Hydrogen‐Gas Detection System and its Functions to Make Each Sensor Wireless

A prototype system for detecting hydrogen‐gas leaks in hydrogen filling stations was fabricated. The prototype is composed of a wireless network with 10 sensor nodes for monitoring the spatial distribution of hydrogen‐gas concentration. To make each sensor node to be driven by a battery, field‐effect transistor (FET) sensors and a microprocessor with low power consumption were used. Additionally, two functions were devised and implemented in the microprocessor in each node: one reduces the power consumption of each sensor node and the other controls the transmission to avoid communication congestion when a gas leak occurs. The use of batteries and wireless communications enables the nodes to be placed at optimal sensing locations without regard to the wiring needed with existing gas sensors. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Deployment control of wireless multihop‐relay mobile robots based on voronoi partition

This paper describes a new method for the deployment of wireless relay nodes. When using rescue robots in a building or underground city, radio signals are attenuated significantly, and therefore, multihop extension involving wireless communication relays is required. The goal of this research is to deploy wireless relay nodes to maintain connectivity between the base station and the leader robot that explores around the front line. To move the relay robot autonomously, a distributed algorithm is required. The proposed method is suitable when it is applied for wireless relay purposes. In this method, a virtual force drives a node to the centroid of Voronoi neighbors so that the connectivity of wireless communication is maintained. The proposed method is evaluated by conducting numerical simulations and experiments. In the simulation, one or two leader robots are assumed. In the experiment, a mobile robot equipped with omni‐wheels is used. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(4): 42–51, 2013; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22413     

面向协作通信的忙音信道接入机制

与传统无线传输相比,虽然协作中继节点的参与可以大大提高无线网络性能,然而协作中继会带来严重的信道竞争问题,这给协作通信环境中的信道访问控制带来挑战。为了解决这个问题,提出一种RTS/CTS(Request To Send/Clear To Send)与忙音结合的MAC(media access control)信道接入方案。该方案使用3个忙音来标识信道的使用状态,并解决协作通信中的隐藏终端和暴露终端问题。基于忙音信号,还提出了一种带宽节俭的协作节点选择算法。通过侦听忙音信号,源节点可分布式地选择最优的协作节点。理论分析和仿真实验表明所提方案能有效地提高协作通信中的信道利用率,很好地解决了协作通信中的隐藏终端暴露终端问题。在数据包大小超过3 500 B时,本协议中暴露终端受传输节点阻塞的时间不到整个传输时间的10%。     

基于无线通信和光通信的高压输电线路监测系统

提出一种高压输电线路监测系统方案,该系统由安装在输电线路铁塔上的无线监测节点、光通信节点以及电力特种光缆中的空闲纤芯组成。这些无线节点和光节点通过AdHoc组网方式构成具有自适应功能的基础通信网络,通过无线接力传输和光信号接力传输相结合的方式,实现监控中心与任意监测节点之间的双向信息交互。该系统可以对复杂地形条件下的长距离输电线路进行全程、逐塔的实时监测,还可以支持工作人员在输电线路延线的邻近区域内,利用专用无线终端接入监测网络,进行语音、数据、视频的双向通信,为线路检修和抢险救灾等特殊场合提供应急通信手段。     

放大转发双向中继网络的总速率最大化

在一个双向中继网络中,2个终端在中继节点的帮助下,通过一个共享的半双工无线信道进行信息交换,它能够增大系统单位时间的吞吐量,放大转发的双向中继网络就是其中的一种形式,该模型因为它的简单易用而受到关注,并在无线网络通信中得到了广泛的运用。本文研究如何在达到最大速率传输的同时,系统的传输可靠性相对达到最大。     

一种用于多信道无线Mesh网络的信道分配方法

合理地分配信道是提高多信道无线Mesh网络性能的关键。针对动态信道分配策略平均吞吐率较低的不足,采用相对平衡理论,提出了一种基于可通邻居节点可用信道表的信道分配方法,给出了该方法的主要步骤和具体实现过程,并分析了时间复杂度。节点在进行数据发送前,利用可通邻居节点的可用信道集合,建立可通邻居节点可用信道表和信道优先级队列,在此基础上,选取一个最优信道,并使用改进的RTS/CTS协议进行信道协商和数据收发控制。仿真结果表明,提出的方法在平均吞吐率方面提高了5.2%。     

高速无线芯片原型系统设计与实现

面对宽带高速无线芯片原型系统设计的实现目的,采用信号完整性方法,提出并实现了一个基于FPGA和ARM的高速无线芯片原型系统。该系统集成了高速无线芯片原型系统所需的完备设计资源。整个系统在围绕验证无线传输芯片原型系统上做出了全面配置,在电源、时钟、DDR等方面做了专门考虑和优化。实际测试结论表明,该原型系统所具备的高性能、可配置、可重构的特性,相对传统平台功配置更灵活、设计反复时间减少。     

电力线和无线双媒质通信系统的自适应中继协议

综合考虑混合媒质通信和中继协作技术,研究了无线移动接入、无线和电力线并行传输的系统.利用多维对数正态近似算法以及终端信噪比的矩生成函数,分别推导出系统采用放大前传(AF)和译码前传(DF)时中断概率的闭合解析式;为了有效克服AF和DF中继协议的缺点,提出了自适应中继协议,即根据信道通信质量动态选择AF或者DF中继协议,并给出了具体的实现步骤;最后采用蒙特卡洛仿真验证了理论分析的有效性和可靠性.理论和仿真结果表明,与AF和DF中继协议相比,所提出的自适应中继协议在低信噪比区域和高信噪比区域均能获得较好的通信质量.     

Feasibility study on a highly mobile microwave-band broad-bandtelecommunication system

A prototype of a wireless transmission system has been developed that can transmit multimedia-information data at a maximum rate of 4.608 Mb/s in the 5.2-GHz carrier frequency band. It is based on a multicode transmission scheme that uses cyclic shifted-and-extended M-sequences and is designed for applications such as intelligent transport systems (ITS) and future broadband mobile communication systems. The proposed scheme is highly robust against high-speed multipath fading. The transmission performance of the prototype system was measured in field trials at an outdoor ITS experimental course. The real-time data-transmission rate between the base and mobile stations was 4.608 Mb/s at a vehicle speed of 80 km/h     

基于无线公网和ZigBee无线传感器网络技术的输电线路综合监测系统

以无线公网(GPRS/CDMA)和ZigBee无线网络通信技术为基础研发了一套输电线路综合监测系统,该系统把与输电线路相关的各个监测硬件单元分别设计为独立的无线传感器节点,利用无线传感器网络进行数据收集,并通过无线公网把数据传回监测中心。文章详细阐述了监测主机以及用于监测弧垂、输电线温度和绝缘子的无线传感器节点的硬件结构和工作流程。采用ZigBee无线网络技术使得输电线路综合监测系统具有良好的可扩展性、可靠性和安全性,并且便于维护,功耗较低。     

Development of a time‐synchronized wireless sensor network

Network‐based wireless sensing has become an important area of research and various new applications for remote sensing are expected to emerge. One of the promising applications is structural health monitoring of buildings or civil engineering structures, which often requires vibration measurement. For vibration measurement via a wireless network, time synchronization is indispensable. In this paper we introduce a newly developed time‐synchronized wireless sensor network system. The system employs an IEEE 802.11 standard‐based TSF counter and sends the measured data with the counter value. It makes possible consistency on a common clock among different wireless nodes. We describe the accuracy evaluation by simulation studies as the size of the nodes is increased. The hardware and software specifications of the developed wireless system are presented. The experiments were conducted in a three‐story reinforced concrete building and the results showed that the system performance significantly exceeds requirements. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(4): 46–53, 2010; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21020     

High‐throughput selective cooperation with complex field network coding in multiuser networks

In this paper, a cooperation system suitable for networks with multiple users is proposed. In the first phase of the cooperation, the user who has correctly decoded the source signal and has the best channel condition is selected as the relay. Given that the best relay selected by one source–destination (s‐d) pair may also be selected by other pairs, complex field network coding (CFNC) is adopted by the relay in the second phase, to provide diversity gains for the s‐d pairs simultaneously. The number of channels used is reduced, thus increasing the network throughput. Additionally, this system makes up for the performance loss of the traditional CFNC cooperation in large‐scale networks by achieving more diversity gains. Especially, a closed‐form expression of the average signal error probability (SEP) is derived for small‐scale networks, while an upper‐bound estimation is given for larger networks. It is demonstrated that the system achieves full diversity and is robust. To improve the SEP performance of the system, the receiver is modified, and the results demonstrate desirable average SEP performance. Finally, the analytical results are validated by numerical simulations. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

多跳AF中继中的动态混合携能通信

考虑从信源到信宿经过m跳的多跳AF中继传输,给出了混合时间分配和功率切割的无线携能通信协议的帧结构构建过程。在每个中继的总传输功率和吞吐量一定的约束条件下,评估了功率传输效率和信息传输性能之间的权衡关系。导出了双参数混合的非闭合形式表达式,计算出在给定节点吞吐量下的最大可实现跳数。数值仿真结果表明,为了扩展网络覆盖范围和保证能源效率,可以通过不同的中继跳数动态调整两个参数,以实现最佳的无线携能通信性能。     

感知策略下的无线传感网络保密容量问题研究

无线传感器网络(WSN)指的是由可以感知和检查外部世界的传感器组建而成的分布式无线网络。得益于硬件系统的飞速发展,无线传感网络广泛应用到了军事、智能交通、环境监控、医疗卫生等多个领域。考虑到无线传感器受限于能量,计算能力等诸多因素,其引发出来的无线传感网络通信安全问题成为了一大研究热点。本文旨在探讨如何应用压缩感知技术保证无线传感网络的安全通信,针对放大转发式压缩感知技术下的无线传感网络安全保密问题推导给出了可计算的保密容量门限值。最后分别讨论了不同数目下的活跃感知节点,中继节点以及窃听节点对无线传感网安全保密容量的影响。仿真结果进一步验证了所推导的保密容量结论。     

慈溪电力应急指挥通信系统的建设

在国家电网公司应急指挥通信系统规划设计的背景下,慈溪供电局结合自身需求组织搭建了一套基于宽带无线专网的应急指挥通信系统。该系统由区域传输网络和指挥调度平台两部分组成。其无线传输网络通过4个基站,结合终端中继实现了全市范围的无线信号覆盖,具备语音、视频及IP数据等综合业务传输能力。系统具有实用性强、业务兼容性好、扩展能力强及数据安全性高等特点。     

无人机辅助无线通信位置和波束联合优化方法

无人机辅助无线通信具有部署灵活,覆盖范围大等优势,但仍存在路径损耗大,吞吐量和传输能力低的缺点。将波束赋形技术引入无人机辅助无线通信中,可以有效补偿通信路径损耗,缓解小区内或小区间干扰。因此,本文面向无人机辅助无线通信系统,在地面基站和无人机上配备均匀平面阵列来实现波束赋形,以最大化系统容量。针对优化变量高维且高度耦合的非凸问题,提出了一种高效迭代算法来联合优化中继无人机位置和波束赋形向量,首先通过块坐标下降法将原问题转化为中继无人机位置优化和波束赋形向量优化两个子问题,然后利用连续凸逼近算法将两个子问题转化为凸优化问题进行求解。实验结果表明,所提的优化理论和算法具有较好的收敛性能,并且能够切实提高系统容量。     

IEC 61850应用于分布式馈线自动化系统的模型

远传型故障指示器或功能模块可以检测配电线路各区段的故障并上传检测结果,从而为分布式馈线自动化(FA)进行故障区间定位提供判断依据。以IEC 61580-90-6技术报告所提出的故障指示功能为基础,构建基于IEC 61850的分布式馈线自动化的系统模型,提出了分布式故障区间定位、隔离和供电恢复的逻辑节点。扩展现有的IEC 61850系统配置语言(SCL)模型以描述配电网的一次拓扑和逻辑功能配置。给出IEC 61850应用于馈线自动化系统的通信服务映射。最后,提出了变电站自动化和馈线自动化系统进行数据交换的配置流程。通过应用示例表明,所提出的IEC 61850信息模型可以支持分布式馈线自动化功能和终端之间的互操作。     

Low‐latency retransmission control in a wireless communication system for plant instrumentation and control

When wireless communication technology is applied to plant instrumentation and control systems, it is important to ensure real‐time transmission and high reliability of the wireless communication system. However, the wireless communication system is prone to more frequent occurrence of transmission errors than a wired communication system, so that generally retransmission is implemented generically. To reduce retransmission latency, we propose a method of low‐latency retransmission control, which is a data block transmission method with multi‐redundant media access control layer (MAC) headers, to implement a wireless communication system for plant instrumentation and control. We carried out system tests using prototypes with the proposed methods, that is, data block transmission with multi‐redundant MAC headers. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

混合WSN中的单层约束中继节点放置研究

针对混合无线传感器网络中的中继节点放置问题,提出了一种满足一定的连通性和生存性要求的最小数量中继节点放置算法,其中中继节点只能放置到候选位置的一个子集上。在连接中继节点的放置问题中,提出一种采用基于最小生成树的STP高效近似算法,以保证传感器节点和基站之间的连通性;在可生存中继节点的放置问题中,提出了基于{0,1,2}-SNDP的多项式时间近似算法,以保证传感器节点和基站之间的双连通性。实验结果表明,单层约束中继节点放置算法具有较小的运行时间和几乎可以达到与最优解结果相媲美的性能.