通信专业英语作文【篇一：通信工程专业外语介绍二极管作文】? 1、there are two types of standard transistors,npn and pnp,with different circuit symbols. the letters refer to the layers of semiconductor material used to make the transistor.2、the leads are labelled base(b),collector(c)and emitter(e).these terms refer to the internal operation of a transistor.3、transistors amplify currents,for example they can be used to amplify the small output current from a logic chip so that it can operate a lamp,relay or other high current device.in many circuits a resistor is used to convert the changing current to a changing voltage,so the transistor is being used to amplify voltage.4、a transistor may be used as a switch (either fully on with maximum current,or fully off with no current)and as an amplifier(always partly on).【篇二：通信工程-专业英语论文】《专业英语》课程论文论文题目：wireless sensor network node 学院(系)：信息工程学院专业：电子科学与技术班级：学生姓名：胡剑学号：1049721303194 教师：徐文君2014年 5月 16 日wireless sensor network node positioningalgorithmhu jianschool of information engineering,wuhan university of technology, wuhan, chinaabstract- wireless sensor networks as a new type of data node localization algorithm to complete. targeting the acquisition technology, combined with microelectronics, location of the network nodes is known as the reference wireless communications and wireless networks, such as node, the destination node determines that the event or multi-discipline, have broad application prospects in the field of the location in the network.industrialcontrol,military,medicalassistance,andenvironmental monitoring. in most applications, the physical location of the guide to the sensor node is a basic requirement, however, due to the large number of sensor nodes, randomly distributed, and the software and hardware resources are limited, so study effective positioning algorithm to determine the location of each node has an important theoretical significance and practical value.access to large amounts of literature on the basis of the lessons do an overview of the wireless sensor network-based positioning technology, wireless sensor networks, highlights several typical distributed positioning algorithm principle and characteristics, including amorphous , apit, centroid, dv-hop, rssi, etc., its matlab simulation environment simulation analysis, and compare the positioning accuracy of the various algorithms and error.keywords: wireless sensor algorithm, matlab, simulation analysisnetworks, localizationii. system designtin sensor networks, most existing node localizationalgorithms, reference anchor nodes are positioned to take advantage of the way place. a large number of sensor nodes in the target area in the layout: a portion called the particular node, also called anchor node (beacon), which themselves can be obtained by carrying the exact location of the gps positioning apparatus or artificial means, and have more than node powerful capabilities, but such a small proportion of nodes; node other unknown locations themselves, through their neighbor nodes to communicate to get information of each anchor nodes, these nodes using the locationinformation as a reference, and use some calculations to get their position known to the unknown is called a node (node)in wireless sensor networks usually used only two-dimensional coordinate system of .so long as we know from the unknown node with three anchor nodescan calculate the position of the unknown node.i. introductionpositioning of wireless sensor networks is the wireless, self-organizing network to provide location information of nodes in the network in some way, self-organizing network localization process can be divided into self-positioning and targeting node node positioning itself to determine the coordinates of the information network node . the targeting information is needed to determine the coordinates of a target within the network coverage or an event. node itself is the process of determining the positioning properties of the network itself, or you can use the manual calibration of variousfigure 1. schematic trilateral positioningassuming three anchor node coordinates are (x1,y1), (x2, y2), (x3, y3), the coordinates of the unknown node (xu, yu), unknown node distances from three anchor nodes are r1, r2 , r3, shown in figure 3-2, the distance formula based on a two-dimensional coordinate system of equations can be obtained asfollows:(1)the above equations are usually solved using the maximum likelihood method estimates the unknown node coordinate multilateral used (xu, yu)：(2)in summary, it may obtain a plurality of unknown nodes as long as the anchor node that the unknown distance from the node to the anchor node 3 may be positioned on the practical application of the unknown node, this calculation can be different for each selected three points, and finally the results were averaged for several times and thus improve the positioning accuracy.iii. specific positioning algorithma. apit algorithmapit algorithm theoretical basis is the best point inside the triangle test method pit. pit test principle is that if there is a direction unknown nodes simultaneously moving along this direction away from or close to three beacon nodes, then the unknown nodes located in three beacon nodes outside the triangle; otherwise unknown nodes located within the triangle. point test using the network in a relatively high density ofnodes to simulate the mobile nodes using wireless signal propagation characteristics to determine whether far or near beacon nodes within the approximate triangle, usually in a given direction, a node from another node the farther the received signal strength is weaker. neighbor nodes exchange their received signal strength determination of a distance of beacon nodes, the nodes to move mimic pit. b.centroid positioning algorithmcentroid algorithm, the beacon node to a neighboringnode periodically broadcasts a beacon packet, a beacon packet contains the identification number and the location information of beacon nodes. when the node receives the unknown number of different beacon beacon packet from a node or reception exceeds a certain threshold time, the position of which determines its beacon nodes consisting of the centroid of the polygon.centroid algorithm based solely on network connectivity, and therefore relatively easy to implement. however, this method is affected by the density of the beacon nodes. centroid algorithm for improved algorithm, density adaptive heap algorithm, by increasing the beacon beacon nodes nodes in a low density area in order to improve the positioning accuracy.c. dv-hop positioning algorithman advantage of the proposed method of ideological distance vector routing and gps positioning. consists of three phases: first, all nodes in the network to obtain the number of hops from a beacon node; secondly, when obtaining the position and the other beacon nodes hop distance apart, the beacon nodes calculate the average hop distance of the network, giving their survival period, then the survival of the school with a positive value in the webcast. unknown node receives only record the first correction, and forwarded to the neighbors.this strategy ensures that the vast majority of node receives an average hop distance from the nearest beacon node. according unknown node hops records to calculate distance to jump beacon nodes.... d. rssi algorithmrssi measurement model and the theoretical model of general experience using the signal propagation. for empirical model before the actual positioning, first select a number of test points, records the received signal strength at these points ofthe base stations, to establish the relationship between position and signal strength line database (x, y, ss1, ss2 respective points, ss3 ). in the actual positioning, based on the measured signal strength (ss1 , ss2, ss3 ) and the signal strength recorded in the database by comparing the variance of the coordinates of the minimum signal strength that are used as the coordinates of the node point.iv. the simulation resultsa.apit algorithmfigure 4. figure positioning error（red * indicates anchor nodes, blue o represents an estimate offigure 2. node distribution（300 nodes, including 60 anchor nodes, red * indicates anchornodes, blue o represents the unknown node）the position of the unknown node, black o that they can not be positioned unknown nodes, blue - shows the positioning error of unknown nodes (nodes connected to an unknown location and estimate the true position), a total of 300 node: 60 anchor nodes, 240 unknown nodes, 0 unknown nodes can not be located, the positioning error of 0.29857）v. conclusionsfive algorithms are square_random selected node distribution, gps errors are 30m, communication radius comm-r are 200 unified communication model for the same communication model regular model folder, a list of error will be calculated by the five algorithms，as shown in figure 5:figure 3. neighbor relationship diagram（300 nodes, including 60 anchor nodes, red * indicates anchornodes, red o indicates unknown node communication radius: 200m, anchor node communication radius:200m, communication model: regular model, the average connectivity of the network is: 31.1133, the average number of neighbor nodes of the network anchor is: 6.18）figure 5. positioning deviationseen from the table, the maximum error and the centroid apit algorithm followed dv-hop algorithm then amorphous algorithm is the smallest error rssi algorithm.references[1] ou dexiang, wang zhizhong. “the design for intelligent node o f dcs based can bus”. electronic computer design world, vol 19,2002.[2] sun huixian, zhang yuhua, luo feilu. “data collection system for power monitor based on usb and can bus”. proceedings of the csu–epsa, vol 21, pp: 99-103, 2009.[3] zhang zhen-wei, huang shi-hong, “the design of vibration signal acquisition system,” turbine technology, 49 (3), pp.187-188, march 2007.[4] xu huazhong, “feng bo. design of usb module based on pdiusbd12.”.journal of wuhan university oftechnology(informationmanagement engineering), vol 02, 2008.[5] li jinbo. “design and realization of usb2．0 interface in equipment condition monitoring instrument”. process automation instrumentation. vol 29, pp: 14-17, 2008.【篇三：通信英语专业论文】the development trend of modernmobile communicationabstractrecalling the development history of the mobile communication,development of mobile communications has gone through several stages of development.the first generation of mobile communication technology mainly refers analog cellular mobile communication ,technical characteristics of a cellular network architecture to overcome the large district system capacity is low, the problem of limited range of activities.the second generation mobile communications is a cellular digital mobile communication, the cellular system can be provided with digital transmission and various advantages of integrated services.the third generation mobile communications also known as modern mobile communications.it is in addition to the main features of a second-generation mobile communication systems have various advantages and overcome its shortcomings, but also able to provide broadband multimedia services, can providehigh-quality video broadband multimedia integrated services, and to achieve global roaming.third generation technology is not too successful today,but it has great prospects for development.so lets talk about development trend of modern mobile communication.in the information technology support, market competition and demand together, the development of mobile communication technology is leaps and bounds, showing the following major trends:network traffic data, packet; broadband network technologies; intelligent network technology; higher frequency bands; more effective use of frequencies; various networks to converge. understand and master these trends on mobile operators and equipment manufacturers have important practical significance.work traffic data, packetmobile wireless data communications are considered the main direction of development. in recent years there are mainly two kinds of mobile data communications, one is circuit-switched mobile data services, the other is packet-switched mobile data industry.wireless data services is the main driving force of the users application , and other areas of communication, wireless data services one of the most important driving force from the internet.quest for voice communication anytime, anywhere mobile communications success so early. mobile communications business value and user market has been proved that the global mobile market with extraordinary pace. the next phase of the evolution of mobile communications is to provide mobile multimedia wireless data transfer and even individuals, this progress has already begun, andwill be an important future growth. personal mobile multimedia will provide people based on location can not imagine, perfect service and wireless personal information will people work and all aspects of life impact.2.broadband network technologiesin the history of the telecommunications industry, mobile communications technology and the market may be the fastest growing areas. business, technology and market interaction among a relationship, along with the user data and multimedia services demand increases, the data network service, packetdevelopment of broadband mobile networks will inevitably move toward.the third-generation mobile systems, namely imt-2000, is a true broadband multimedia system that can provide high-quality broadband integrated services and achieve seamless global coverage. after 2000, the narrow-band mobile phone business needs will remain large, but with the internet and other high-speed data communications and multimedia communications demand-driven, integrated broadband multimedia services will gradually increase, and the construction of the future information superhighway seamless coverage in terms of , broadband mobile communications as a whole, a subset of the mobile market share will become increasingly important.3.intelligent network technologygrowing demand for mobile communications and new technologies in mobile communication widely used, prompting the mobile network has been developing rapidly. mobile network consists simply transfer and exchange of information, and gradually to store and process information, the development of intelligent, mobile intelligent network as a result.along with the mobile network evolution to third generation systems, intelligent networks are constantly improved. intelligent network and its intelligence services constitute the basic conditions for future personal communications.4.higher frequency bandsfrom the first generation analog mobile phone, to the second generation of digital mobile networks, to the future of the third generation mobile communication systems, networks using wireless spectrum from low to high to follow a trend. born in 1981, the first international roaming nmt analog systems use frequency band 450mhz, 1986 年 nmt changes to the 900mhz band. chinas current band analog tacs system is used for 900 mhz. in the second generation networks, gsm systems use frequency band is started 900mhz, is-95 cdma system is800mhz. in order to from the fundamentally improve the gsm system the capacity of the,1997 appeared in 1800mhz system, gsm 900/1800 dual-band network rapid popularization. 2002 will be put into commercialthird generation systems imt-2000 is positioned in the 2ghz band.5.more effective use of frequenciesradio frequency is a valuable resource. with the rapid development of mobile communications, spectrum resources are limited and the dramatic increase in mobile subscribers increasingly acute contradictions, a frequency of severe shortage phenomenon. frequency congestion problem solving way is to use various frequency effective use of technology and development of new bands.as the future mainstream of the third generation mobile communication systems wireless access technology wcdma (wideband code division multiple access) to more efficient use of radio frequencies. it uses hierarchical cell structure, adaptive antenna array and coherent demodulation (bidirectional) technology, a substantial increase in network capacity available that can better meet the requirements of the development of future mobile communication.6.various networks to convergetechnological developments, changes in market demand, market competition and market control policies will relax computer。
