Subject Area Broadband consumerhome access to the internet. Correspondence Address
通信专业英语之G网络
Translation oห้องสมุดไป่ตู้ Text 6
行业的发展带来了大量的4G兼容设备。目 前已有数十种不同的移动设备，而且不局限于 4G手机或笔记本电脑，如摄录像机、游戏装置 、自动售货机和冰箱等。
Translation of Text 7
The trend is to provide wireless internet access to every portable device that could supply and incorporate the 4G embedded modules. The 4G technology could not only provide internet broadband connectivity but also a high level of security that is beneficial to devices that incorporate financial transactions such as vending machines and billing devices.
Translation of Text 5 0
1
目标
由ITU为WiMAX和LTE设定的目标是：当用 户高速相对于基站移动时，数据速率达到 100Mbps；位置固定时，达到lGbps。
Translation of Text 6
The industry moves towards expansion of the number of 4G compatible devices. It is set to find its way to tens of different mobile devices not restricted to 4G phones or laptops, such as Video Camera, Gaming Devices, Vending Machines, and Refrigerators.
(学案)必修1Module6 TheInternetandTelecommunications含解析
[主题词块背诵]1．big data 大数据2．data processing 数据处理3．surf the Internet 网上冲浪4．cyber space 网络空间5．smart keyboard 智能键盘6．cell phone addicts 手机迷7．leak personal information 泄漏个人信息8．a sense of security 安全感9．face scanning 面部识别10．artificial intelligence 人工智能11．electronic devices 电子设备12．face recognition technology 人脸识别技术[主题佳句背诵]1．There is no doubt that the Internet has made it easier for us to keep up with the latest information.毫无疑问，互联网使我们更容易了解最新的信息。
2．There is no denying that cell phones have brought us considerable convenience.不可否认，手机给我们带来了巨大的便利。
3．Although computers have many advantages，they can not carry out creative work and replace man.尽管计算机有许多优点，但是它们不能进行创造性的工作，也不能代替人。
NO.1单词－－在语境中默写，在联想中积累[先识记]1．concentrate v i.集中(注意力、思想等)2．shorten v t.缩短3．contain v t.包含；包括4．create v t.创造；发明5．design v t.设计6．crash v i.(计算机)崩溃7．log v t.记录；登录8．pass v t.超过9．accessible adj.可进入的；可使用的10．frequently ad v.时常；经常11．independent adj.独立的12．average adj.平均的13．fantastic adj.极好的；美妙的14．military adj.军事的；军队的15．sideways ad v.横着地；斜着地16．source n．来源；出处17．defence n．保护；防卫18．percentage n．百分数；百分率19．document n．文件20．invention n．发明21．permission n．许可22．disadvantage n．弊端；缺点23．software n．软件24．data n．(复)数据25．access n．接近；通路[再运用]用所给词的适当形式填空1．Concentration is important for this kind of work，and only by concentrating on it can you get it done well.(concentrate)2．It's believed that hard work can create wealth but the creation of wealth also needs creative quality.(create)3．The famous building is said to be designed by an outstanding designer called Jason.(design) 4．Fallen rocks cut off the only access to the village，so it is not accessible to the outside now.(access)5．You should learn to be independent(depend) of your parents.6．Mr Smith，an inventor，has invented many useful things and has made much money from his inventions．(invent)7．His father wouldn't permit him to drive there even if he had got his driving permit.Without his father's permission，he had no choice but to go there by bus or on a bike.(permission)[英英释义]1．definite adj. A．a short piece of writing/article/passage on a particular subject2．essay n. B．password；a secret number or phrase3．keyword n. C．having clear limits；clear or certain4．network n. D．a sudden failure in operation；mistake；fault 5．statistics n. E．a large system of lines that are connected with one another6．breakdown n. F．numerical statement；numbers collected for a special purpose答案：1.C 2.A 3.B 4.E 5.F 6.D[联想记忆]1．“独立”和“依赖”相关词集锦①depend v．依赖②dependent adj.依赖的③dependence n．依赖④independent adj.独立的⑤independence n．独立2．“v.＋prep./adv.”合成名词万花筒①breakup破裂②breakthrough突破③makeup化妆品④gettogether聚会⑤setback挫折⑥breakdown故障3．后缀“-sion”名词大观园①permission允许②decision决定③discussion讨论④possession拥有⑤explosion爆炸NO.2短语－－在应用中记牢，在归纳中记多[先识记]1．log on/off注册/注销2．consist of由……组成3．as well也4．become known as...作为……而出名；被称为……；叫作……5．go down下降6．come up with提出7．from that moment on从那时起8．concentrate on聚精会神；集中思想9．compared with与……相比10．a series of一系列的11．come across偶然遇到12．when it comes to当提到……[再运用]选用左栏短语填空1．It is said that success consists of three important factors：talent，diligence and luck.2．We are going to the cinema tonight.Why don't you come along as well?3．Compared with the place where I grew up，this town is much more exciting.4．From that moment on，I began to do some writing using an old computer offered by my friend. 5．There is a series of science and technology on the desk.[联想记忆]1．由log on/off想到的①turn on/off打开/关闭②switch on/off打开/关闭③get on/off上车/下车2．“由……组成”短语多棱镜①consist of由……组成②be made up of由……组成③be composed of由……组成3．known相关短语全扫描①be known as作为……而出名②be known to sb.为某人所熟知③be known for因……而出名NO.3句式－－在解读中学懂，在仿写中学通►句型1[原句展示]It then became possible for universities to use the system as well.[句型提炼]It＋be/becomes (became)＋adj.＋(for sb.)to do sth.[仿写应用](2019·高考全国卷Ⅰ)很难计算出北极熊的全球数量，因为(它们活动的)范围的大部分都没有得到很好地研究。
管理沟通以案例分析为视角英文版第5版教辅文件IM 5e Chapt 07
T ECHNOLOGYC HAPTER 7“Technology is a two-edged sword with the potential to make us more productive,or to drain away our time.”I. Life in the Digital AgeA. It’s quicker, cheaper and easier to ship electrons (as in e-mail attachments) than it isto ship atoms and molecules (as in FedEx overnight packages).B. The way we work and live has changed. We can find anyone with a cell phone orpersonal computer in a matter of seconds.C. Since the advent of PC’s just over 25 years ag o, more than a billion have soldworldwide.D. By 2011, more than 80 percent of all U.S. households had access to at least onepersonal computer, and 66 percent had in-home access to broadband connections.II. Communicating DigitallyA. The means of production are now in our minds, in our hands, and on our desktops.B. For all of the advantages which this new technology brings to our homes, ourbusinesses, and our lives, there are complications.1. There is no longer a distinction between work and home.2. In the U.S., more than $650 billion a year in productivity is lost due tointerruptions and inattention.3. Managers rely on fewer nonverbal and visual cues to gather meaning due toworking across time zones and with geographically dispersed groups andteams.III. Managing Electronic MailA. If you have a problem, admit it. White collar workers waste an average of threehours a week sorting through junk mail. If you spend more time than that,you have a problem.B. Send less. Get less. If you send less e-mail you’ll reduce the volume of return mailin your inbox.C. Escape the endless reply loop. Finish a message with “No reply needed,” or follow arequest with “Thanks in advance.”D. Check the “To” field before you click “Send.”E. Don’t copy the world. Think twice about the people you put on your “cc” list.F. Pick a subject, (almost) any subject. Crafting a relevant subject line will promptpeople to open your messages and act on them quickly.G. Think before replying. If you respond to e-mail messages immediately, youestablish the expectation in your readers’ minds that you will always respond quickly.H. Think again before replying. If you’re angry, upset, or irritated at something you’vejust read in an e-mail message, give yourself a day – or at least a few hours – to cooldown before responding. You may end up saying something you’ll regret.I. Be careful with criticism. E-mail eliminates virtually all of the important nonverbalcues we’re accustomed to seeing and hearing as we judge a message sender’s intent.J. Handle each message just once. If it’s unimportant or irrelevant, hit the delete key.File each message you want to keep in a folder as it comes in.K. Don’t check your e-mail constantly.L. Don’t ignore the conventions of c orrespondence. You should not write to people in all lower case letters, ignore punctuation, or abandon conventional spelling.M. Avoid abbreviations and cyberjargon. You can’t assume everyone is familiar with the endless acronyms circulating out there.N. Try to keep messages under two or three paragraphs.O. Make URLs Useful.P. Be cautious about attachments. Don’t attach documents, pictures, or spreadsheets to your messages unless you’re certain the recipient wants or needs to see them.Q. Include a signature file.R. Check your time/date stamp.S. Get help when you need it.IV. Privacy and Workplace MonitoringA. Why Do Employers Monitor?1. Security. Every business has information that it wants kept confidential.2. Productivity. More than one-third of all lost productivity is attributed toInternet abuse at work.3. Protection. Many companies faced with costly lawsuits are monitoring e-mail,voice mail, and other communication systems to uncover and disciplineworkers who harass or intimidate others in the workplace.4. Industry Regulation. State and federal regulatory agencies have publishednumerous rules requiring businesses of many sorts to hang onto all of their e-mail, just as they would retain their paper-based correspondence.B. Does an Employee Have a Right to Privacy?1. No federal law covers all aspects of an employee’s right to privacy on the job.Instead, a patchwork of federal and state laws regulates everything fromelectronic monitoring to visual surveillance, drug testing and locker searches.2. Employees really do not have a right of privacy in e-mailcommunication on their employer’s system, unless theemployer acts in a manner giving rise to a reasonableexpectation of privacy.3. The Electronic Communication Privacy Act of 1986, asamended, protects e-mail messages from interception by anddisclosure to third parties.C. Employer Rights. An employer has the right:1. To intercept and review e-mail messages generated,transmitted, stored, or received on a company-owned or leasedsystem;2. To conduct an e-mail audit to determine how the system isbeing used, when, and under what conditions, for whatpurposes, and by whom;3. To disclose certain e-mail content to third parties if anappropriate authority (postmaster or system administrator)suspects or discovers illegal or unauthorized use;4. To require employee training in e-mail system use;5. To receive employee acknowledgment of training andunderstanding of e-mail system policy guidelines, restrictions,and limitations.D. Employer Expectations. An employer may reasonably expect:1. That company-owned e-mail systems will be used principallyor exclusively for official business purposes;2. That employees will not use company-owned e-mail systemsfor profit, private gain, or personally owned businesses;3. That employees will not use company-owned systems forillegal purposes;4. That employees will not use company-owned systems forunauthorized disclosure of proprietary data or confidentialinformation;5. That employees will not use company-owned systems to sendinappropriate messages, including rude or discourteousmessages, sexually harassing messages, sexist or racistlanguage, profane language, obscene language or graphicimages or correspond with unauthorized addresses.E. Can my Employer Listen to My Phone Calls at Work?1. Employers may monitor calls with clients or customers for training purposesto assure quality control.1. Federal law, which regulates phone calls with people outside the state doesnot allow unannounced monitoring for business-related calls.2. Under Federal law, when an employer realizes a call is personal, he or shemust immediately stop monitoring the call.F. Can my Employer Obtain a Record of My Phone Calls?1. Telephone numbers dialed from phone extensions can be recorded by penregisters. It allows an employer to see a list of phone numbers dialed by yourextension and the length of each call.2. A new programming concept called “presence awareness” is able todetermine whether a PC, cell phone or wireless device is turned on or in use.G. Can my Employer Watch my Computer Terminal While I Work?1. Since your employer owns the computer network andterminals, he or she is free to use them to monitor employees.2. Union contr acts may limit an employer’s right to monitor.H. What Sort of Things Can They Monitor?1. Very inexpensive software and easy-to-operate hardwaremake it possiblefor almost any employer to know who has company-providedInternet access, who’s online, what they’re watching, howoften, and for how long.2. New software will now permit an employer to follow what’shappening on each employee’s computer screen.I. How Can I Tell If I am Being Monitored?1. Most computer monitoring equipment allows employees tomonitor without an employee’s knowledge.2. Some employers notify their workers that monitoring takesplace. If you know they’re watching, you’re more likely tobehave yourself.J. Is My Voice Mail Private?1. Voice Mail and e-mail are regarded as being nearly the samein the eyes of the law.2. The telephones, switching equipment, and the computer harddrives on which the voice mail is stored are the property of thecompany, and the company can access, store, and listen toanyone’s voice mail.K. Is There Any Way I Can Keep My E-mail and other Work Private?1. Yes, but an employer may forbid it.2. You could encrypt a personal e-mail message before you send it.L. Can Instant Messages be Monitored?1. An employer can monitor just about anything including AOL InstantMessenger.2. Many corporations have brought instant messaging into theoffice to make small groups and teams more effective.V. The Internet and Online BehaviorA. A survey of college students across the country found that 94 percent use the Internet,compared with just 66 percent of the overall U.S. population.B. Other findings about college students’ online use revealed the following.1. To them, the Internet and e-mail are as commonplace as telephones andtelevisions, and equally as indispensable.2. Two-thirds of them say they think the Internet has improved theirrelationships with classmates, and more than half think e-mail has enhancedtheir relationships with professors.3. These habits are clearly likely to continue once students enter the workforce.C. The Internet has become central to the way college students conduct research fortheir courses; communicate with their professors, friends, and family, and gatherinformation about everything from sports to the stock market and the weather.VI. Text MessagingA. Behind the texting explosion is a fundamental shift in how we view our mobile devices.1. Average “talk minutes” are down, but text messaging is up for both teenagers andadults.2. Text messaging takes up less bandwidth than phone calls, and costs less.3. Part of what’s driving the texting surge is the popularity of social media sites likeTwitter or Facebook.4.The goal is to pass along information in as little time, with as little small talk aspossible. Textin g’s rise over conversation is changing the way we interact.VII. Social MediaA. Social media is a term widely used to include many Internet-based functions and severalimportant categories are worth noting.1. Social bookmarking are sites that interact by tagging Web sites and searching onesbookmarked by other people.2. Social news sites interact by voting for articles (most popular, most read, most e-mailing)and commenting on them.3. Social networking sites like Facebook and MySpace interact by adding friends,commenting on profiles, joint groups and holding discussions.4.Social photo and video sharing sites like YouTube and Flickr interact by sharing photos orvideos.5.Wikis, such as Wikipedia and Wikia interact by adding articles and allowing users to editexisting articles online.B. Businesses are beginning to figure out how to use social media, primarily for marketingpurposes, but also for reputation management and corporate communication.C. On your own time, social media can be helpful for boosting your career and connecting withfriends.1. Just be careful how much you log on at work.2. It’s best to log on from a private computer or smart phone and to do it during break times.3. Keep in mind that there is still a risk. Don’t trash your boss or co workers or complain tooseverely about work.VIII. Etiquette and Office ElectronicsA. Cell phones1. Turn them off while driving.2. Turn them off while in any location where people expect some measure ofprivacy and quiet.3. Don’t assume those around you are interested in hearing your conversation.4. Don’t assume that because your employees own a cell phone that they areavailable to talk business 24 hours a day, 7 days a week.B. Voice Mail1. Keep your outgoing message brief.2. One outgoing message is fine unless you plan to be gone for a week.3. Tell people how to get past the outgoing message.4. When leaving a voice mail message, identify yourself, give your call back number,and explain briefly why you’re calling.5. Don’t listen to your voice ma il messages on the speaker phone.C. E-Mail1. Don’t send e-mails that make angry demands.2. Don’t waste recipients time with the latest “jokes du jour.”3. Don’t order people to visit your web page.4. Don’t write to anyone in all lower case letters or s hout at your readers in all capital letters.5. Don’t ever insult, malign, harass or demean your readers or anyone else in those e-mailmessages you write.6.Include a salutation, complimentary close and – in the first paragraph or two – a statementof purpose.VII. Working VirtuallyA. Advantages1. Cost – paying less for office space and employee support;2. Productivity – reduced absenteeism and increased employee retention;3. Access – to its own employees at unusual times and places;B. Disadvantages1. Costs – initial outlay to purchase equipment can be significant;1. Technology – concerns about providing technical support to remote workers;2. Culture – telecommuters may not be given the same opportunities fortraining, advancement, or promotion;3. People – many take pride in their office, enjoy socializing andinteracting with their co-workers and colleagues and find the climatein their work locations energizing and inspiring;VIII. TeleconferencingA. Planning a Teleconference1. Identify the purpose of your teleconferencing meeting.2. Identify the person who will chair the meeting.3. Plan the agenda.4. Distribute the agenda.5. Schedule the teleconference.6. Confirm the teleconference with the participants.7. Share important resource materials with participants.B. Conducting a Teleconference1. Get to the conference site early.2. Watch what you wear.3. Act as if people are watching you.4. Start on time.5. Take control of the conference.6. Ask participants to introduce themselves as you begin.7. Jot down peop le’s names and locations.8. Ask participants to identify themselves when they speak for the first time.9. Speak a bit more slowly to ensure that everyone can understand you.10. Avoid side conversations.11. Be patient if the system includes a slight delay.12. Try to make eye contact with the camera.13. Don’t read a speech or prepared statement.14. Summarize key issues as you move along.15. Establish what’s next for the group.16. Stop on time.17. Prepare and distribute minutes of the teleconference.。
计算机网络英文题库(附答案)chapter
Chapter 1 Computer Networks and the Internet1．The ( ) is a worldwide computer network, that is, a network that interconnects millions of computing devices throughout the world. ppt3A public InternetB IntranetC switch netD television net2．Which kind of media is not a guided media? ( )A twisted-pair copper wireB a coaxial cableC fiber opticsD digital satellite channel3．Which kind of media is a guided media? ( )A geostationary satelliteB low-altitude satelliteC fiber opticsD wireless LAN4．The units of data exchanged by a link-layer protocol are called ( ).A FramesB SegmentsC DatagramsD bit streams5．Which of the following option belongs to the circuit-switched networks? ( )A FDMB TDMC VC networksD both A and B6．( )makes sure that neither side of a connection overwhelms the other side by sending too many packets too fast.A Reliable data transferB Flow controlC Congestion controlD Handshaking procedure7．( ) means that the switch must receive the entire packet before it can begin to transmit the first bit of the packet onto the outbound link.A Store-and-forward transmissionB FDMC End-to-end connectionD TDM8．Datagram networks and virtual-circuit networks differ in that ( ).A datagram networks are circuit-switchednetworks, and virtual-circuit networks arepacket-switched networks.B datagram networks are packet-switchednetworks, and virtual-circuit networks arecircuit-switched networks.C datagram networks use destinationaddresses and virtual-circuit networks useVC. numbers to forward packets toward theirdestination.D datagram networks use VC. numbers andvirtual-circuit networks use destinationaddresses to forward packets toward theirdestination.9．In the following options, which one is not a guided media? ( )A twisted-pair wireB fiber opticsC coaxial cableD satellite10．Processing delay does not include the time to ( ).A examine the packet’s headerB wait to transmit the packet onto the linkC determine where to direct the packetD check bit-error in the packet11．In the following four descriptions, which one is correct? ( )A The traffic intensity must be greater than1.B The fraction of lost packets increases asthe traffic intensity decreases.C If the traffic intensity is close to zero,the average queuing delay will be close tozero.D If the traffic intensity is close to one,the average queuing delay will be close toone.12．The Internet’s network layer is responsible for moving network-layer packets known as ( ) from one host to another.A frameB datagramC segmentD message13．The protocols of various layers are called ( ).A the protocol stackB TCP/IPC ISPD network protocol14．There are two classes of packet-switched networks: ( ) networks and virtual-circuit networks.A datagramB circuit-switchedC televisionD telephone15．Access networks can be loosely classified into three categories: residential access, company access and ( ) access.A cabledB wirelessC campusD city areaQuestion 16～17Suppose, a is the average rate at which packets arrive at the queue, R is the transmission rate, and all packets consist of L bits, then the traffic intensity is ( 16 ), and it should no greater than ( 17 ).16． A LR／aB La／RC Ra／LD LR／a17．A 2B 1C 0D -118．In the Internet, the equivalent concept to end systems is ( ).A hostsB serversC clientsD routers19．In the Internet, end systems are connected together by ( ).A copper wireB coaxial cableC communication linksD fiber optics20．End systems access to the Internet through its ( ).A modemsB protocolsC ISPD sockets21．End systems, packet switches, and other pieces of the Internet, run ( ) that control thesending and receiving of information within the Internet.A programsB processesC applicationsD protocols22．There are many private networks, such as many corporate and government networks, whose hosts cannot exchange messages with hosts outside of the private network. These private networks are often referred to as ( ).A internetsB LANC intranetsD WAN23．The internet allows ( ) running on its end systems to exchange data with each other.A clients applicationsB server applicationsC P2P applicationsD distributed applications24．The Internet provides two services to its distributed applications: a connectionlessunreliable service and () service.A flow controlB connection-oriented reliableC congestion controlD TCP25．It defines the format and the order of messagesexchanged between two or more communicatingentities, as well as the actions taken on the transmission and/or receipt of a message orother event. The sentence describes ( ).A InternetB protocolC intranetD network26．In the following options, which does not define in protocol? ( )A the format of messages exchanged betweentwo or more communicating entitiesB the order of messages exchanged betweentwo or more communicating entitiesC the actions taken on the transmission ofa message or other eventD the transmission signals are digitalsignals or analog signals27．In the following options, which is defined in protocol? ( )A the actions taken on the transmission and/orreceipt of a message or other eventB the objects exchanged between communicating entitiesC the content in the exchanged messagesD the location of the hosts28．In the following options, which does not belong to the network edge? ( )A end systemsB routersC clientsD servers29．In the following options, which belongs to the network core? ( )A end systemsB routersC clientsD servers30．In the following options, which is not the bundled with the Internet’sconnection-oriented service? ( )A reliable data transferB guarantee of the transmission timeC flow controlD congestion-control31．An application can rely on the connection to deliver all of its data without error and in the proper order. The sentence describes ( ).A flow controlB congestion-controlC reliable data transferD connection-oriented service32．It makes sure that neither side of a connection overwhelms the other side by sending too many packets too fast. The sentence describes ( ).A flow controlB congestion-controlC connection-oriented serviceD reliable data transfer33．It helps prevent the Internet from entering a state of gridlock. When a packet switch becomes congested, its buffers can overflow and packet loss can occur. The sentence describes ( ).A flow controlB congestion-controlC connection-oriented serviceD reliable data transfer34．The Internet’s connection-oriented service has a name, it is ( ).A TCPB UDPC TCP/IPD IP35．In the following options, which service does not be provided to an application by TCP?( )A reliable transportB flow controlC video conferencingD congestion control36．The Internet’s connectionless service is called ( ).A TCPB UDPC TCP/IPD IP37．In the following options, which does not use TCP?( )A SMTPB internet telephoneC FTPD HTTP38．In the following options, which does not use UDP?( )A Internet phoneB video conferencingC streaming multimediaD telnet39．There are two fundamental approaches to buildinga network core, ( ) and packet switching.A electrical current switchingB circuit switchingC data switchingD message switching40．In ( ) networks, the resources needed along a path to provide for communication between the end system are reserved for the duration of the communication session.A packet-switchedB data-switchedC circuit-switchedD message-switched41．In ( ) networks, the resources are not reserved;a session’s messages use the resources ondemand, and as a consequence, may have to wait for access to communication link.A packet-switchedB data-switchedC circuit-switchedD message-switched42．In a circuit-switched network, if each link has n circuits, for each link used by the end-to-end connection, the connection gets ( ) of thelink’s bandwidth for the duration of theconnection.A a fraction 1/nB allC 1/2D n times43．For ( ), the transmission rate of a circuit is equal to the frame rate multiplied by the number of bits in a slot.A CDMAB packet-switched networkC TDMD FDM44．( ) means that the switch must receive the entire packet before it can begin to transmit the first bit of the packet onto the outbound link.A Queuing delayB Store-and-forward transmissionC Packet lossD Propagation45．The network that forwards packets according to host destination addresses is called ( )network.A circuit-switchedB packet-switchedC virtual-circuitD datagram46．The network that forwards packets according to virtual-circuit numbers is called ( ) network.A circuit-switchedB packet-switchedC virtual-circuitD datagram47．In the following entries, which is not a kind of access network?( )A residential accessB company accessC wireless accessD local access48．Suppose there is exactly one packet switch between a sending host and a receiving host. The transmission rates between the sending host and the switch and between the switch and thereceiving host are R1 and R2, respectively.Assuming that the switch uses store-and-forward packet switching, what is the total end-to-end delay to send a packet of length L? (Ignorequeuing delay, propagation delay, andprocessing delay.) ( )A L/R1＋L/R2B L/R1C L/R2D none of the above49．The time required to examine the packet’s headerand determine where to direct the packet is part of the ( ).A queuing delayB processing delayC propagation delayD transmission delay50．The time required to propagate from the beginning of the link to the next router is ( ).A queuing delayB processing delayC propagation delayD transmission delay51．Consider sending a packet of 3000bits over a path of 5 links. Each link transmits at 1000bps. Queuing delays, propagation delay and processing delay are negligible. (6 points)(1).Suppose the network is a packet-switched virtual circuit network. VC setup time is 0.1 seconds. Suppose the sending layers add a total of 500 bits of header to each packet. How long does it take to send the file from source to destination?(2).Suppose the network is a packet-switched datagram network and a connectionless service is used. Now suppose each packet has 200 bits of header. How long does it take to send the file?(3).Suppose that the network is a circuit-switched network. Further suppose that the transmission rate of the circuit between source and destination is 200bps. Assuming 0.02s setup time and 200 bits of header appended to the packet, how long does it take to send the packet?Solution:?(1) .?t=5*(3000+500)/1000+0.1=17.6s?(2). t=5*(3000+200)/1000=16s(3). t=(3000+200)/200+0.02=16.02s。
Module-6-The-Internet-and-Telecommunications(共56张)
注册/注销
2. consist of
由……组成
3. as well
也
4. become known as ...
作为……而出名；被称为……
5. go down
下降
6. come up with
提出
7. from that moment on
从那时起
8.concentrate on
聚精会神；集中思想
pared with
7.defence n．保护；防卫→ defend vt.防护；防卫
8.create vt.创造；发明→ creation n．创造(力)→creative adj.
有创造力的
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Module 6 The Internet and Telecommunications
contain oneself
克制自己；自制
container n.
容器
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Module 6 The Internet and Telecommunications
①The Chinese diet is considered to be the healthiest in the world, containing (contain) a lot of fruit and vegetables. 中国饮食被认为是世界上最健康的，里面含有大量的水果和
5. Concentration is important for this kind of work, and only by _co_n__ce_n_t_r_a_t_in_g_on it can you get it done well.(concentrate)
Section+A+英文
4.2Section AWhat Is a Local Area Network?Para.1A local area network(LAN)is a network of connected computers in a room, building,or set of buildings.Local area networks have been around since the beginning of computer use.A LAN is defined as a user network whereby data is sent at high rates between people located close to each other.Para.2The Internet is a wide area network,or WAN,which is different from a LAN. In contrast to the term Internet,local area networks are often called Intranets,though sometimes this term refers to a bunch of LANs connected with a particular company or organization but not connected to the larger Internet.A local area network uses a hub or router to connect computers together.The means of communication is the omnipresent Ethernet cable or wireless Wi-Fi technology.These technologies offer data transfer rates running between10to10,000Mbit/s.Para.3More important LANs have extra lines or other backup protocols.In networked computers,the most popular communication protocol is TCP/IP.Smaller LANs may be temporary and used between friends to play computer games over the network.Via the network,users can view and share files,make changes to data on other computers if it is possible,play movies or music on many computers at once, chat with instant messaging,send emails to each other,play games,and so on. Para.4Perhaps the most frequent use of a LAN is to connect users to the Internet with only one connected router.In modern times,we use broadband cable or DSL modems to join to the Internet,and it would be clumsy to have a modem connected with every computer,so we simply plug the modem into a router and link the router to computers with Ethernet cables.Para.5Setting up a LAN can be challenging at first,but contemporary operating systems have programs that do most of the necessary configurations automatically, which makes the set-up much easier.。
高中英语名师导学外研版必修一课件：Module 6 The Internet and Telecommunications Section Ⅰ
In 1969, DARPA, a US defence⑦ organisation【1】，developed⑧ a way for all their computers to “talk” to each other through the telephone.They created⑨ a network⑩ of computers called DARPANET.【2】For fifteen years, only the US army could use this system of communication⑪.Then in 1984, the US National Science Foundation (NSF) started the NSFNET network.It then became possible for universities to use the system as well⑫.【3】NSFNET became known as⑬ the InterNetwork, or “Internet”．
[再记住] ①source/sɔː s/n.来源；出处 ②information / Infə'meIʃn /n.[U]信息
③accessible/ək'sesəbl /adj.可进入的；可使用的 ④consist of...由……组成 ⑤millions of 数以百万计的；无数的 ⑥data /'deItə/n.(复)数据 单数形式是 datum
First, Wyman, a reading expert, says that the use of computers can help children make progress in school and that interactive software programs help kids of all ages develop their strong points and build up their weaker areas.According to reports, some software, such as e-mail, can improve children's writing ability, too.Internet access greatly increases the number and quality of resources that children learn.
第7章_无线宽带网络
内容提要
无线宽带技术
覆盖范围较广，传输速 度较快，为物联网提供 高速可靠廉价且不受接 入设备位置限制的互联 手段。
本章将以Wi-Fi和WiMAX 为例讨论无线宽带技术。
本章内容
7.1 概述：无线网络
7.2 Wi-Fi：无线局域网 7.3 WiMAX：无线城域网 7.4 展望：无线物联世界
– 应用层协议并不是无线网络的重点，只要支持 传统的应用层协议即可，当然对于一些特殊的 网络和特殊应用，也要对其进行一定的规范化
无线局域网概述
• 无线局域网是指在一个局部区域内计算机通过无 线链路进行通信的网络
• 按照拓扑结构可分为 ✓ 带基站的无线网络（基础结构无线网络） ✓ Ad Hoc 网络（自组织网络）
– 美国联邦通信委员会（FCC）限制了可用频率的数量， 使一个服务区最多只能同时进行23个电话交谈
– 相邻信道干扰也使通话质量非常糟糕
– AT&T公司只能把部分申请人暂时放在等候名单上
• 1976年，纽约市只有不到600名移动电话用户，申请 者超过了3500人
• 整个美国有45000名用户，但仍有20000个申请者在 等待，其中最长的已经等了10年之久
• 蜂窝技术经历了漫长的发展之路：
– 早期使用800MHz频率来传递模拟信号 – 随后出现的个人通信服务（PCS）使用
1850MHz的频率
• Sprint公司是PCS服务的主要提供商
– 一些移动运营商也开始使用数字技术:
• TDMA—时分多址 • CDMA—码分多址 • GSM—全球移动通信系统 • 3G —(WCDMA、CDMA2000、TD-SCDMA) • 4G？！……
Networks
大工14春《专业英语(计算机英语)》在线测试3答案
大工14春《专业英语（计算机英语）》在线测试3判断题单选题一、判断题（共10 道试题，共20 分。
）1. An online payment is a monetary transcation from the customer to the vendor over the Internet by credit card, digital cash, e-wallets, and smart cards.( )A. 错误B. 正确-----------------选择：B2. A leased line is a line rented from a telephone company for the exclusive use of a customer to access Internet.( )A. 错误B. 正确-----------------选择：B3. To access the Web, users require a Web browser ,which is the software program used to access the World Wide Web.（）A. 错误B. 正确-----------------选择：B4. A Domain Name System is an Internet service that translates domain names to or from IP addresses.( )A. 错误B. 正确-----------------选择：B5. Electronic Commerce means buying and selling products and services online via the Internet.( )A. 错误B. 正确-----------------选择：B6. EDI is a set of computer interchange standards for business documents such as invoices, bills, and purchase orders.( )A. 错误B. 正确-----------------选择：B7. FTP is the messages, usually text, send from one person to another via the Internet.（）A. 错误B. 正确-----------------选择：A8. To protect data, you need to implement a data backup and recovery plan.（）A. 错误B. 正确。
高考话题四 Topic 1 The Internet and Telecommunications(Book 1
高考话题四科普知识与现代技术Topic 1 The Internet and Telecommunications(Book 1·Module 6)Ⅰ.阅读理解A话题词数建议用时互联网291 8分钟popular now. Whether cable or mobile broadband, today's connections are many times faster than those in the early days. Videos play smoothly, complex websites load quickly, and files download much faster than ten years ago. And the files are much bigger too.There's a hidden problem: you have to live near enough to amajor city to get broadband Internet. If you don't, it's slow dial-upaccess for you. And for those living really far away, there may be noInternet access at all.Technology experts often talk about the “last mile”problem, which refers to the difficulty of bringing Internet access to remote locations. In cities and suburbs (郊区), it's relatively easy to provide access for everyone. It is much more difficult to deliver access to those living far from cities, especially in developing countries. Internet service providers, for their part, have been reluctant to provide access to sparsely (稀疏地) populated areas. The handful of Internet users they would reach wouldn't cover the expense.But every year, technological advancements allow of more and more Internet users. Most broadband connections today run over existing cable TV and telephone lines although these technologies aren't available everywhere.Some companies have delivered the Internet over standard power lines. Advancements in cheaper and more efficient fiberoptic cables (光缆) promise to bring extremely fast Internet connections to more users. Still, the “last mile”problem remains hard to deal with. There will always be somewhere that doesn't have an affordable broadband connection. But someday that might not matter. If the rapid progress in cellphone technology has any indication, it may not be too long before an Internet connection simply follows you wherever you go.语篇解读：如今互联网发展迅速，这使得越来越多的人能够用上网络。
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ArchitectureforHigh-SpeedInternetAccessOverCATVNetworksintheResidentialArea*
Chiung-ShienWu,Gin-KouMa,andBao-ShuhP.LinComputerandCommunicationResearchLabs.ITRI,Hsinchu,Taiwan310,R.O.C.
May24,1996
SubjectArea:Broadbandconsumer/homeaccesstotheinternet.
*ThisworkiscurrentlysupportedbytheR.O.C.MinistryofEconomicAffairsundertheprojectNo.37H3100conductedbyITRI.ABSTRACTTheSegmentedSubnetworkArchitecture(SSA)forhighspeedinternetaccessusingtheCATV(CommunityAntennaTV)networksandthetraditionalIEEE802.3mediumaccessprotocolisdescribedinthispaper.Theproposedarchitectureisattractiveinitsadvantagesofusingtheexistinginfrastructureintheresidentialareaandthusitiscosteffectiveandwellsuitedforhomeinternetaccess.However,thetraditionalCSMA/CDprotocolisnotfitforthecableTVnetworkduetoitslongpropagationdelay.Thus,weproposetocombinetheexistingIEEE802.3CSMA/CDMACwiththesegmentedcablesubnetworkssothatahomeusercangetaccesstotheinternetjustlikeusingtheEthernetat10.Onlythreesubcarriersinthepassbandcableisusedandthereforeitwillnotinterferewiththetraditionalbroadcastingchannelsandthefuturedigitalvideochannels.ThesegmentedcableareinterconnectedbythedefinedCableBridge(CB)andasimpleflowcontrolmechanismisproposedamongtheCBs.FunctionalcomponentsandoperationsofeachCBwillalsobedescribed.
Keywords:CATVNetworks,Internet.C.S.Wu,G.K.Ma,...:ArchitectureforHigh-SpeedInternetAccess...1
1IntroductionInternetservicesarebecomingmoreandmorepopularnotonlytothosespecialresearchers,engineers,orstudentsbutalsotoallkindsofpeoplewhomightwanttomakeconnectionstotheinternetathome.Telephonemodemshavebeenusedtoprovidethisservicetohomebuttheaccessrateislimitedtoonlyseveraltensof.Anothersolutionusingcablemodemoverthe
existingCATVnetworksisreceivingmuchattentionintheindustry.CATVnetworkisthemostimportantcandidatefordeliveringintegratedservicestothesubscribersasitisalreadyinstalledatmostofthefamilieswithaveryhighbandwidthavailable[1].Itcanprovidemultiplechannelsinasinglecabletocarryanalogordigitalsignals.Hence,itservesasagoodinfrastructuretoconnectthelargenumberofhomeuserswhomaybeusingthemultimediaservice,videobroadcastingservice,voiceservice,andtheinternetservice[2],[3].Manyvendershavebeendevotedtothedesignandmanufactureofthecablemodemwhichisintendedforthedataaccessoverthecable.TheCATVnetworkusesatree-and-branchtopologysuchthatthenumberofusersonthenetworkisgrowable,asshowninFigure1.Someamplifiersandsplittersarerequiredtoextendthetreetoeachhomeuserintheresidentialarea.AheadendislocatedattheendofthecableanditservesasagatewaybetweenthecableandothersignalsourcessuchasATM(AsynchronousTransferMode)backboneorthesatellitechannels.Thecableisconfiguredasamulti-channelbususingthefrequencydivisionmultiplexing(FDM)technology[4],[5].Eachchannelisreferredtoasasubcarrierwhichusesapassbandofthefrequencyoffsetinthefrequencyspectrumofthecable.DigitaldatatransmissioncanbeachievedoneachsubcarrierbysomemodulationmethodssuchasQPSK(QuadraturePhaseShiftKeying)orQuadratureAmplitudeModulation(QAM).Fortwo-waydataservices,somesubcarriersaredefinedastheupstreamchannelsforcablemodemstransmittingtheirdatauptotheheadendandsomeothersubcarriersaredefinedasthedownstreamchannelsforheadendtransmittingdatadowntoeachcablemodem.Forsimplicity,aCATVnetworkisusuallyrepresentedbyalogicaldualbusstructureasshowninFigure2.Sinceeachsubcarrierisabroadcastmedium,therearecontentionproblemsintheupstreamchannelwhenmultiplecablemodemswishtotransmitonthechannelsimultaneously.C.S.Wu,G.K.Ma,...:ArchitectureforHigh-SpeedInternetAccess...2
Severalmediumaccessmethodshavebeenproposedforthetwo-wayservicesovertheCATVnetworks[6],[7],[8].MostoftheproposedmethodsusecontentionresolutionschemessuchasALOHAtoresolvethecollisionamongmultiplecablemodems.However,theschemescouldbemorecomplicatedifonewantstoobtainhighthroughputinbroadcastingchannelswithlongpropagationdelay,i.e.,usingthetreeresolutionalgorithm[9].Meanwhile,standardizationactivityhasbeenundertakenbyIEEE802.14project[10]andDAVIC(DigitalAudioVisualCouncil)[11].Itusuallytakesalongtimeforthestandardprocesstobeformallyfinalized.Andeventhestandardhavingbeenreleased,itisquiteuncertainwhetherthestandardprotocolwillbewidelyusedornot.Besides,thedevelopmentofanewprotocoliscostlyandtime-consuming.Inthispaper,weproposetousethetraditionalIEEE802.3CSMA/CDprotocolovertheexist-ingcablenetworkswhilemaintainingthetransmissionrateat10.SincethegeographicalsizeofaresidentialareaisquitelargerthanthemaximumsegmentsizeoftheEthernet,thecableisconfiguredbythedividingthecableintosegmentswhichwerefertoastheSegmentSubnetworkArchitectureoverCATVnetworks(SSA-CATVnetworks).Theproposedarchitec-tureisattractiveinitsadvantagesofusingtheexistinginfrastructureintheresidentialareaandthusitiscosteffectiveandwellsuitedforhomeinternetaccess.Theproposedscenarioisachievedbyusingonlythreesubcarriersinthepassbandcablewithoutinterferingwiththetraditionalbroadcastingchannelsandthefuturedigitalvideochannels.ThesegmentedcableareinterconnectedbythedefinedCableBridge(CB).FlowcontrolmechanismisrequiredbetweentwoCBs.FunctionalcomponentsandoperationsofeachCBwillalsobedescribedinthispaper.Therestofthispaperisorganizedasfollows.SomechallengingissuesregardingtodataaccessoverCATVnetworksforhomeusersaredescribedinSection2.TheproposedSSA-CATVarchitectureandthedesignofacablebridgeisdescribedinSections3and4,respectively.QueueingbehaviorandsomeperformanceconsiderationsaregiveninSections5and6.TheflowcontrolschemeisdescribedinSection7andfinallyashortconclusionisgiveninSection8.