第一篇：十大信譽(yù)單位英文翻譯

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第二篇：常用英文翻譯十大技巧

常用英文翻譯十大技巧

作者:netboy 日期:2007-07-27 字體大小: 小 中 大

英漢兩種語(yǔ)言在句法、詞匯、修辭等方面均存在著很大的差異，因此在進(jìn)行英漢互譯時(shí)必然會(huì)遇到很多困難，需要有一定的翻譯技巧作指導(dǎo)。常用的翻譯技巧有增譯法、省譯法、轉(zhuǎn)換法、拆句法、合并法、正譯法、反譯法、倒置法、包孕法、插入法、重組法和綜合法等。這些技巧不但可以運(yùn)用于筆譯之中，也可以運(yùn)用于口譯過(guò)程中，而且應(yīng)該用得更加熟練，因?yàn)榭谧g工作的特點(diǎn)決定了譯員沒(méi)有更多的時(shí)間進(jìn)行思考。

一、增譯法

指根據(jù)英漢兩種語(yǔ)言不同的思維方式、語(yǔ)言習(xí)慣和表達(dá)方式，在翻譯時(shí)增添一些詞、短句或句子，以便更準(zhǔn)確地表達(dá)出原文所包含的意義。這種方式多半用在漢譯英里。漢語(yǔ)無(wú)主句較多，而英語(yǔ)句子一般都要有主語(yǔ)，所以在翻譯漢語(yǔ)無(wú)主句的時(shí)候，除了少數(shù)可用英語(yǔ)無(wú)主句、被動(dòng)語(yǔ)態(tài)或“There be…”結(jié)構(gòu)來(lái)翻譯以外，一般都要根據(jù)語(yǔ)境補(bǔ)出主語(yǔ)，使句子完整。英漢兩種語(yǔ)言在名詞、代詞、連詞、介詞和冠詞的使用方法上也存在很大差別。英語(yǔ)中代詞使用頻率較高，凡說(shuō)到人的器官和歸某人所有的或與某人有關(guān)的事物時(shí)，必須在前面加上物主代詞。因此，在漢譯英時(shí)需要增補(bǔ)物主代詞，而在英譯漢時(shí)又需要根據(jù)情況適當(dāng)?shù)貏h減。英語(yǔ)詞與詞、詞組與詞組以及句子與句子的邏輯關(guān)系一般用連詞來(lái)表示，而漢語(yǔ)則往往通過(guò)上下文和語(yǔ)序來(lái)表示這種關(guān)系。因此，在漢譯英時(shí)常常需要增補(bǔ)連詞。英語(yǔ)句子離不開(kāi)介詞和冠詞。另外，在漢譯英時(shí)還要注意增補(bǔ)一些原文中暗含而沒(méi)有明言的詞語(yǔ)和一些概括性、注釋性的詞語(yǔ)，以確保譯文意思的完整?？傊?，通過(guò)增譯，一是保證譯文語(yǔ)法結(jié)構(gòu)的完整，二是保證譯文意思的明確。如：

①、What about calling him right away? 馬上給他打個(gè)電話，你覺(jué)得如何？（增譯主語(yǔ)和謂語(yǔ)）

②、If only I could see the realization of the four modernizations.要是我能看到四個(gè)現(xiàn)代化實(shí)現(xiàn)該有多好啊?。ㄔ鲎g主句）

③、Indeed, the reverse is true.實(shí)際情況恰好相反。（增譯名詞）

④、就是法西斯國(guó)家本國(guó)的人民也被剝奪了人權(quán)。

Even the people in the fascist countries were stripped of their human rights.（增譯物主代詞）

⑤、只許州官放火，不許百姓點(diǎn)燈。

While the magistrates were free to burn down house, the common people were forbidden to light lamps.（增譯連詞）

⑥、這是我們兩國(guó)人民的又一個(gè)共同點(diǎn)。

This is yet another common point between the people of our two countries.（增譯介詞）

⑦、在人權(quán)領(lǐng)域，中國(guó)反對(duì)以大欺小、以強(qiáng)凌弱。

In the field of human rights, China opposes the practice of the big oppressing the small and the strong bullying the weak.（增譯暗含詞語(yǔ)）

⑧、三個(gè)臭皮匠，合成一個(gè)諸葛亮。

Three cobblers with their wits combined equal Zhuge Liang the mastermind.（增譯注釋性詞語(yǔ)）

二、省譯法

這是與增譯法相對(duì)應(yīng)的一種翻譯方法，即刪去不符合目標(biāo)語(yǔ)思維習(xí)慣、語(yǔ)言習(xí)慣和表達(dá)方式的詞，以避免譯文累贅。增譯法的例句反之即可。又如：

①、You will be staying in this hotel during your visit in Beijing.你在北京訪問(wèn)期間就住在這家飯店里。（省譯物主代詞）

②、I hope you will enjoy your stay here.希望您在這兒過(guò)得愉快。（省譯物主代詞）

③、中國(guó)政府歷來(lái)重視環(huán)境保護(hù)工作。

The Chinese government has always attached great importance to environmental protection.（省譯名詞）

三、轉(zhuǎn)換法

指翻譯過(guò)程中為了使譯文符合目標(biāo)語(yǔ)的表述方式、方法和習(xí)慣而對(duì)原句中的詞類、句型和語(yǔ)態(tài)等進(jìn)行轉(zhuǎn)換。具體的說(shuō)，就是在詞性方面，把名詞轉(zhuǎn)換為代詞、形容詞、動(dòng)詞；把動(dòng)詞轉(zhuǎn)換成名詞、形容詞、副詞、介詞；把形容詞轉(zhuǎn)換成副詞和短語(yǔ)。在句子成分方面，把主語(yǔ)變成狀語(yǔ)、定語(yǔ)、賓語(yǔ)、表語(yǔ)；把謂語(yǔ)變成主語(yǔ)、定語(yǔ)、表語(yǔ)；把定語(yǔ)變成狀語(yǔ)、主語(yǔ)；把賓語(yǔ)變成主語(yǔ)。在句型方面，把并列句變成復(fù)合句，把復(fù)合句變成并列句，把狀語(yǔ)從句變成定語(yǔ)從句。在語(yǔ)態(tài)方面，可以把主動(dòng)語(yǔ)態(tài)變?yōu)楸粍?dòng)語(yǔ)態(tài)。如：

①、我們學(xué)院受教委和市政府的雙重領(lǐng)導(dǎo)。

Our instituteis co-administrated by the States Education Commission and the municipal government.（名詞轉(zhuǎn)動(dòng)詞）

②、Too much exposure to TV programs will do great harm to the eyesight of children.孩子們看電視過(guò)多會(huì)大大地?fù)p壞視力。（名詞轉(zhuǎn)動(dòng)詞）

③、由于我們實(shí)行了改革開(kāi)放政策，我國(guó)的綜合國(guó)力有了明顯的增強(qiáng)。

Thanks to the introduction of our reform and opening policy, our comprehensivenational strength has greatly improved.（動(dòng)詞轉(zhuǎn)名詞）

④、I’m all for you opinion.我完全贊成你的意見(jiàn)。（介詞轉(zhuǎn)動(dòng)詞）

⑤、The reform and opening policy is supported by the whole Chinese people.改革開(kāi)放政策受到了全中國(guó)人民的擁護(hù)。（動(dòng)詞轉(zhuǎn)名詞）

⑥、In his article the author is critical of man’s negligence toward his environment.作者在文章中，對(duì)人類疏忽自身環(huán)境作了批評(píng)。（形容詞轉(zhuǎn)名詞）

⑦、In some of the European countries, the people are given the biggest social benefits such as medical insurance.在有些歐洲國(guó)家里，人民享受最廣泛的社會(huì)福利，如醫(yī)療保險(xiǎn)等。（被動(dòng)語(yǔ)態(tài)轉(zhuǎn)主動(dòng)語(yǔ)態(tài)）

⑧、時(shí)間不早了，我們回去吧！We don’t have much time left.Let’s go back.（句型轉(zhuǎn)換）

⑨、學(xué)生們都應(yīng)該德、智、體全面發(fā)展。

All the students should develop morally, intellectually and physically.（名詞轉(zhuǎn)副詞）

四、拆句法和合并法

這是兩種相對(duì)應(yīng)的翻譯方法。拆句法是把一個(gè)長(zhǎng)而復(fù)雜的句子拆譯成若干個(gè)較短、較簡(jiǎn)單的句子，通常用于英譯漢；合并法是把若干個(gè)短句合并成一個(gè)長(zhǎng)句，一般用于漢譯英。漢語(yǔ)強(qiáng)調(diào)意合，結(jié)構(gòu)較松散，因此簡(jiǎn)單句較多；英語(yǔ)強(qiáng)調(diào)形合，結(jié)構(gòu)較嚴(yán)密，因此長(zhǎng)句較多。所以漢譯英時(shí)要根據(jù)需要注意利用連詞、分詞、介詞、不定式、定語(yǔ)從句、獨(dú)立結(jié)構(gòu)等把漢語(yǔ)短句連成長(zhǎng)句；而英譯漢時(shí)又常常要在原句的關(guān)系代詞、關(guān)系副詞、主謂連接處、并列或轉(zhuǎn)折連接處、后續(xù)成分與主體的連接處，以及意群結(jié)束處將長(zhǎng)句切斷，譯成漢語(yǔ)分句。這樣就可以基本保留英語(yǔ)語(yǔ)序，順譯全句，順應(yīng)現(xiàn)代漢語(yǔ)長(zhǎng)短句相替、單復(fù)句相間的句法修辭原則。如：

①、Increased cooperation with China is in the interests of the United States.同中國(guó)加強(qiáng)合作，符合美國(guó)的利益。（在主謂連接處拆譯）

②、I wish to thank you for the incomparable hospitalityfor which the Chinese people are justly famous throughout the world.我要感謝你們無(wú)與倫比的盛情款待。中國(guó)人民正是以這種熱情好客而聞明世界的。（在定語(yǔ)從句前拆譯）③、This is particularly true of the countries of the commonwealth, who see Britain’s membership of the Community a guarantee that the policies of the community will take their interests into account.英聯(lián)邦各國(guó)尤其如此，它們認(rèn)為英國(guó)加入歐共體，將能保證歐共體的政策照顧到它們的利益。（在定語(yǔ)從句前拆譯）

④、中國(guó)是個(gè)大國(guó)，百分之八十的人口從事農(nóng)業(yè)，但耕地只占土地面積的十分之一，其余為山脈、森林、城鎮(zhèn)和其他用地。

China is a large country with four-fifths of the population engaged in agriculture, but only one tenth of the land is farmland, the rest being mountains, forests and places for urban and other uses.（合譯）

五、正譯法和反譯法

這兩種方法通常用于漢譯英，偶爾也用于英譯漢。所謂正譯，是指把句子按照與漢語(yǔ)相同的語(yǔ)序或表達(dá)方式譯成英語(yǔ)。所謂反譯則是指把句子按照與漢語(yǔ)相反的語(yǔ)序或表達(dá)方式譯成英語(yǔ)。正譯與反譯常常具有同義的效果，但反譯往往更符合英語(yǔ)的思維方式和表達(dá)習(xí)慣。因此比較地道。如： ①、在美國(guó)，人人都能買到槍。

In the United States, everyone can buy a gun.（正譯）

In the United States, guns are available to everyone.（反譯）

②、你可以從因特網(wǎng)上獲得這一信息。

You can obtain this information on the Internet.（正譯）

This information is accessible/available on the Internet.（反譯）

③、他突然想到了一個(gè)新主意。

Suddenly he had a new idea.（正譯）

He suddenly thought out a new idea.（正譯）

A new idea suddenly occurred to/struck him.（反譯）④、他仍然沒(méi)有弄懂我的意思。

He still could not understand me.（正譯）

Still he failed to understand me.（反譯）

⑤、無(wú)論如何，她算不上一位思維敏捷的學(xué)生。

She can hardly be rated as a bright student.（正譯）

She is anything but a bright student.（反譯）

⑥、Please withholdthe document for the time being.請(qǐng)暫時(shí)扣下這份文件。（正譯）

請(qǐng)暫時(shí)不要發(fā)這份文件。（反譯）

六、倒置法

在漢語(yǔ)中，定語(yǔ)修飾語(yǔ)和狀語(yǔ)修飾語(yǔ)往往位于被修飾語(yǔ)之前；在英語(yǔ)中，許多修飾語(yǔ)常常位于被修飾語(yǔ)之后，因此翻譯時(shí)往往要把原文的語(yǔ)序顛倒過(guò)來(lái)。倒置法通常用于英譯漢, 即對(duì)英語(yǔ)長(zhǎng)句按照漢語(yǔ)的習(xí)慣表達(dá)法進(jìn)行前后調(diào)換，按意群或進(jìn)行全部倒置，原則是使?jié)h語(yǔ)譯句安排符合現(xiàn)代漢語(yǔ)論理敘事的一般邏輯順序。有時(shí)倒置法也用于漢譯英。如：

①、At this moment, through the wonder of telecommunications, more people are seeing and hearing what we say than on any other occasions in the whole history of the world.此時(shí)此刻，通過(guò)現(xiàn)代通信手段的奇跡，看到和聽(tīng)到我們講話的人比整個(gè)世界歷史上任何其他這樣的場(chǎng)合都要多。（部分倒置）

②、I believe strongly that it is in the interest of my countrymen that Britain should remain an active and energetic member of the European Community.我堅(jiān)信，英國(guó)依然應(yīng)該是歐共體中的一個(gè)積極的和充滿活力的成員，這是符合我國(guó)人民利益的。（部分倒置）

③、改革開(kāi)放以來(lái)，中國(guó)發(fā)生了巨大的變化。

Great changes have taken place in China since the introduction of the reform and opening policy.（全部倒置）

七、包孕法

這種方法多用于英譯漢。所謂包孕是指在把英語(yǔ)長(zhǎng)句譯成漢語(yǔ)時(shí)，把英語(yǔ)后置成分按照漢語(yǔ)的正常語(yǔ)序放在中心詞之前，使修飾成分在漢語(yǔ)句中形成前置包孕。但修飾成分不宜過(guò)長(zhǎng)，否則會(huì)形成拖沓或造成漢語(yǔ)句子成分在連接上的糾葛。如：

①、You are the representative of a country and of a continent to which China feels particularly close.您是一位來(lái)自于使中國(guó)倍感親切的國(guó)家和大洲的代表。

②、What brings us together is that we have common interests which transcend those differences.使我們走到一起的，是我們有超越這些分歧的共同利。

八、插入法

指把難以處理的句子成分用破折號(hào)、括號(hào)或前后逗號(hào)插入譯句中。這種方法主要用于筆譯中。偶爾也用于口譯中，即用同位語(yǔ)、插入語(yǔ)或定語(yǔ)從句來(lái)處理一些解釋性成分。

如：如果說(shuō)宣布收回香港就會(huì)像夫人說(shuō)的“帶來(lái)災(zāi)難性的影響”，那我們要勇敢地面對(duì)這個(gè)災(zāi)難，做出決策。

If the announcement of the recovery of Hong Kong would bring about, as Madam put it, “disastrous effects,” we will face that disaster squarelyand make a new policy decision.九、重組法

指在進(jìn)行英譯漢時(shí)，為了使譯文流暢和更符合漢語(yǔ)敘事論理的習(xí)慣，在捋清英語(yǔ)長(zhǎng)句的結(jié)構(gòu)、弄懂英語(yǔ)原意的基礎(chǔ)上，徹底擺脫原文語(yǔ)序和句子形式，對(duì)句子進(jìn)行重新組合。

如：Decision must be made very rapidly;physical enduranceis tested as much as perception, because an enormous amount of time must be spent making certain that the key figures act on the basis of the same information and purpose.必須把大量時(shí)間花在確保關(guān)鍵人物均根據(jù)同一情報(bào)和目的行事，而這一切對(duì)身體的耐力和思維能力都是一大考驗(yàn)。因此，一旦考慮成熟，決策者就應(yīng)迅速做出決策。

十、綜合法

是指單用某種翻譯技巧無(wú)法譯出時(shí)，著眼篇章，以邏輯分析為基礎(chǔ)，同時(shí)使用轉(zhuǎn)換法、倒置法、增譯法、省譯法、拆句法等多種翻譯技巧的方法。

如：How can the European Union contribute to the development of a European film and television program industry which is competitive in the world market, forward-looking and capable of radiatingthe influence of European culture and of creating jobs in Europe?

歐洲聯(lián)盟應(yīng)該怎樣做才能對(duì)歐洲的電影電視工業(yè)有所貢獻(xiàn)，使它在國(guó)際市場(chǎng)上具有競(jìng)爭(zhēng)能力，使它有能力發(fā)揮歐洲文化的影響，并且能夠在歐洲創(chuàng)造更多的就業(yè)機(jī)會(huì)呢？

歡迎光臨 http://004km.cn

第三篇：?jiǎn)挝蛔C明英文翻譯模版

單位證明

Embassy of [×××] in Beijing

[Address]

To whom it may concern,Subject: Tourist Visa Application

We certify that [Mr./Ms.××[Passport No.××] has been employed by [company name××] as a [title] since [month/year].We have approved [Mr./Ms.××]’s annual leave from [date/month/year] to

[date/month/year].[Mr./Ms.××] will resume [his/her] duties with the company on his/her return to Beijing.We are confident that [Mr./Ms.××] will return to work on time.The purpose of

[Mr./Ms.××]’s trip is only tourism.[He/She] will not seek any employment or residency in [country name: eg.Germany] and will comply with [eg.German] laws and regulations.We would be very grateful if you would approve [Mr./Ms.××]’s tourist visa application.If you have any questions, please do not hesitate to contact me on [Tel no.].Yours sincerely,[Company Name]

Sign by:[Name] and [Title]

Dated:

第四篇：英文翻譯

Introduction: with the rapid development of the economy, China ‘smprehensive national power has been improved effectively.As a saying said;“Want to become rich first road”.So China has begun to build the high-speed rail since years ago.The building of the high~speed rail is suited to China's national conditions and help our country to run well in the strong competition of the world.大多數(shù)經(jīng)濟(jì)學(xué)家認(rèn)為：交通基礎(chǔ)設(shè)施的供應(yīng)水平和能力必須適度超前，否則就會(huì)影響社會(huì)經(jīng)濟(jì)持續(xù)、穩(wěn)定 和健康發(fā)展。這就意味著要加大對(duì)交通基礎(chǔ)設(shè)施的投資，但是政府在加大交通基礎(chǔ)設(shè)施投資力度的同時(shí)，用于改善民生的措施實(shí)際卻在相對(duì)地減少。從中國(guó)目前的經(jīng)濟(jì)發(fā)展和人民的收入狀況來(lái)說(shuō)，我認(rèn)為中國(guó)高 鐵弊大于利.Most economists believe that: the supply and capability of transportation infrastructure must advance appropriately, otherwise it will affect the sustainable, stable and healthy development of social economy.This means that we have to increase the investment into transportation infrastructure,But while government increase the investment into transportation infrastructure, it will to some extent decrease the practical measures to improve people's livelihood.From China's current situation, I think it will do more harm than good to build high-speed railway in China.Piont1: Building too fast go against the laws of economic development, causing many problems, such as loan repayment, staff placement.And high-speed railway construction needs large investment, from the use of the actual situation, the possibility of short-term cost recovery do not, there is also the problem of capital wasting.建設(shè)速度過(guò)快，容易違背經(jīng)濟(jì)發(fā)展規(guī)律,同時(shí)面對(duì)的問(wèn)題較多，例如貸款償還，員工安置等。中國(guó)第一條高 鐵客運(yùn)專線——從北京到天津，它在 2008 年 8 月通車后一年就虧損了 7 個(gè)億。武廣高鐵總投資約 1166 億元，目前的線路至少能開(kāi) 120 對(duì)車，但實(shí)際上只開(kāi)了 33 對(duì)，而且還坐不滿，這是資本的嚴(yán)重浪費(fèi)。所 以說(shuō)高鐵建設(shè)不僅需要大筆的投資，而且從運(yùn)用的實(shí)際的情況來(lái)看，短期收回成本的可能性根本就沒(méi)有。The fast building speed will violate the rule of economic development, and at same time it faced many problems, such as loan repayment, staff placement.First high-speed railway of China-from Beijing to Tianjin, it was launched in August 2008, after one year it lossed 70 millions.The total investment of

Wuhan-Guangzhou high-speed rail was about 110 billions yuan, now it is able to drive at least 120 pairs of cars, but in fact only 33 to drive, and lots of seats are empty, this is a serious waste of capital.The high-speed railway not only requires large construction investment, but also, it is impossible to recovery the short-term cost based on its actural implement.Poiimnt2: The building of the high spee

d rail can drive the development of the industry related.for example, the building need many workers and the new technology, so it expand the employment and promiot the technological innovation.In another word through the building, more steel products are needed.Another important hand is transport during the Spring Festival.During this period of time, large numbers of people going home together.So the high speed rail can relieve the transportation pressure ectively 高鐵的票價(jià)較高，例如京津高鐵，它行駛 30 分鐘，卻要 69 元票價(jià)，讓人望而生嘆啊。中國(guó)的 GDP 總量 高居世界第二，但人均 GDP 在世界的排名卻還在百名開(kāi)外，窮人還是絕大多數(shù)。武廣高鐵開(kāi)通后，原有 的一些客運(yùn)列車停運(yùn)，意味著中低收入者將被迫選擇高鐵，接受高票價(jià)。這種行為傷及了底層人民的最根 本利 e 而且建設(shè)過(guò)程中容易出現(xiàn)貪污腐敗問(wèn)題。The fare of high Speed Rail is higher, for example, the Beijing-Tianjin high-speed rail, it costs 69 yuan for only drive 30minuts.China's GDP ranks the second in the world, but per capita GDP still ranks out of hundreds in the world, the poor is the majority.When Wuhan-Guangzhou high-speed railway was used, the original passenger trains were stopped, which means low-incomer will be forced to choose high-speed rail and accept the high fares.This action has

impair interests of the low class people, and the corruption problem will be prone to easily during the process of building.新建高鐵實(shí)際是在現(xiàn)有幾種交通方式的基礎(chǔ)上新增一種交通方式。建成之后會(huì)與高速公路、現(xiàn)有鐵路、飛 機(jī)、船運(yùn)形成競(jìng)爭(zhēng)關(guān)系，在原有運(yùn)力并不緊張的背景下必然形成運(yùn)力過(guò)剩。新建的高鐵主要是客運(yùn)專線，因此高鐵并不會(huì)加快貨物與資金的周轉(zhuǎn)速度，不會(huì)降低全社會(huì)運(yùn)行成本。要修建如此龐大的高速鐵路網(wǎng)，必將消耗大量的資金，必將擠占人們收入上漲的空間與企業(yè)利潤(rùn)空間（加重稅負(fù)）如果將此財(cái)政投入醫(yī)療、。社保、教育、技術(shù)研究，則會(huì)消除人們存錢的預(yù)防養(yǎng)老動(dòng)機(jī)從而擴(kuò)大消費(fèi)，利于中國(guó)經(jīng)濟(jì)可持續(xù)發(fā)展。綜 上所述，在中國(guó)大規(guī)模修建高鐵對(duì)中國(guó)經(jīng)濟(jì)的長(zhǎng)遠(yuǎn)發(fā)展來(lái)講是弊大于利，不利于擴(kuò)大內(nèi)需、不利于產(chǎn)業(yè)結(jié) 構(gòu)調(diào)整 結(jié)論：The high-speed railway will compete with the existing highway, railway, aircraft, shipping after it consummation which will lead to a situation capacity.The new high-speed railway is mainly to carry passenger, so it will not speed up the turnover rate between cargos and the capital and will not decrease the costs of the whole social transportation.To build such a large network of high-speed rail will need a large amount of money, the government must increase the taxes of people and enterprise to raise the capital.If this financial investment used in health care, social security, education, tec

第五篇：英文翻譯

Overview of the Global System for Mobile Communications 1 History of GSM During the early 1980s, analog cellular telephone systems were experiencing rapid growth in Europe, particularly in Scandinavia and the United Kingdom, but also in France and Germany.Each country developed its own system, which was incompatible with everyone else’s in equipment and operation.This was an

undesirable situation, because not only was the mobile equipment limited to operation within national boundaries, which in a unified Europe were increasingly unimportant, but there was also a very limited market for each type of equipment, so economies of scale and the subsequent savings could not be realized.The Europeans realized this early on, and in 1982 the Conference of European s Posts and Telegraphs(CEPT)formed a study group called the Group Special Mobile(GSM)to study and develop a pan-European public land mobile system.The proposed system has to meet certain criteria: ·Good subjective speech quality ·Low terminal and service cost ·Support for international roaming ·Ability to support handheld terminals ·Support for range of new services and facilities ·Spectral efficiency ·ISDN compatibility In 1989, GSM responsibility was transferred to the European Telecommunication Standards Institute(ETSI), and phase I of the GSM specifications were published in 1990.Commercial service was started in mid-1991, and by 1993 there were 36 GSM networks in 22 countries.Although standardized in Europe, GSM is not only a European standard.Over 200 GSM networks are operational in 110 countries around the world.In the beginning of 1994, there were 1.3 million subscribers worldwide, which had grown to more than 55 million by October 1997.With North America making a delayed entry into the GSM field with a derivative of GSM called PCS1900, GSM systems exist on every continent, and the acronym GSM now aptly stands for Global System for Mobile communications.The developers of GSM chose an unproven(at the time)digital system, as opposed to the then-standard analog cellular systems like AMPS in the United States and TACS in the United Kingdom.They had faith that advancements in compression algorithms and digital signal processors would allow the fulfillment of the original criteria and the continual improvement of the system in terms of quality and cost.The over 8,000 pages of GSM recommendations try to allow flexibility and competitive innovation among suppliers, but provide enough standardization to guarantee proper interworking between the components of the system.This done by providing functional and interface descriptions for each of the functional entities defined in the system.2 General Concepts 2.1 Analog Versus Digital Telephony Systems First-generation systems were analog.During the early 1980s these underwent rapid development in Europe.Although the NMT system was used by all the Nordic countries, and the TACS system in the United Kingdom and Italy, there was a variety of systems and no compatibility among them.Compared with these systems, the main advantages offered by GSM, which is the most important of the second-generation digital systems, are: ·Standardization;·Capacity;·Quality;·Security.Standardization guarantees compatibility among systems of different countries, allowing subscribers to use their own terminals in those countries that have adopted the digital standard.The lack of standardization in the first-generation system limited service to within the borders of a country.Mobility is improved, since roaming is no longer limited to areas covered by a certain system.Calls can be charged and handled using the same personal number even when the subscriber moves from one country to another.Standardization also allows the operator to buy entities of the network from different vendors, since the functional elements of the network and the interfaces between these elements are standardized.This means that a mobile phone from any manufacturer is able to communicate with any network, even if this network is built with entities from different vendors.This leads to a large economy of scale and results in cost reduction for both the operator and the subscriber.Furthermore, the phone cost is also reduced, because GSM is an international standard, produced quantities are greater and the level of competition is high.With respect to capacity, the use of the radio resource is much more efficient in a digital system such as GSM than in an analog system.This means that more users can be allocated in the same frequency bandwidth.This is possible with the use of advanced digital techniques, such as voice compression algorithms, channel coding, and multiple access techniques.Note that capacity gains are also achieved with radio frequency reuse, which had also used in analog systems.Frequency reuse means that a given carrier can be employed in different areas.The quality in digital transmission systems is better, thanks to the channel coding schemes that increase the robustness in the face of noise and disturbances such as interference caused by other users or other systems.The quality improvement is also due to the improved control of the radio link, and adaptations to propagation conditions, with advanced techniques such as power control or frequency hopping.This will be explained in greater detail in the next section.In terms of security, powerful authentication and encryption techniques for voice and data communications are enabled with GSM, which guarantees protected access to the network, and confidentiality.2.2 Cellular Telephony In mobile radio systems, one of the most important factors is the frequency spectrum.In order to make the best use of the bandwidth, the system is designed by means of the division of the service area into neighboring zones, or cells, which in theory have a hexagonal shape.Each cell has a Base Transceiver Station(BTS), which to avoid interference operates on a set of radio channels different from those of the adjacent cells.This division allows for the use of the same frequencies in nonadjacent cells.A group of cells that as a whole use the entire radio spectrum available to the operator is referred to as a cluster.The shape of a cell is irregular, depending on the availability of a spot for the BTS, the geography of the terrain, the propagation of the radio signal in the presence of obstacles, and so on.In dense urban areas, for instance, where the mobile telephony traffic is important, the diameter of the cells is often reduced in order to increase capacity.This is allowed since the same frequency channels are used in a smaller area.On the other hand, reducing the cell diameter leads to a decrease in the distance necessary to reuse the frequencies(that is, the distance between two co-channel cells), increasing co-channel interference.In order to minimize the level of interference, several techniques are used on the radio interface.A basic example of cluster organization is shown in Figure 1.In this example, we see a reuse attern for seven different frequencies, f1 to f7.These frequencies correspond to the beacon carrier of each cell, on which signaling information about the cell is broadcast(see Section 2.7).It can be seen from this figure that a given carrier can be reused in two separate geographical areas, as long as these areas are far enough from each other to reduce the effect of interference.With this technique of dividing the area in cells and clusters, the operator can increase the area it is able to cover with a limited frequency bandwidth.Figure 1 Example of a Cell Planning

在80 年代初期期間，模式手機(jī)系統(tǒng)在歐洲體驗(yàn)迅速增長(zhǎng)，特別在斯堪的那

維亞和英國(guó)，以及法國(guó)和德國(guó)。每個(gè)國(guó)家開(kāi)發(fā)了它自己的系統(tǒng)，在設(shè)備和操作 上是互不相容的。這是一個(gè)不受歡迎的情況，因?yàn)椴粌H移動(dòng)通信設(shè)備被限制在國(guó) 界之內(nèi)，這在統(tǒng)一的歐洲是越來(lái)越不重要的，而且每種類型的設(shè)備都只有一個(gè)非 常有限的市場(chǎng)，因此經(jīng)濟(jì)尺度及隨后的儲(chǔ)蓄不可能體會(huì)。

歐洲人早就意識(shí)到了這點(diǎn)，并且在1982 年歐洲郵電管理聯(lián)合會(huì)(CEPT)上形 成了移動(dòng)通信特別研究組(GSM)來(lái)研發(fā)一個(gè)能在全歐洲大陸通用的移動(dòng)通信系 統(tǒng)。提出的系統(tǒng)必須符合以下標(biāo)準(zhǔn)： 〃通話質(zhì)量好

〃終端及服務(wù)費(fèi)用低 〃支持國(guó)際漫游

〃能夠支持可隨身攜帶的終端 〃支持一系列新的服務(wù)和設(shè)備 〃效率高

〃與ISDN 兼容

1989 年，GSM 的責(zé)任轉(zhuǎn)移了到歐洲電信標(biāo)準(zhǔn)學(xué)院(ETSI)，并且GSM 規(guī)格的

第一階段也在1990 年出版了。商業(yè)服務(wù)在1991 年中期開(kāi)始了，截至1993 年有 36 個(gè)GSM 網(wǎng)絡(luò)在22 個(gè)國(guó)家誕生了。GSM 不僅僅是歐洲標(biāo)準(zhǔn)，盡管它是在歐洲 規(guī)范化的?，F(xiàn)已有200 多個(gè)GSM 網(wǎng)絡(luò)在全球110 個(gè)國(guó)家和地區(qū)運(yùn)行。1994 年初 期全球有1,300,000 用戶，截至1997 年10 月已突破55,000,000 用戶。隨著美國(guó)

后來(lái)在GSM 領(lǐng)域制造了一個(gè)詞條PCS1900 作為GSM 的拓展,GSM 系統(tǒng)已發(fā)展至 各大洲,并且縮寫(xiě)詞GSM 現(xiàn)在已可以代表移動(dòng)通信的全局系統(tǒng)。

GSM 開(kāi)發(fā)商選擇了一個(gè)當(dāng)時(shí)未經(jīng)證明的數(shù)字系統(tǒng)，與后來(lái)的標(biāo)準(zhǔn)模式蜂窩系 統(tǒng)相對(duì)，就象美國(guó)叫AMPS，而英國(guó)叫TACS 一樣。他們堅(jiān)信能夠推進(jìn)壓縮算法 和數(shù)字信號(hào)處理器使其能夠根據(jù)質(zhì)量和費(fèi)用將原始標(biāo)準(zhǔn)和系統(tǒng)連續(xù)改善。GSM 推薦8,000 頁(yè)設(shè)法使得在與供應(yīng)商競(jìng)爭(zhēng)之中體現(xiàn)靈活性和創(chuàng)新，但提供 足夠的標(biāo)準(zhǔn)來(lái)保證在系統(tǒng)的組分之間適當(dāng)配合工作。完成提供功能和接口描述的 功能個(gè)體在系統(tǒng)中都有定義。

第一代系統(tǒng)是模擬的。上個(gè)世紀(jì)80 年代初期在歐洲迅速發(fā)展。雖然所有北 歐國(guó)家使用TACS 系統(tǒng)，英國(guó)和意大利使用NMT 系統(tǒng)，它們之間還有各式各樣 的系統(tǒng)不兼容。和這些系統(tǒng)相比，GSM 提供的更重要的第二代數(shù)字系統(tǒng)主要優(yōu)勢(shì) 體現(xiàn)在： 〃標(biāo)準(zhǔn)化； 〃容量； 〃質(zhì)量； 〃安全。

標(biāo)準(zhǔn)化保證了不同國(guó)家系統(tǒng)之間的兼容性，允許采取了數(shù)字化標(biāo)準(zhǔn)的國(guó)家的 訂戶使用他們自己的終端。在第一代系統(tǒng)中缺乏標(biāo)準(zhǔn)化的有限服務(wù)為在國(guó)家的邊 界之內(nèi)。流動(dòng)性被改進(jìn)，漫游不再被限制到某一系統(tǒng)包括的面積之內(nèi)。既使當(dāng)用 戶從一個(gè)國(guó)家移動(dòng)到另一個(gè)國(guó)家，電話也可以使用同一個(gè)個(gè)人號(hào)碼。因?yàn)榫W(wǎng)絡(luò)的功能元件和這些元素之間的接口被規(guī)范化，操作員可以從不同的 供營(yíng)商購(gòu)買。這意味著所有制造商的移動(dòng)電話能與任何網(wǎng)絡(luò)溝通，即使這個(gè)網(wǎng)絡(luò) 是由不同的供營(yíng)商的功能元件建立的。這為操作員和訂戶帶來(lái)費(fèi)用成本的降低。此外，電話費(fèi)用也降低了，因?yàn)镚SM 是國(guó)際標(biāo)準(zhǔn)，生產(chǎn)數(shù)量大，競(jìng)爭(zhēng)水平高。能力方面，數(shù)字系統(tǒng)如GSM 比模擬系統(tǒng)使用的無(wú)線資源更有效。這意味著 更多的用戶可以使用同一頻帶。這就有可能利用先進(jìn)的數(shù)字技術(shù)，如語(yǔ)音壓縮算 法，信道編碼和多址接入技術(shù)。請(qǐng)注意，無(wú)線電頻率復(fù)用也取得了一定增益，這 也已用于模擬系統(tǒng)。頻率復(fù)用意味著同一載波可以在不同的地區(qū)重復(fù)使用。由于這種信道編碼方案，提高了可靠性及對(duì)噪音和其他用戶或系統(tǒng)的干擾能 力，數(shù)字傳輸系統(tǒng)的質(zhì)量更好了。質(zhì)量改進(jìn)的原因還在于改善了對(duì)無(wú)線連接的控 制，并適應(yīng)傳播條件下，使用先進(jìn)的技術(shù)，如電源控制或跳頻。質(zhì)量改進(jìn)的原因 還在于使用先進(jìn)的技術(shù)如電源控制或跳頻改善了無(wú)線連接的控制,，傳播條件的適

應(yīng)性等。這些將在下文中做更詳盡的解釋。

在安全方面，GSM 具有語(yǔ)音和數(shù)據(jù)通信的強(qiáng)大的認(rèn)證和加密技術(shù)的功能，保 證了保護(hù)接入網(wǎng)絡(luò)和保密性。

在移動(dòng)通信系統(tǒng)中，一個(gè)最重要的因素就是頻譜。為了最有效地利用帶寬，系統(tǒng)設(shè)計(jì)的目的是通過(guò)基站的服務(wù)區(qū)到周邊小區(qū)，理論上是一個(gè)正六邊形。每個(gè) 小區(qū)有一個(gè)收發(fā)基站（BTS），其中，以避免相鄰小區(qū)的不同無(wú)線信道在運(yùn)行時(shí) 產(chǎn)生相互干擾。這樣可以在不相鄰的小區(qū)使用同一載頻。一組小區(qū)，作為一個(gè)整 體，給運(yùn)營(yíng)商提供整個(gè)無(wú)線電頻譜是指一個(gè)區(qū)群。小區(qū)的形狀是不規(guī)則的，這取 決于是否有現(xiàn)成的基站，地理地形，無(wú)線電信號(hào)傳播中存在的障礙，等等。例如，在人口密集的城市地區(qū)，移動(dòng)電話的通行非常重要，小區(qū)的直徑往往 會(huì)減小，以提高其通行能力。

這是允許的，因?yàn)橥活l道只在一個(gè)較小的地區(qū)內(nèi)使用。另一方面，小區(qū)直 徑的減小導(dǎo)致使用同一頻率的小區(qū)間的距離（即兩個(gè)公共通道小區(qū)間的距離）縮 小了，增強(qiáng)了各頻道之間的相互干擾。為了盡量提高抗干擾的能力，無(wú)線接口使 用了一系列技術(shù)。

一個(gè)基本的區(qū)群組織的結(jié)構(gòu)如圖1 所示。在這個(gè)例子中，我們看到了一個(gè)復(fù) 用模式的7 個(gè)不同的頻率，f1 至f7。這些頻率對(duì)應(yīng)于每個(gè)小區(qū)的信標(biāo)載波，整個(gè)

小區(qū)的信號(hào)信息就靠它們被傳播出去（見(jiàn)第2.7 節(jié)）。從圖中可以看出，某一載 波可在兩個(gè)不同的地理區(qū)域重復(fù)使用，只要這兩個(gè)地區(qū)離的足夠遠(yuǎn)，相互之間的 干擾足夠小。這一技術(shù)把地區(qū)分成小區(qū)和區(qū)群，經(jīng)營(yíng)者可以利用有限的帶寬增加 覆蓋區(qū)域的面積。