Half‐duplex visible light communication using an LED as both a transmitter and a receiver

In typical visible light communication (VLC) systems, light‐emitting diodes (LEDs) are used as optical transmitters and photodiodes are used as optical receivers. Currently, many communication devices such as smart phones have a built‐in LED lamp whereas they usually do not have a built‐in photodiode. If we find a way to receive VLC signals without the need to add an additional photodiode on the communication devices, it will contribute to the spread of VLC. Therefore, we propose and demonstrate a VLC scheme without the need for a photodiode. As the first step, we investigate the characteristics of an LED as a VLC receiver and find out that an LED can also be used as a VLC receiver in certain conditions. Then, we demonstrate a half‐duplex VLC system using an LED as both an optical transmitter and an optical receiver, without the need for a photodiode. This technique could be used in various applications such as the VLC between smart phones with a built‐in LED lamp and the VLC between LED traffic lights. Copyright © 2015 John Wiley & Sons, Ltd.     

荧光LED通信系统线性失真测量及其补偿

为了改善线性失真对荧光LED通信系统性能的影 响,首先建立了通信实验系统, 采用网络分析仪测量了通信系统的幅频响应,分析了线性失真特性。根据通信系统线性失真 的测量结果,设计了一、二、三阶高通滤波器作为线性失真补偿电路,将其与荧光LED通 信系统级联,分别测量了级联后系统的幅频响应。结果显示,采用三阶补偿电路后,荧光 LED通信系统的线性失真得到了明显改善,系统增益的衰减幅度由补偿前的50dB(0.3~6MHz)降低为三阶补偿后的20dB(0.3~45MHz)。为了确保通信系统具有相对平坦的增益 特性且要求系统增益的波动小于10dB时,系统的通频带宽度可从补 偿前的1.8MHz提高到 三阶补偿后的41MHz (范围为3~44MHz),增 大了约23倍,且在此频带范围内,系统具有 相对较大的增益(约为－30dB)。因此,补偿荧光LED通信系统的线 性失真,可以很好扩展通信系统所需的通频带宽度。本文的实验和分析可为进一步优化系 统参数及改进通信性能提供参考依据。     

Design and experimentation of remote driving system for robotic speed sprayer operating in orchard environment

The automation of agricultural machines is an irreversible trend considering the demand for improved productivity and lack of labor in handling agricultural tasks. Unstructured working environments and weather often inhibit a seemingly simple task from being fully autonomously performed. In this context, we propose a remote driving system (RDS) to aid agricultural machines designed to operate autonomously. Particularly, we modify a commercial speed sprayer for orchard environments into a robotic speed sprayer to evaluate the proposed RDS's usability and test three sensor configurations in terms of human performance. Furthermore, we propose a confidence error ellipse-based task performance measure to evaluate human performance. In addition, we present field experimental results describing how the sensor configurations affect human performance. We find that a combination of a semiautonomous line tracking device and a wide-angle camera is the most effective for spraying. Finally, we discuss how to improve the proposed RDS in terms of usability and obtain a more accurate measure of human performance.     

New type of optical fibre analogue SSB data communication system using edge‐emitting LED coupled to single‐mode optical fibre

This paper describes a single‐mode(SM) optical fibre SSB data communication system for use in place of power‐line data transmission. In the optical transmitter, SSB data is fed through the squarewave frequency (SWFM) modulator to the edge‐emitting LED (ELED) module. The light beam of the ELED module is fed to the SM optical fibre having a length of 12km. In the optical receiver, the light beam received through the SM optical fibre is detected by the PIN photodiode module, and fed to the SWFM detector to obtain the double‐pulse frequency modulation (DPFM) signal voltage. The DPFM signal voltage at the output of the SWFM detector is fed to the low‐pass filter (LPF) to obtain analogue SSB data. When the transmission was experimentally carried out, the spurious component was as low as −50–−70 dB and the SNR of SSB data as high as more than 65–70 dB. The optical transmitter and receiver were attached to the conventional analogue SSB data communication system to constitute a new optical fibre analogue SSB data communication system. During the field test utilizing the new system, the crosstalk and SNR were 60–70 dB and 60–70 dB on each channel, respectively. Copyright © 1999 John Wiley & Sons, Ltd.     

工作空间测量定位系统加权问题研究

工作空间测量定位系统(workspace Measuring and Positioning System,简称wMPS)是一种基于旋转激光扫描平面定位技术的室内大尺寸定位系统。它可实现计量精度的三维坐标测量,主要应用于制造加工及装配领域。作为一种分布式系统,工作空间测量定位系统也存在着为不同测量节点分配权重的问题。考虑到在定位过程中误差的复杂性,提出一种根据不同测量区域,利用统计数据对不同测量节点动态分配权重的分权方法。为验证此方法,设计了对比实验,实验结果表明:文中提出的加权方法可显著提高工作空间测量定位系统的测量精度。     

基于HMR3000和nRF905的新型车辆模拟驾驶训练系统动感系统设计

动感系统是新型车辆模拟驾驶训练系统的重要组成部分,它可以增强模拟驾驶训练的真实感,这是新型车辆模拟驾驶训练系统区别于现有车辆模拟驾驶训练系统的独特之处.详细介绍动感系统的总体构想及其软硬件设计.     

气象信息实时监测预警LED显示屏发布系统设计与实现

简要概述大连气象部门LED电子显示屏发布系统的设计与实现,介绍LED屏的分类,屏幕使用过程中的操作步骤,二次开发工作需要注意事项的问题。系统发挥了现有设备的功能,解决业务应用部门实时资料监测显示中相关问题,具有很好的推广价值和业务使用价值。     

An ice machine adapted into an autonomous photovoltaic system without batteries using a variable‐speed drive

The adaptation of a commercially available ice machine for autonomous photovoltaic operation without batteries is presented. In this adaptation a 1040 W_p photovoltaic array directly feeds a variable‐speed drive and a 24 V_dc source. The drive runs an induction motor coupled by belt‐and‐pulley to an open reciprocating compressor, while the dc source supplies a solenoid valve and the control electronics. Motor speed and refrigerant evaporation pressure are set aiming at continuously matching system power demand to photovoltaic power availability. The resulting system is a simple integration of robust, standard, readily available parts. It produces 27 kg of ice in a clear‐sky day and has ice production costs around US$0.30/kg. Although a few machine features might be specific to Brazil, its technical and economical guidelines are applicable elsewhere. Copyright © 2010 John Wiley & Sons, Ltd.     

便携式脉冲调制型医用半导体激光器的驱动电源及光学透镜系统的设计

针对脉冲激光器穴位照射治疗的特点,对半导体激光二极管（LD）的驱动电路及光学镜头系统的设计进行了研究。本文设计了一款新型的锂电池供电便携式脉冲医用激光器,介绍了采用脉冲调制恒流驱动的原理以及采用透镜组和电路调整的方法改变激光照射功率密度的光学镜头的设计方法。该款脉冲激光器适用于激光体外穴位照射,对激光临床应用有一定的意义。     

An amplify‐and‐forward and decode‐and‐forward mixed relay communication system and its performance analysis

A kind of amplify‐and‐forward (AF) and decode‐and‐forward (DF) mixed relay communication system is proposed in this letter. The source broadcasts the signal to all the relays. Relays that can decode the signal adopt DF scheme to retransmit the signal, while the rest adopt AF scheme for retransmission. The destination employs maximum ratio combining technique to maximize the received signal‐to‐noise ratio. Another situation concerned in this letter is that when the relay cannot decode the source signal, it may retransmit the interference signal with AF scheme. Closed‐form expressions of outage probability are derived. Simulation results show that the analytical curves agree with the simulated ones very well, and the AF‐DF mixed relay system can improve the availability of the relays. Copyright © 2013 John Wiley & Sons, Ltd.     

High‐capacity soliton transmission for indoor and outdoor communications using integrated ring resonators

A system consisting of a series of microring resonators, incorporating an add/drop system, is presented in order to create ultra‐short spatial and temporal single and multisoliton pulses, which can be used for indoor and outdoor optical communications. Chaotic noise can be generated by a bright soliton pulse propagating inside a nonlinear microring resonator system. The results obtained show that a single temporal and spatial soliton pulse, with full width at half maximums of 75 fs, 80 fs, 700 fs, 4.4 ps, and 0.30 nm, can be generated. The add/drop system can be used to generate a high number of ultra‐short soliton pulses in the ranges of nanometer/second and picometer/second. The simulated multisolitons have full width at half maximums of 16 ps, 20 pm, 130 ps, and 35 pm and free spectrum ranges of 500 ps, 0.57 nm, 3.5 ns, and 1.4 nm, respectively. The multisolitons generated at the drop port can be used in indoor optical communications, where the ultra‐short pulses with a variety of central wavelengths (from λ = 1550 to λ = 1560) from the through port can be multiplexed‐demultiplexed along an optical fiber with a length of 50 km. The filtered signals can be obtained at the end of the transmission link used for optical outdoor communications. Copyright © 2013 John Wiley & Sons, Ltd.     

Distributed fuzzy logic based energy‐aware and coverage preserving unequal clustering algorithm for wireless sensor networks

In an energy‐constrained wireless sensor networks (WSNs), clustering is found to be an effective strategy to minimize the energy depletion of sensor nodes. In clustered WSNs, network is partitioned into set of clusters, each having a coordinator called cluster head (CH), which collects data from its cluster members and forwards it to the base station (BS) via other CHs. Clustered WSNs often suffer from the hot spot problem where CHs closer to the BS die much early because of high energy consumption contributed by the data forwarding load. Such death of nodes results coverage holes in the network very early. In most applications of WSNs, coverage preservation of the target area is a primary measure of quality of service. Considering the energy limitation of sensors, most of the clustering algorithms designed for WSNs focus on energy efficiency while ignoring the coverage requirement. In this paper, we propose a distributed clustering algorithm that uses fuzzy logic to establish a trade‐off between the energy efficiency and coverage requirement. This algorithm considers both energy and coverage parameters during cluster formation to maximize the coverage preservation of target area. Further, to deal with hot spot problem, it forms unequal sized clusters such that more CHs are available closer to BS to share the high data forwarding load. The performance of the proposed clustering algorithm is compared with some of the well‐known existing algorithms under different network scenarios. The simulation results validate the superiority of our algorithm in network lifetime, coverage preservation, and energy efficiency.     

Revitalization and analysis of operation of the autonomous photovoltaic system of the Uacari Floating Lodging House,Amazon‐Brazil

This paper presents the main problems found in photovoltaic systems in the Amazon Region and the actions to be performed for restructuring and correcting the operation of such systems. These problems and solutions are exemplified on the basis of the diagnosis and revitalization of the 2.5‐kWp photovoltaic installation that belongs to the central module of the Uacari Floating Lodging House. The paper was accomplished as part of the agreement between the Group of Studies and Development of Energy Alternatives (GEDAE) and the Mamirauá Institute of Sustainable Development to assess several photovoltaic facilities in the area covered by the institute. Concluding the paper, some operational results of the revitalized system are presented. Copyright © 2011 John Wiley & Sons, Ltd.     

Bandwidth allocation and distributed relay selection for multiple‐user and multiple‐relay cooperative systems using Stackelberg game

Cooperative communication is an ongoing research area which lies on the basic idea of transmission of information from the transmitter to the receiver with the assistance of a virtual array of relay nodes in between, which will eventually provide the spatial diversity. This paper deals with the resource allocation (bandwidth in this case) among multiple users (source‐ destination pairs) in a cooperative communication environment along with the relay selection when there are multiple relay nodes to assist the transmitting nodes to pass on their data signal to respective receivers. A multi‐user, multi‐relay system model is considered here on which Amplify‐and‐Forward relaying scheme is applied. The bandwidth allocation and relay selection are done based on the Stackelberg game according to which transmitting nodes are treated as purchasers and relaying nodes are treated as vendors. By this planned approach, the transmitting nodes can discover the relays at comparatively better positions and can purchase the optimal bandwidth from those helping relays. By this approach, the relays which are competing with each other can increase their own utilities by demanding the optimal prices and the multiple users which are competing with each other can maximize their own utilities by demanding the optimal bandwidths. Distributed relay selection scheme is applied here which does not require precise information of channel state information as opposed to Centralized scheme and it gives comparable results, too.     

Adaptive modulation and coding for Long Term Evolution‐based mobile satellite communication system

The adaptive modulation and coding (AMC) scheme is mandatory for modern wireless communication systems to overcome inevitable channel impairments. Many of the limitations using AMC are due to the long round‐trip delay of a satellite system. This paper proposes an efficient AMC scheme with power control and symbol interleaving that can be effectively applied to satellite systems. In particular, we focus on mobile satellite systems that have maximum compatibility in a Long Term Evolution system. Simulations reveal that the proposed scheme can provide a maximum 10.2% increase of average beam spectral efficiency and a maximum of 8‐dB power gain compared with a conventional AMC scheme. Copyright © 2012 John Wiley & Sons, Ltd.     

Simulations and experiments for optimal deployment of an RFID‐based location‐aware system

The proliferation of communication and mobile computing devices and local‐area wireless networks has cultivated a growing interest in location‐aware systems and services. An essential problem in location‐aware computing is the determination of physical locations. RFID technologies are gaining much attention, as they are attractive solutions to indoor localization in many healthcare applications. In this paper, we propose a new indoor localization methodology that aims to deploying RFID technologies in achieving accurate location‐aware undertakings with real‐time computation. The proposed algorithm introduces means to improve the accuracy of the received RF signals. Optimal settings for the parameters in terms of reader and reference tag properties were investigated through simulations and experiments. The experimental results indicate that our indoor localization methodology is promising in applications that require fast installation, low cost and high accuracy. Copyright © 2009 John Wiley & Sons, Ltd.     

Telesurgery QoS improvement over SDN based on a Type‐2 fuzzy system and enhanced cuckoo optimization algorithm

Telemedicine is a new area based on the information and communication technology for collecting, storing, organizing, retrieving and exchanging medical information. One of the most important applications of telemedicine is indeed telesurgery in which an efficient telecommunication infrastructure between the surgery room and remote surgeons need to be established. One of the most important issues to be tackled in telesurgery is to find favorable links for routing as well as providing high Quality of Service (QoS). In this paper, an efficient model based on the hybridization of Type‐2 Fuzzy System (T2FS) and Cuckoo Optimization Algorithm (COA) over the Software Defined Networks (SDN) is proposed in order to achieve optimal and reliable routes for telesurgery application. Using T2FS, the fitness of the links is determined; then, a COA is conducted over the Constraint Shortest Path (CSP) problem to find the best routes. Delay is considered as a CSP problem which is satisfied by trying to find the paths with minimum cost. Due to the NP‐completeness of the CSP problem, an Enhanced COA (so‐called E‐COA) is proposed and utilized as a metaheuristic solver. To the best of our knowledge, this paper is the first SDN‐based communication model that applies both T2FS and E‐COA for assigning proper costs to the network's links, and solves the consequence CSP problem according to the QoS requirement for telesurgery. The model also recognizes and preserves the second‐best routes in order to keep the reliability for such a critical application. In addition to the simulations, the performance evaluation is also conducted on a real experimental scenario. Many comparisons are carried out between the proposed model and other conventional methods, and the evaluation study shows the superiority of the proposed model on all the three QoS‐related metrics, i.e. average end‐to‐end delay, packet loss ratio and PSNR.     

Expectation–maximization‐based joint data detection and channel estimation for a cellular multi‐carrier code division multiple access network using single‐hop relaying

This paper is concerned with channel estimation and data detection for a cellular multi‐carrier code division multiple access network using single‐hop relaying in the presence of frequency selective fading channels. The proposed expectation–maximization (EM) algorithm was used to jointly estimate both the coefficients of the channel between a relay and a base station and the data. EM algorithm is particularly suited to multi‐carrier code division multiple access systems because they have multi‐carrier signal format. The considered network uses single‐hop relaying technique to provide a higher quality transmission to the users with low quality channels. The base station (managing mechanism) gives them an opportunity to send their messages via the users with high quality channels in a time sharing mode. The performance of the proposed EM algorithm, with and without hopping and with cooperative communication technique, was analyzed by a computer simulation, and the results are presented. Copyright © 2011 John Wiley & Sons, Ltd.     

Value‐centric framework and pareto optimality for design and acquisition of communication satellites

Investments in space systems are substantial, indivisible, and irreversible, characteristics of high‐risk investments. Traditional approaches to system design, acquisition, and risk mitigation are derived from a cost‐centric mindset, and as such they incorporate little information about the value of the spacecraft to its stakeholders. These traditional approaches are appropriate in stable environments. However, the current technical and economic conditions are distinctly uncertain and rapidly changing. Consequently, these traditional approaches have to be revisited and adapted to the current context. We propose that in uncertain environments, decision‐making with respect to design and acquisition choices should be value‐based. We develop a value‐centric framework, analytical tools, and an illustrative numerical example for communication satellites. Our two proposed metrics for decision‐making are the system's expected value and value uncertainty. Expected value is calculated as the expected NPV of the satellite. The cash inflow is calculated as a function of the satellite loading, its transponder pricing, and market demand. The cash outflows are the various costs for owning and operating the satellite. Value uncertainty emerges due to uncertainties in the various cash flow streams, in particular because of market conditions. We propagate market uncertainty through Monte Carlo simulation, and translate it into value uncertainty for the satellite. The end result is a portfolio of Pareto‐optimal satellite design alternatives. By using value and value uncertainty as decision metrics in the down‐selection process, decision‐makers draw on more information about the system in its environment, and in making value‐based design and acquisition choices, they ultimately make more informed and better choices. Copyright © 2009 John Wiley & Sons, Ltd.     

Development of monitoring system for FTTH‐PON using combined ACS and SANTAD

This paper proposes a design of Access Control System (ACS) for fiber‐to‐the‐home passive optical network (FTTH‐PON). Our design works on a standard local area network using a specially designed hardware interfaced with a microcontroller integrated Ethernet to monitor the status of optical signals flow and provides the restoration against fiber failures/faults in FTTH‐PON. We also introduce the centralized troubleshooting system by means of Smart Access Network Testing, Analyzing, and Database (SANTAD). ACS is the subsystem that controls the troubleshooting mechanism carried out by SANTAD. This design will be implemented together with optical line terminal (OLT) at central office (CO) to centralized monitoring and for controlling each optical fiber line's status as well as detecting any failure that occurs in the network system downwardly from CO toward multiple optical network units at different customer residential locations. The scope of this discussion highlighted only the monitoring and controlling instead of the restoration scheme offered. Copyright © 2009 John Wiley & Sons, Ltd.