission, transmitter sends one copy of transmitted data packets to relay node. Then relay depending on cooperation scheme, amplifies or decodes each data packet and retransmit it to destination. Receiver uses and combines both received signals to estimate transmitted data. This paper wants to propose a new method to decrease network power consumptions by controlling and sub-optimizing transmission frequency based on link length. For this purpose, underwater channel parameters is simulated and analyzed in 1km to 10km lengths (midrange channel). Then link lengths sub categorized and in each category, optimum frequency is computed. With these sub optimum frequencies, sensors and base station can adaptively control their carrier frequencies based on link length and decrease network’s power consumptions. Finally Different Cooperative transmission schemes “Decode and Forward (DF)” and “Amplify and Forward (AF)”, are simulated in UWA wireless Sensor network with and without the new method. In receiver maximum ratio combiner (MRC) is used to combining received signals and making data estimations. Simulations show that the new method, called AFC cooperative UWA communication, can improve performance of underwater acoustic wireless sensor networks up to 40.14%.

A Study on Vehicle Detection and Tracking Using Wireless Sensor Networks

Wireless Sensor network (WSN) is an emerging technology and has great potential to be employed in critical situations. The development of wireless sensor networks was originally motivated by military applications like battlefield surveillance. However, Wireless Sensor Networks are also used in many areas such as Industrial, Civilian, Health, Habitat Monitoring, Environmental, Military, Home and Office application areas. Detection and tracking of targets (eg. animal, vehicle) as it moves through a sensor network has become an increasingly important application for sensor networks. The key advantage of WSN is that the network can be deployed on the fly and can operate unattended, without the need for any pre-existing infrastructure and with little maintenance. The system will estimate and track the target based on the spatial differences of the target signal strength detected by the sensors at different locations. Magnetic and acoustic sensors and the signals captured by these sensors are of present interest in the study. The system is made up of three components for detecting and tracking the moving objects. The first component consists of inexpensive off-the shelf wireless sensor devices, such as MicaZ motes, capable of measuring acoustic and magnetic signals generated by vehicles. The second component is responsible for the data aggregation. The third component of the system is responsible for data fusion algorithms. This paper inspects the sensors available in the market and its strengths and weakness and also some of the vehicle detection and tracking algorithms and their classification. This work focuses the overview of each algorithm for detection and tracking and compares them based on evaluation parameters.

A synchronous duty-cycled reservation based MAC protocol for underwater wireless sensor networks

To design an energy-efficient Medium Access Control(MAC)protocol for the Underwater Wireless Sensor Networks(UWSNs)is an urgent research issue since depleted batteries cannot be recharged or replaced in the underwater environment.Moreover,the underwater acoustic channels are affected by hindrances such as long propagation delay and limited bandwidth,which appear in the design of the MAC protocol for the UWSNs.The available MAC protocols for the terrestrial wireless sensor networks exhibit low performance in energy efficiency,throughput and reliability in the UWSNs,and cannot be used in the UWSNs directly because of their unique characteristics.This paper proposes a synchronous duty-cycled reservation-based MAC protocol named Ordered Contention MAC(OCMAC)protocol.The basic mechanism of this protocol is to schedule data transmission by transmitters through the scheduling of Ready To Send(RTS)frames.The protocol eliminates the possible collision during data transmission and improves communication efficiency.The paper analyzes the performance in energy efficiency,throughput and reliability of the protocol by modeling the queuing behavior of OCMAC with a Markov Chain process.Furthermore,the analytical model is validated through a simulation study.The analysis results demonstrated that while providing good throughput and reliability,OCMAC can achieve energy saving.

A Design of Acoustic Signal Wireless Acquisition System for Stored Grain Pests Based on Compressed Sensing

In order to achieve the acoustic signal distributed acquisition of stored grain pests, a novel acoustic signal acquisition system was presented based on the wireless sensor networks. And the system architecture, hardware configuration, and software were introduced in detail. Considering bandwidth limitation of wireless sensor networks, random sampling algorithm based on the compressed sensing theory was proposed. The developed acoustic signal acquisition system was applied in sampling the crawl acoustic signal of Tribolium castaneum Herbst adults in granary. Preliminary experimentation indicated the rationality and practicability of the developed system and the proposed algorithm. They can implement the remote, real-time, and reliable wireless transmission for the acoustic signal sampled data of multiple points stored grain pests effectively.

An Acoustic Modem Featuring a Multi-Receiver and Ultra-Low Power

Wireless technology for underwater communication possesses a wide range of potential application, but it is still a relatively unexplored area in many aspects concerning modems physical design. A step towards future deployment of underwater networks is the reduction of power consumption. Therefore, asynchronous wakeup systems need to be integrated within the physical layer design while avoiding the use of additional transducers. This paper offers a practical and generic solution to adapt data reception and transmission together with asynchronous wakeup sub-systems in acoustic underwater modem architectures using a low power and low cost solution. The proposal has been implemented in a real prototype with success.

Compressive sensing in wireless sensor network for poultry acoustic monitoring

A wireless acoustic sensor network was realized using wireless sensor nodes equipped with microphone condensers,in which its sensor nodes were configured to capture poultry sound data and transmit it via the network to a collection point.A high performance computer can process these large volumes of animal audio signals under different behaviors.By performing data signal processing and analyzing the audio signal,poultry sound can be achieved and then transformed into their corresponding behavioral modes for welfare assessment.In this study,compressive sensing algorithm was developed in consideration of the balance between the power saving from compression ratio and the computational cost,and a low power consumption as well as an inexpensive sensor node was designed as the elementary unit of poultry acoustic data collecting and transmission.Then,a Zigbee-based wireless acoustic sensor network was developed to meet the challenges of short transmission range and limited resources of storage and energy.Experimental results demonstrate that the compressive sensing algorithm can improve the communication performances of the wireless acoustic sensor network with high reliability,low packet loss rate and low energy consumption.

水下无线传感器网络自适应锥体矢量路由协议

水声传感器网络(Underwater Acoustic Wireless Sensor Networks,UWSNs)由于复杂的水下环境,面临着投递率低、传播延迟高和节点能耗大等挑战。为解决这些问题,文章提出了一种自适应锥体矢量路由协议(Adaptive Cone Vector Routing Protocol,ACVRP),根据节点密度自适应调整锥体区域大小和方向,减少冗余通信和网络能耗,并根据节点的剩余能量和节点在锥体区域中的位置确定节点转发优先级,以提高投递率、减少传输跳数。仿真实验结果显示,与VBF、AHH-VBF和AHHC-VBF相比,ACVRP在包投递率、能效和端到端延迟方面均表现更佳。

水下无线传感器网络抗恶意干扰技术应用及研究进展

水下无线传感器网络(UWSNs)越来越广泛地应用于海洋开发等领域,但其水声通信信道的开放性导致UWSNs容易受到水下的各类恶意干扰,各类通信抗干扰技术可有效提高UWSNs的通信可靠性。文中首先介绍了通信抗干扰技术的发展历程及其国内外发展现状,并对通信抗干扰技术的发展规律进行分析;其次分析了UWSNs中通信抗干扰的关键技术以及技术需求,最后对UWSNs通信抗干扰技术的发展应用进行了展望。

分布式平均共识的无线声传感器网络时钟校准

在无线声传感器网络中,每个节点的时钟系统通常独立,受制造工艺、温度、湿度等因素的影响,各节点间的时钟存在异步问题。时钟校准方法是补偿节点间的采样率偏差的有效手段。然而,大部分已有方法只能以集中式的方式适用于无线声传感器网络中,这不仅需要额外的中心处理单元,也将带来较重的通信负担。针对上述问题,本文提出一种无线声传感器网络时钟校准方法。首先,在线性相位漂移模型中引入解卷绕策略,以消除高频处的相位模糊问题,进而提高每对相邻节点间的时钟同步精度。接着,基于分布式平均共识算法,提出一种分布式时钟校准新方法,使各节点并行地、协作地进行时钟同步。其次,在补偿各节点采样率偏差的基础上,仅利用到达时间信息进行分布式声源定位。最后,根据声源位置,分布式地估计各节点之间的起始采样偏差。与已有方法不同,所提方法仅需相邻节点之间的局部通信、无须中心处理单元、鲁棒性强,更适用于无线声传感器网络。本文实验结果表明了该方法的有效性。

基于无线传感器网络的粮虫声信号采集系统设计

为了解决现有储粮害虫声信号采集系统存在的扩展性差、智能化程度不高、性价比较低、灵活性不强、数据传输能力较弱等问题,该文分析了现有储粮害虫声信号采集系统存在的局限性,在此基础上,利用无线传感器网络和压缩感知技术,设计了一种新型储粮害虫声信号采集系统,给出了系统结构和软硬件实现方法,并将其用于采集储粮罐内赤拟谷盗成虫的爬行声。试验结果表明,系统设计方案合理可行,且由于使用了压缩感知技术,在采样频率为10KHz的情况下,可实现20个采集节点所产生的声信号原始采样数据的远程、实时、可靠无线传输。该研究为无线传感器网络在储粮害虫防治中的应用做出了探索。

基于作物水分胁迫声发射技术的无线传感器网络精量灌溉系统的初步研究

为实现准确判断作物水分亏缺程度,为精量灌溉提供科学依据,该文基于作物水分胁迫声发射技术,研发了无线传感器网络节点,并设计了无线传感器网络精量灌溉系统。该系统可以使人们随时随地精确获取作物需水信息,并实现精量灌溉。该系统具有功耗低、成本低廉、鲁棒性好、扩展灵活等优点。初步试验表明了该系统的合理性与实用性。可以应用于温室、农田、苗圃等区域。该研究为无线传感器网络在节水农业中的应用做出了探索。

基于无线声阵列传感器网络的实时多目标跟踪平台设计及实验

介绍了一套自主开发和实现的无线声阵列传感器网络多目标跟踪平台。在相关的多目标跟踪技术的基础上,结合无线声阵列传感器网络的特点,对系统平台的工作流程进行了整体设计并实现了相关算法模块,并在该平台下进行了多目标跟踪实验。实验中利用随机部署在实验区域中的多个声阵列传感器实现了对多个目标实时跟踪,同时还根据实验数据的分析建立了多目标下声阵列传感器的量测模型,并展示了平台下多目标跟踪实验的总体效果及各支撑模块的性能分析。实验表明该平台的设计达到预期要求,是无线声阵列传感器网络在多目标跟踪领域的前沿研究和实践。

用于驱赶农作物有害动物的智能声防系统设计

针对农业生产中动物有害行为导致农作物减产和农产品价值严重损失的实际问题,设计研发出一种驱赶农作物有害动物的智能声防系统。该系统以无线传感器网络作探测和通信平台,采用以ARM9微处理器和AT89C51SND1单片机为核心的嵌入式系统构建总控制器和执行器硬件平台,通过热释电传感器对有害动物在农田中的出没位置进行探测,依据"作物种类-周围环境-有害动物-天敌"逻辑关系模型对其种类作出判断,然后由执行器播放该种动物对应天敌的叫声,从而实现对多种农作物有害动物的智能声防。与现有的驱赶模式易被有害动物适应且效果不佳相比,该系统具有驱赶效果好、有效作用面积大、可扩展性强及装设灵活等优点,是一种无污染、具有智能特性的驱赶农作物有害动物的有效解决方案。

水声传感器网络及其在海洋监测中的应用研究

针对海洋监测水声传感器网络中的基础性问题,分析和总结了近年来相关的主要研究方向和重要研究成果。同时,深入讨论了海洋监测水声传感器网络研究所面临的挑战和亟须解决的问题,为今后的研究提供了方向。

基于声学无线传感器网络的目标跟踪系统研究

利用无线传感器网络对具有声音特性的目标进行跟踪的特点,研究了基于时延估计的声源定位方法。选择广义互相关法作为时延估计算法,并改进球形插值法用于声源定位,从而减小了算法复杂度;再利用IRIS节点设计了一个面向目标跟踪的声学无线传感器网络原型系统,并进行相应的实验。实验结果表明,利用所设计的原型系统能实现对移动目标跟踪,而且跟踪精度较高。

无线传感器网络中基于移动智能体的目标追踪

就无线传感器网络中的目标追踪问题而言,减少传感器之间的冲突、提高追踪精度是两个重要问题．为此,采用移动智能体方法协同声音传感器追踪移动目标．当目标出现时,负责追踪的智能体产生,并随目标移动而移动．为减小在选举移动智能体的过程中出现的冲突,采用基于概率的选举策略,给出概率函数的设置方法．在目标关联过程中,时间窗口的大小对算法的追踪精度而言至关重要,经过分析,给出了设置时间窗口大小的基本原则．仿真结果表明设计恰当的随机函数和时间窗口可以有效地减小冲突、提高追踪的精度．

水声通信网综述

近年来,由于水下通信技术的发展和应用需求,国内外对水声通信网络进行了大量的研究工作,并且在方案验证、模拟仿真的基础上,开始了水声网络的海上实验。本文从水声通信网的发展过程和特点出发,系统介绍了水声通信网的体系结构和关键技术,并且详细介绍了各层的研究内容和研究现状,最后对水声通信网今后的研究方向和应用前景进行了展望。

基于声强的无线传感器网络目标跟踪方法研究

为有效解决无线传感器网络对具有声音特性移动目标的跟踪问题,该文利用声音随距离的能量衰减模,并结合声强特性,给出了基于动态组管理机制的目标跟踪方法。仿真实验结果表明无线传感器网络中基于声强特性的方法,能够有效实现对移动目标跟踪,结合Kalman滤波算法提高了实验结果的跟踪精度。