英语中英文翻译[五篇范文]

第一篇：英语中英文翻译

英语中英文翻译

第一篇：

对龙图腾的崇拜在中国大约已绵延了八千多年。中国龙是古人将鱼、蛇、马、牛等动物与云雾、雷电等自然天象集合而成的一种神物。中国龙的形成与中华民族的多元融合过程同步。在中国人的心目中，龙具有振奋腾飞、开拓变化的寓意和团结凝聚的精神。

Dragon totem worship in China has been around for the last 8,000 years.The ancients in China considered the dragon a fetish that combines animals including the fish, snake, horse and ox with cloud, thunder, lightning and other natural celestial phenomena.The Chinese dragon was formed in accordance with the multicultural fusion process of the Chinese nation.To the Chinese, the dragon signifies initiative,innovation and cohesion.第二篇：

长城是人类创造的世界奇迹之一。如果你到了中国却没去过长城，就像到了巴黎没有去看看埃菲尔铁塔，或者就像到了埃及没有去看金字塔一样。人们常说：“不到长城非好汉。”实际上，长城最初只是一些断断续续的城墙，直到秦朝统一中国后才将其连成长城。然而，今天我们看到的长城——东起山海关，西至嘉峪关——大部分都是在明代修建的。

The Great Wall is one of the wonders of the world that was created by human beings!If you come to China without climbing the Great Wall, it„s just like going to Paris without visiting the Eiffel Tower, or going to Egypt without visiting the Pyramids!Men often say, “He who does not reach the Great Wall is not a true man.” In fact, it began as independent walls for different states when it was first built, and did not become the “Great Wall” until the Qin Dynasty when the emperor united China.However, the wall we see today, starting from Shanhaiguan Pass in the east to Jiayuguan Pass in the west, was mostly built during the Ming Dynasty.第三篇：

饺子Dumplings ravioli 是深受中国人民喜爱的传统食品。相传为古代医圣张仲景发明。饺子的制作是包括： 1）擀皮、2）备馅、3）包馅水煮三个步骤。其特点是皮薄馅嫩，味道鲜美，形状独特，百食不厌。民间有“好吃不过饺子”的俗语。中国人接亲待客、逢年过节都有包饺子吃的习俗，寓意吉利。对崇尚亲情的中国人来说，“更岁交子”吃饺子，更是欢度除夕、辞旧迎新必不可少的内容。

Dumplings are one of the Chinese people‟s favorite traditional dishes.According to an ancient Chinese legend, dumplings were first made by the medical saint---Zhang Zhongjing.There are three steps involved in making dumplings: 1)make dumpling wrappers out of dumpling flour;2)prepare the dumpling stuffing;3)make dumplings and boil them.With thin and elastic dough skin, fresh and tender stuffing, delicious

taste, and unique shapes, dumplings are worth eating hundreds of times.There‟s an old saying that claims, “Nothing could be more delicious than dumplings”.During the Spring Festival and other holidays, or when treating relatives and friends, Chinese people like to follow the auspicious custom of eating dumplings.To Chinese people who show high reverence for family love, having dumplings at the moment the old year is replaced by the new is an essential part of bidding farewell to the old and ushering in the new year.第四篇：

闻名于世的丝绸之路是一系列连接东西方的路线。丝绸之路延伸6,000多公里。得名于古代中国的丝绸贸易。丝绸之路上的贸易在中国、南亚、欧洲和中东文明发展中发挥了重要作用。正是通过丝绸之路，中国的造纸、火药、指南针、印刷等四大发明才被引介到世界各地。同样，中国的丝绸、茶叶和瓷器（porcelain）也传遍全球。物质文化的交流是双向的。欧洲也通过丝绸之路出口各种商品和植物，满足中国市场的需要。

The world-renowned Silk Road is a series of routes connecting the East and the West.It extended more than 6,000 kilometers.The Silk Road was named after ancient China‟s silk trade which played an important role in the civilization development of China, South Asia, Europe and the Middle East.It was through the Silk Road that papermaking, gunpowder, compass and printing of the four great inventions of ancient China were introduced around the world.Similarly, Chinese silk, tea and porcelain spread all over the world.Europe also exported various goods and plants through the Silk Road to meet the needs of the Chinese market.第五篇：

中国园林是经过三千多年演化而成的独具一格的园林景观。它既包括为皇室成员享乐而建造的大型花园，也包括学者、商人和卸任的政府官员为摆脱嘈杂的外部世界而建造的私家花园。这些花园构成了一种意在表达人与自然之间应有的调和关系的微缩景观。典型的中国园林周围有围墙，园内有池塘、假山、树木、花草以及各种各样由弯曲的小路和走廊衔接的建筑。散步在花园中，人们可以看到一系列精心设计的景观犹如山水画卷一般展示在面前。

Chinese gardens came into being after three thousand years of evolution and unique landscape.It includes both large garden built for the royal family enjoyment, including academics, businessmen, and former government officials to get rid of the noise of the outside world and build private garden.These gardens constituted an intended to express the human and the nature should be harmonious relations between miniature landscape.A typical Chinese garden surrounded by a fence, garden with ponds, rockeries, trees, flowers and plants, and various buildings connected by winding paths and corridors.Stroll in the garden, people can see a series of carefully designed like landscape picture show in front of the landscape.第六篇：

中国人自古以来就在中秋时节庆祝丰收，这与北美地区庆祝感恩节的习俗十分相似，过中秋节的习俗与唐代早期在中国各地开始流行，中秋节在农历八月十五，是人们拜月的节日，这天夜晚皓月当空，人们合家团聚，共赏明月。2006年，中秋节被列为中国的文化遗产，2008年又被定为公共假日，月饼被视为中秋节不可或缺的美食，人们将月饼作为礼物馈赠亲友或在家庭聚会上享用。传统的月饼上带有“寿”(longevity)、“福”或“和”等字样。

Since ancient times, the Chinese people usually celebrate harvest in the Mid-Autumn, which is similar to the custom of celebrating Thanksgiving in the North America.The tradition of celebrating Mid-Autumn festival became popular throughout China in the early Tang dynasty.The lunar August 15 is a day for people worshiping the moon.On this day, under the dazzling bright moon, families reunite and enjoy the moon‟s beauty.In 2006, Mid-Autumn festival was listed as one of China's cultural heritage, and in 2008, it was classified as a public holiday.Moon cakes, as indispensable delicious food of the festival, were gifts people sent to families and friends during the festival and usually eaten on family gatherings.There are characters of “longevity”，“good fortune”and “harmony” on the Traditional moon cakes.

第二篇：英语短文中英文翻译

1.Today my friend and I are taking a walk.suddenly, we are seeing a boy sit on the chair,he is crying,we go and ask him.“what’s the matter with you” he tell us“I can’t find my dog can you help me”.“yes,I can”.And we help him find his dong.oh it stay under the big tree!今天我和我的朋友一起去散步。突然我们看见一个男孩坐在椅子上，他哭的很伤心。我们走过去问他：“你怎么了”。他告诉我们：“我的狗不见了，你们能帮我找到它吗”。“是的，我们能帮你找到你的狗”然后我们帮助他找到了他的狗，原来是它呆在一棵大树下。2.One day an old man siselling a big elephant.A young man comes to the elephant and begins to look at it slowly.The old man goes up to him and says inhis ear,“Don't say anything about the elephant before I sell it,then i'll give you some money.”“All right,”says the young man.After the old man slles the elephant,he gives the young man some money and says,“Now,can you tell me how you find the bad ears of theelephant?”“I don't find the bad ears,”says the young man.“Then why do you look at the elephant slowly?”asks the old man.The young man answers,“Because I never see an elephant before,and I want to know what it looks like.”

一天，一个老的男人正在卖一头大象。一个年轻的男人走向大象然后开始慢慢看着它（大象），这个老的男人走向他对着他的耳朵说，“不要在我卖出它（大象）之前说关于它（大象）的事，然后我会给你一些钱。”“好的”，这个年轻的男人说。在这个老的男人卖出大象后，他给了年轻的男人一些钱并且说，“现在，你可以告诉我你是怎样知道大象的坏的耳朵了吧？”“我不知道坏的耳朵”，这个年轻的男人说。“然后为什么你慢慢的看着大象？”这个老的男人问。这个年轻的男人回答，“因为我在这之前从来没有见过大象，还有我想知道它（大象）是什么样子的。”

3.An old woman had a cat.The cat was very old;she could not run quickly, and she could not bite, because she was so old.One day the old cat saw a mouse;she jumped and caught the mouse.But she could not bite it;so the mouse got out of her mouth and ran away, because the cat could not bite it.Then the old woman became very angry because the cat had not killed the mouse.She began to hit the cat.The cat said, “Do not hit your old servant.I have worked for you for many years, and I would work for you still, but I am too old.Do not be unkind to the old, but remember what good work the old did when they were young.” 一位老妇有只猫，这只猫很老，它跑不快了，也咬不了东西，因为它年纪太大了。一天，老猫发现一只老鼠，它跳过去抓这只老鼠，然而，它咬不住这只老鼠。因此，老鼠从它的嘴边溜掉了，因为老猫咬不了它。

于是，老妇很生气，因为老猫没有把老鼠咬死。她开始打这只猫，猫说：“不要打你的老仆人，我已经为你服务了很多年，而且还愿意为你效劳，但是，我实在太老了，对年纪大的不要这么无情，要记住老年人在年青时所做过的有益的事情。”

4.I love my family, because I have a happy family.My father is an English teacher.His name is Jacky.He is thirty-eight.He likes playing basketball.What’s my mother job? Is she a teacher? Yes, you’re right!My mother is very kind and nice, she is thirty-seven.My mother is always laborious work.I love my parents!On Saturday and Sunday, I often go to the library and play the piano, My father go to play basketball.Sometimes, we watch TV and listen to music at home.I love my family.Because I’m very happy to live with my parents together!我爱我的家庭,因为我有一个快乐的家庭.我的爸爸是一名英语教师,他的名字叫Jacky.他今年38岁.他非常喜欢打篮球.我的妈妈是赶什么呢?她是一名教师吗?是的.你说对了!我的妈妈是一个很亲切、友善的人,她今年37岁.我妈妈总是勤劳的干活.我爱我的父母.在星期六和星期天里,我经常去图书馆和弹钢琴.我爸爸去打篮球.有时侯,我们都在家看电视和听音乐.我爱我家.因为我和爸爸妈妈一起生活得很开心!4.This is my room.Near the window there is a desk.I often do my homework at it.You can see some books, some flowers in a vase, a ruler and a pen.On the wall near the desk there is a picture of a cat.There is a clock above the end of my bed.I usually put my shoe under my bed.Of course there is a chair in front of the desk.I sit there and I can see the trees and roads outside.这是我的房间。在窗口附近有一张书桌。我经常在那做我的家庭作业。您能看有些书，有些花在花瓶里，一把格尺和笔。在墙壁在书桌有猫的图片。有一个时钟在我的床上的末端。我通常把我的鞋子放在我的床下。当然有一把椅子在书桌前面。我坐那里，并且我能看外面的树和路

6.What do you know about the sea? Some people know about it, but others don’t.The sea looks beautiful on a fine sunny day, the sea is very big.In the world, there is more sea than land.Do you know Hainan Island? It’s really very nice.We can see beaches, trees and the sea.We can swim and visit a lot of beautiful places.海

你对海知道些什么？ 某些人知道关于它，但其他不。海看起来美丽在一个美好的晴天，海是非常大的。在世界上，比土地有更多海。您是否知道海南岛？ 那非常好。我们能看海滩、树和海。我们可以游泳和参观很多美好的地方。

7.Computers are changing our life.You can do a lot of things with a computer.Such as, you can use a computer to write articles, watch video CDs, play games and do office work.But the most important use of a computer is to join the Internet.We don’t need to leave home to borrow books from a library or to do shopping in a supermarket.Computers help us live a more convenient life.计算机改变我们的生活。您能做很多事用计算机。例如，您能使用计算机写文章，手表录影CDs，戏剧比赛和完成办公室工作。但对计算机的最重要的用途是加入Internet.我们不需要离开家去从图书馆借用书或在超级市场做购物。计算机帮助我们居住更加方便的生活。

8.Summer is the great season for all sports in the open air.It is the season for football which is often called the national sport because of its popularity.I usually watch television and read the newspaper reports about the football results of the little leagues.During the summer I like to go to the beach often because it is very close to my home.I usually go there during the summer vacation to relax after many months in school in the city.I feel very comfortable with the familiar quiet life of the villagers.夏天是户外运动最好的季节.这是一个橄榄球的季节,橄榄球由于广受欢迎被称为全民运动.我常常看电视,看报纸,从报道中获得小联盟橄榄球赛的比赛结果.夏日里,我喜欢经常去海滩,因为那里离我家不远.在城里的学校呆了几个月后,暑假我常常去那里放松一下.此处有我很熟悉的村民们的宁静生活,这让我倍感舒适.9.I think smiling is as important as sunshine.Smiling is like sunshine because it can make people happy and have a good day.If you aren’t happy, you can smile, and then you will feel happy.Someone may say, “But I don’t feel happy.” Then I would say, “Please smile as you do when you are happy or play with your friends happily.You will really be happy again.”

Smiling can let you have more friends.So I say, smiling is like a flower.It will give you happiness.我认为微笑是一样重要的象阳光。微笑是象阳光，因为它可能使人愉快和有一个早晨好。如果您不是愉快的，您能微笑，您然后将感觉愉快。某人也许说，“但是我不感到愉快”。然后我会说，“请微笑，您，当您愉快地是愉快或戏剧与您的朋友。您真正地再将是愉快的”。微笑可能让您有更多朋友。如此我说，微笑是象花。它将给您幸福

10.My family are going to Hainan.It's a good seaside city.We are staying there for a week.We are going to the beach and going swimming in the sea.We're visiting Tianya Haijiao，Wanquan River and many other beautiful places.I think we'll have a good time there.国庆节来了，我有七天的假期。

我们一家去海南。那是一个美丽的海滨城市。我们在那里待上一个星期。我们去沙滩，还在海里游泳。我们游览“天涯海角”，菀泉河还有别的许多好地方。我想我们在那里会玩得很开心 11.I'm now living in a small house with my parents.It has three floors with five bedrooms, three bathrooms, two big dining rooms and two living rooms.When my friends come to visit me, I will have enough bedrooms for them.We'll have a good time.Besides that, we will have a swimming pool behind the house and a garden in front of the house.In the morning, my parents can do some exercise in the garden.The air must be very fresh.When we feel tired, we can have a swim in the swimming pool.Life will be easy for us.I'll study harder than before so that the dream can come true.我现在和我的父母生活在一个小房子。

它有三层,有五个卧室,三个卫生间,两个大的餐厅和两个客厅。当我的朋友来看望我,我将有足够的卧室。我们将有一个美好的时光。除此之外,我们将房子后面有一个游泳池和一个花园在房子的前面。在早上,我的父母在花园里可以做一些运动。空气一定很新鲜。当我们感到疲倦的时候,我们可以在游泳池里游泳。生活对我们来说会很容易。我会比以前更努力学习,梦想可以成真。

12.I am now 14 years old.Yesterday was my birthday.My parents had a birthday party.I invited my friends to attend.My mother got up very early in the morning, and began to cook.My father to help her cooking.They are very busy.All my friends arrived, my mother brought food and a cake.My father gave me new clothes and some books as my birthday gift.My friends sang birthday songs for me, gave me some presents.I have a wonderful birthday.我现在14岁。昨天是我的生日。我的父母有一个生日聚会。我邀请朋友们参加。在早上我的妈妈起得很早,开始做饭。我父亲帮她做饭。他们很忙。

我的所有朋友都到了以后,妈妈端上食物和一个蛋糕。爸爸送给我新衣服和书作为生日礼物。我的朋友为我唱生日歌,给了我一些礼物。我有一个美好的生日。

13.I have a busy and interesting summer vacation.I do my homework every day, so I finished my homework ten days before the new term.I also every day and my friends to play table tennis and basketball.I sometimes go to the movies, and my friends went to the park.I browse the Internet, read books and watch TV every evening.I help my parents clean the room and cooking.我有一个忙碌而有趣的暑假。我每天做我的作业,所以我做完作业前十天新学期。我也每天都和我的朋友打乒乓球和篮球。我有时去看电影,和我的朋友去了公园。我浏览互联网,阅读书籍,每天晚上看电视。我帮助我的父母打扫房间和做饭。

14.Hello, boys and girls!My name is lu.I'm 14 years old.My birthday is on November 7.I am a movie fan.I like action movies and science fiction movies.My favorite actor is Jackie chan.He is a great action actor.He has many movies.For example: “the 80 days around the world”, “baby plan andRush hour”.The movie is very exciting.I really like baby plans, because they are exciting.I like action movies very much 你好,男孩和女孩!我的名字是科陆。我14岁。我的生日是11月7日。我是一个电影迷。我喜欢动作电影和科幻电影。我最喜欢的演员是成龙。他是一个伟大的行动的演员。他有许多电影。

为例：《世界各地的80天》,《宝贝计划andRush小时》。这些电影非常令人兴奋。我真的很喜欢宝贝计划,因为它们是令人兴奋的。我非常喜欢动作片电影。

15.It is about half past four.It is time to exercise.The students on the playground.They are playing a football match.Atom is one of them.He is good at football.He in the school football team.Atom and said, I like to play football.It is one of my favorite sports.Panchen and hao-ling wang friend, he is a football fan.Ronaldo is his favourite player.它大约是4点半。是时候运动。学生们在操场上。他们是在玩一场足球比赛。凌动就是其中之一。他擅长足球。他在学校的足球队。凌动说,我喜欢踢足球。它是我最喜欢的运动。**和王浩凌动的朋友,他是一个足球迷。罗纳尔多是他最喜欢的球员。

16.Today is the first day of Chinese New Year.I am wearing new sweaters and shoes.Some people always put the gifts, smiling at everyone.They wear red clothes.You can play with fireworks, but don't play in the room.We can eat a lot of Chinese food, rice dumplings, dumplings.Today is a beautiful day.今天是中国新年的第一天。我穿着新毛衣和鞋子。一些人总是把礼物,对每个人微笑。他们穿着红色的衣服。

你可以玩烟花,但不要在房间里玩。我们可以吃很多中国菜,啊粽子、饺子.今天是一个美好的一天

17.There are 55 students in my class.We study together.We play together.We talk to each other.We help each other.Our class is like a big family.We are very happy.We have a lot of the teacher.They are very kind.They are always good for us.They make us very very hard study.有55名学生在我的班。我们一起研究。我们一起玩。我们相互交谈。我们互相帮助。我们班就像一个大家庭。我们非常高兴。

我们有很多老师。他们非常善良。他们总是对我们好。他们让我们非常非常努力学习。

18.piano and I good at it.So I want to become a piano player.Play the piano is very interesting.And you can learn something of music.Piano can make you like music.A lot of musician and singer are love playing piano.Become a piano play is a hard job.But I believe I can do it.钢琴,我擅长它。所以我想成为一个钢琴家。弹钢琴是非常有趣的。你可以学习一些音乐。钢琴能让你喜欢音乐。许多音乐家和歌手都喜欢弹钢琴。成为一个钢琴演奏是一个辛苦的工作。但是我相信我能做到。

19.Oh!My god.Last Sunday my toothbrush is broken.I can't brush your teeth.So I went shopping with my mother.There are so many toothbrush.Finally, we chose a blue one.I like it very much.So we bought it.My mom says it's good for my teeth.Then we went home.Can I brush my teeth.I'm so happy!哦!我的神。上星期天我的牙刷坏了，我不能刷牙。所以我和我的妈妈去购物.有这么多牙刷。最后,我们选择了一个蓝色的。我非常喜欢它。所以我们买了它。我妈妈说它对我的牙齿有好处。然后我们就回家了。我可以刷我的牙齿。我真快乐!20.We all have neighbors.Neighbors get along well with each other.My neighbour has a daughter.We are the same age, we study in the same school.In the evening we always do homework together.So we often help each other.我们都有邻居。邻居彼此相处得很好。我的邻居有一个女儿。我们是同样的年龄,我们在同一所学校学习。在晚上我们总是在一起做作业。所以我们经常互相帮助。

第三篇：英语政府官员职位中英文翻译

英语政府官员职位中英文翻译

英美虽都是讲英语国家，但同一政府部门的首长名称不同：英国国家元首是国王（King）或女王（Queen），而美国的国家元首是总统（President）。英国内阁的首脑为首相（Prime Minister），其他组成人有：

First Lord of the Treasury 第一财政大臣（首相兼任）

Secretary of State for Foreign Affairs 外交大臣

Lord President of the Council 枢密院大臣

Lord Chancellor 大法官

Chancellor of the Exchequer 财政大臣

Chancellor of the Duchy of Lancaster 兰开斯特公爵郡大臣

Lord Privy Seal and Leader of the House of Commons 掌皇大臣兼下院领袖

Minister of Defense 国防大臣

Secretary of state for Commonwealth Relations 联邦关系事务大臣

Secretary of State for the Colonies 殖民地事务大臣

Secretary of State for Scotland 苏格兰事务大臣

Minister of Labor and National Service 劳工大臣

Minister for Housing and Local Government 住房及地方政府事物大臣

Minister of Town and Country Planning 都市及乡村计划大臣

Minister of Health 卫生大臣

Minister of Education 教育大臣

President of the Board of Trade 贸易大臣

Minister of Agriculture and Fisheries 农业和渔业大臣

Minister of Pensions and National Insurance 年金及国民保险大臣 此外还有非内阁阁员的政府部门首长 ：

First Lord Of the Admiralty 海军大臣

Secretary of State for War 陆军大臣

Secretary of State for Air 空军大臣

Minister of Fuel and Power 燃料电力大臣

Minister of Transport 运输大臣

Minister of Supply 供应大臣

Minister of Economic Affairs 经济事务大臣

Minister of Food 粮食大臣

Minister of Civil Aviation 民航大臣

Minister of Works 工程大臣

Paymaster General 主计大臣

Labor secretary 劳工部长

Postmaster General 邮政大臣

Attorney — General 检查总长

Solicitor — General 副检查总长

Lord Advocate 苏格兰检察总长

美国总统以下设十个行政主管，分掌国政，形成一个内阁：

Secretary of State 国务卿

Secretary of the Treasury 财政部长

Secretary of Defense 国防部长

Attorney General 司法部长

Postmaster General 邮政管理局长

Interior Secretary 内政部长

Agriculture Secretary 农业部长

Commerce Secretary 商务部长

第四篇：中英文翻译

Fundamentals This chapter describes the fundamentals of today’s wireless communications.First a detailed description of the radio channel and its modeling are presented, followed by the introduction of the principle of OFDM multi-carrier transmission.In addition, a general overview of the spread spectrum technique, especially DS-CDMA, is given and examples of potential applications for OFDM and DS-CDMA are analyzed.This introduction is essential for a better understanding of the idea behind the combination of OFDM with the spread spectrum technique, which is briefly introduced in the last part of this chapter.1.1 Radio Channel Characteristics Understanding the characteristics of the communications medium is crucial for the appropriate selection of transmission system architecture, dimensioning of its components, and optimizing system parameters, especially since mobile radio channels are considered to be the most difficult channels, since they suffer from many imperfections like multipath fading, interference, Doppler shift, and shadowing.The choice of system components is totally different if, for instance, multipath propagation with long echoes dominates the radio propagation.Therefore, an accurate channel model describing the behavior of radio wave propagation in different environments such as mobile/fixed and indoor/outdoor is needed.This may allow one, through simulations, to estimate and validate the performance of a given transmission scheme in its several design phases.1.1.1 Understanding Radio Channels In mobile radio channels(see Figure 1-1), the transmitted signal suffers from different effects, which are characterized as follows: Multipath propagation occurs as a consequence of reflections, scattering, and diffraction of the transmitted electromagnetic wave at natural and man-made objects.Thus, at the receiver antenna, a multitude of waves arrives from many different directions with different delays, attenuations, and phases.The superposition of these waves results in amplitude and phase variations of the composite received signal.Doppler spread is caused by moving objects in the mobile radio channel.Changes in the phases and amplitudes of the arriving waves occur which lead to time-variant multipath propagation.Even small movements on the order of the wavelength may result in a totally different wave superposition.The varying signal strength due to time-variant multipath propagation is referred to as fast fading.Shadowing is caused by obstruction of the transmitted waves by, e.g., hills, buildings, walls, and trees, which results in more or less strong attenuation of the signal strength.Compared to fast fading, longer distances have to be covered to significantly change the shadowing constellation.The varying signal strength due to shadowing is called slow fading and can be described by a log-normal distribution [36].Path loss indicates how the mean signal power decays with distance between transmitter and receiver.In free space, the mean signal power decreases with the square of the distance between base station(BS)and terminal station(TS).In a mobile radio channel, where often no line of sight(LOS)path exists, signal power decreases with a power higher than two and is typically in the order of three to five.Variations of the received power due to shadowing and path loss can be efficiently counteracted by power control.In the following, the mobile radio channel is described with respect to its fast fading characteristic.1.1.2 Channel Modeling The mobile radio channel can be characterized by the time-variant channel impulse response h(τ , t)or by the time-variant channel transfer function H(f, t), which is the Fourier transform of h(τ , t).The channel impulse response represents the response of the channel at time t due to an impulse applied at time t − τ.The mobile radio channel is assumed to be a wide-sense stationary random process, i.e., the channel has a fading statistic that remains constant over short periods of time or small spatial distances.In environments with multipath propagation, the channel impulse response is composed of a large number of scattered impulses received over Np different paths，Where

and ap, fD,p, ϕp, and τp are the amplitude, the Doppler frequency, the phase, and the propagation delay, respectively, associated with path p, p = 0,..., Np − 1.The assigned channel transfer function is

The delays are measured relative to the first detectable path at the receiver.The Doppler Frequency

depends on the velocity v of the terminal station, the speed of light c, the carrier frequency fc, and the angle of incidence αp of a wave assigned to path p.A channel impulse response with corresponding channel transfer function is illustrated in Figure 1-2.The delay power density spectrum ρ(τ)that characterizes the frequency selectivity of the mobile radio channel gives the average power of the channel output as a function of the delay τ.The mean delay τ , the root mean square(RMS)delay spread τRMS and the maximum delay τmax are characteristic parameters of the delay power density spectrum.The mean delay is

Where

Figure 1-2 Time-variant channel impulse response and channel transfer function with frequency-selective fading is the power of path p.The RMS delay spread is defined as Similarly, the Doppler power density spectrum S(fD)can be defined that characterizes the time variance of the mobile radio channel and gives the average power of the channel output as a function of the Doppler frequency fD.The frequency dispersive properties of multipath channels are most commonly quantified by the maximum occurring Doppler frequency fDmax and the Doppler spread fDspread.The Doppler spread is the bandwidth of the Doppler power density spectrum and can take on values up to two times |fDmax|, i.e.，1.1.3Channel Fade Statistics The statistics of the fading process characterize the channel and are of importance for channel model parameter specifications.A simple and often used approach is obtained from the assumption that there is a large number of scatterers in the channel that contribute to the signal at the receiver side.The application of the central limit theorem leads to a complex-valued Gaussian process for the channel impulse response.In the absence of line of sight(LOS)or a dominant component, the process is zero-mean.The magnitude of the corresponding channel transfer function

is a random variable, for brevity denoted by a, with a Rayleigh distribution given by

Where

is the average power.The phase is uniformly distributed in the interval [0, 2π].In the case that the multipath channel contains a LOS or dominant component in addition to the randomly moving scatterers, the channel impulse response can no longer be modeled as zero-mean.Under the assumption of a complex-valued Gaussian process for the channel impulse response, the magnitude a of the channel transfer function has a Rice distribution given by

The Rice factor KRice is determined by the ratio of the power of the dominant path to thepower of the scattered paths.I0 is the zero-order modified Bessel function of first kind.The phase is uniformly distributed in the interval [0, 2π].1.1.4Inter-Symbol(ISI)and Inter-Channel Interference(ICI)The delay spread can cause inter-symbol interference(ISI)when adjacent data symbols overlap and interfere with each other due to different delays on different propagation paths.The number of interfering symbols in a single-carrier modulated system is given by

For high data rate applications with very short symbol duration Td < τmax, the effect of ISI and, with that, the receiver complexity can increase significantly.The effect of ISI can be counteracted by different measures such as time or frequency domain equalization.In spread spectrum systems, rake receivers with several arms are used to reduce the effect of ISI by exploiting the multipath diversity such that individual arms are adapted to different propagation paths.If the duration of the transmitted symbol is significantly larger than the maximum delay Td τmax, the channel produces a negligible amount of ISI.This effect is exploited with multi-carrier transmission where the duration per transmitted symbol increases with the number of sub-carriers Nc and, hence, the amount of ISI decreases.The number of interfering symbols in a multi-carrier modulated system is given by

Residual ISI can be eliminated by the use of a guard interval(see Section 1.2).The maximum Doppler spread in mobile radio applications using single-carrier modulation is typically much less than the distance between adjacent channels, such that the effect of interference on adjacent channels due to Doppler spread is not a problem for single-carrier modulated systems.For multi-carrier modulated systems, the sub-channel spacing Fs can become quite small, such that Doppler effects can cause significant ICI.As long as all sub-carriers are affected by a common Doppler shift fD, this Doppler shift can be compensated for in the receiver and ICI can be avoided.However, if Doppler spread in the order of several percent of the sub-carrier spacing occurs, ICI may degrade the system performance significantly.To avoid performance degradations due to ICI or more complex receivers with ICI equalization, the sub-carrier spacing Fs should be chosen as

such that the effects due to Doppler spread can be neglected(see Chapter 4).This approach corresponds with the philosophy of OFDM described in Section 1.2 and is followed in current OFDM-based wireless standards.Nevertheless, if a multi-carrier system design is chosen such that the Doppler spread is in the order of the sub-carrier spacing or higher, a rake receiver in the frequency domain can be used [22].With the frequency domain rake receiver each branch of the rake resolves a different Doppler frequency.1.1.5Examples of Discrete Multipath Channel Models Various discrete multipath channel models for indoor and outdoor cellular systems with different cell sizes have been specified.These channel models define the statistics of the 5 discrete propagation paths.An overview of widely used discrete multipath channel models is given in the following.COST 207 [8]: The COST 207 channel models specify four outdoor macro cell propagation scenarios by continuous, exponentially decreasing delay power density spectra.Implementations of these power density spectra by discrete taps are given by using up to 12 taps.Examples for settings with 6 taps are listed in Table 1-1.In this table for several propagation environments the corresponding path delay and power profiles are given.Hilly terrain causes the longest echoes.The classical Doppler spectrum with uniformly distributed angles of arrival of the paths can be used for all taps for simplicity.Optionally, different Doppler spectra are defined for the individual taps in [8].The COST 207 channel models are based on channel measurements with a bandwidth of 8–10 MHz in the 900-MHz band used for 2G systems such as GSM.COST 231 [9] and COST 259 [10]: These COST actions which are the continuation of COST 207 extend the channel characterization to DCS 1800, DECT, HIPERLAN and UMTS channels, taking into account macro, micro, and pico cell scenarios.Channel models with spatial resolution have been defined in COST 259.The spatial component is introduced by the definition of several clusters with local scatterers, which are located in a circle around the base station.Three types of channel models are defined.The macro cell type has cell sizes from 500 m up to 5000 m and a carrier frequency of 900 MHz or 1.8 GHz.The micro cell type is defined for cell sizes of about 300 m and a carrier frequency of 1.2 GHz or 5 GHz.The pico cell type represents an indoor channel model with cell sizes smaller than 100 m in industrial buildings and in the order of 10 m in an office.The carrier frequency is 2.5 GHz or 24 GHz.COST 273: The COST 273 action additionally takes multi-antenna channel models into account, which are not covered by the previous COST actions.CODIT [7]: These channel models define typical outdoor and indoor propagation scenarios for macro, micro, and pico cells.The fading characteristics of the various propagation environments are specified by the parameters of the Nakagami-m distribution.Every environment is defined in terms of a number of scatterers which can take on values up to 20.Some channel models consider also the angular distribution of the scatterers.They have been developed for the investigation of 3G system proposals.Macro cell channel type models have been developed for carrier frequencies around 900 MHz with 7 MHz bandwidth.The micro and pico cell channel type models have been developed for carrier frequencies between 1.8 GHz and 2 GHz.The bandwidths of the measurements are in the range of 10–100 MHz for macro cells and around 100 MHz for pico cells.JTC [28]: The JTC channel models define indoor and outdoor scenarios by specifying 3 to 10 discrete taps per scenario.The channel models are designed to be applicable for wideband digital mobile radio systems anticipated as candidates for the PCS(Personal Communications Systems)common air interface at carrier frequencies of about 2 GHz.UMTS/UTRA [18][44]: Test propagation scenarios have been defined for UMTS and UTRA system proposals which are developed for frequencies around 2 GHz.The modeling of the multipath propagation corresponds to that used by the COST 207 channel models.HIPERLAN/2 [33]: Five typical indoor propagation scenarios for wireless LANs in the 5 GHz frequency band have been defined.Each scenario is described by 18discrete taps of the delay power density spectrum.The time variance of the channel(Doppler spread)is modeled by a classical Jake’s spectrum with a maximum terminal speed of 3 m/h.Further channel models exist which are, for instance, given in [16].1.1.6Multi-Carrier Channel Modeling Multi-carrier systems can either be simulated in the time domain or, more computationally efficient, in the frequency domain.Preconditions for the frequency domain implementation are the absence of ISI and ICI, the frequency nonselective fading per sub-carrier, and the time-invariance during one OFDM symbol.A proper system design approximately fulfills these preconditions.The discrete channel transfer function adapted to multi-carrier signals results in

where the continuous channel transfer function H(f, t)is sampled in time at OFDM symbol rate s and in frequency at sub-carrier spacing Fs.The duration

s is the total OFDM symbol duration including the guard interval.Finally, a symbol transmitted onsub-channel n of the OFDM symbol i is multiplied by the resulting fading amplitude an,i and rotated by a random phase ϕn,i.The advantage of the frequency domain channel model is that the IFFT and FFT operation for OFDM and inverse OFDM can be avoided and the fading operation results in one complex-valued multiplication per sub-carrier.The discrete multipath channel models introduced in Section 1.1.5 can directly be applied to(1.16).A further simplification of the channel modeling for multi-carrier systems is given by using the so-called uncorrelated fading channel models.1.1.6.1Uncorrelated Fading Channel Models for Multi-Carrier Systems These channel models are based on the assumption that the fading on adjacent data symbols after inverse OFDM and de-interleaving can be considered as uncorrelated [29].This assumption holds when, e.g., a frequency and time interleaver with sufficient interleaving depth is applied.The fading amplitude an,i is chosen from a distribution p(a)according to the considered cell type and the random phase ϕn,I is uniformly distributed in the interval [0,2π].The resulting complex-valued channel fading coefficient is thus generated independently for each sub-carrier and OFDM symbol.For a propagation scenario in a macro cell without LOS, the fading amplitude an,i is generated by a Rayleigh distribution and the channel model is referred to as an uncorrelated Rayleigh fading channel.For smaller cells where often a dominant propagation component occurs, the fading amplitude is chosen from a Rice distribution.The advantages of the uncorrelated fading channel models for multi-carrier systems are their simple implementation in the frequency domain and the simple reproducibility of the simulation results.1.1.7Diversity The coherence bandwidth of a mobile radio channel is the bandwidth over which the signal propagation characteristics are correlated and it can be approximated by

The channel is frequency-selective if the signal bandwidth B is larger than the coherence bandwidth.On the other hand, if B is smaller than , the channel is frequency nonselective or flat.The coherence bandwidth of the channel is of importance for evaluating the performance of spreading and frequency interleaving techniques that try to exploit the inherent frequency diversity Df of the mobile radio channel.In the case of multi-carrier transmission, frequency diversity is exploited if the separation of sub-carriers transmitting the same information exceeds the coherence bandwidth.The maximum achievable frequency diversity Df is given by the ratio between the signal bandwidth B and the coherence bandwidth，The coherence time of the channel is the duration over which the channel characteristics can be considered as time-invariant and can be approximated by

If the duration of the transmitted symbol is larger than the coherence time, the channel is time-selective.On the other hand, if the symbol duration is smaller than , the channel is time nonselective during one symbol duration.The coherence time of the channel is of importance for evaluating the performance of coding and interleaving techniques that try to exploit the inherent time diversity DO of the mobile radio channel.Time diversity can be exploited if the separation between time slots carrying the same information exceeds the coherence time.A number of Ns successive time slots create a time frame of duration Tfr.The maximum time diversity Dt achievable in one time frame is given by the ratio between the duration of a time frame and the coherence time, A system exploiting frequency and time diversity can achieve the overall diversity

The system design should allow one to optimally exploit the available diversity DO.For instance, in systems with multi-carrier transmission the same information should be transmitted on different sub-carriers and in different time slots, achieving uncorrelated faded replicas of the information in both dimensions.Uncoded multi-carrier systems with flat fading per sub-channel and time-invariance during one symbol cannot exploit diversity and have a poor performance in time and frequency selective fading channels.Additional methods have to be applied to exploit diversity.One approach is the use of data spreading where each data symbol is spread by a spreading code of length L.This, in combination with interleaving, can achieve performance results which are given for

by the closed-form solution for the BER for diversity reception in Rayleigh fading channels according to [40]

Whererepresents the combinatory function，and σ2 is the variance of the noise.As soon as the interleaving is not perfect or the diversity offered by the channel is smaller than the spreading code length L, or MCCDMA with multiple access interference is applied,(1.22)is a lower bound.For L = 1, the performance of an OFDM system without forward error correction(FEC)is obtained, 9

which cannot exploit any diversity.The BER according to(1.22)of an OFDM(OFDMA, MC-TDMA)system and a multi-carrier spread spectrum(MC-SS)system with different spreading code lengths L is shown in Figure 1-3.No other diversity techniques are applied.QPSK modulation is used for symbol mapping.The mobile radio channel is modeled as uncorrelated Rayleigh fading channel(see Section 1.1.6).As these curves show, for large values of L, the performance of MC-SS systems approaches that of an AWGN channel.Another form of achieving diversity in OFDM systems is channel coding by FEC, where the information of each data bit is spread over several code bits.Additional to the diversity gain in fading channels, a coding gain can be obtained due to the selection of appropriate coding and decoding algorithms.中文翻译 1基本原理

这章描述今日的基本面的无线通信。第一一个的详细说明无线电频道，它的模型被介绍，跟随附近的的介绍的原则的参考正交频分复用多载波传输。此外，一个一般概观的扩频技术，尤其ds-cdma，被给，潜力的例子申请参考正交频分复用，DS对1。分配的通道传输功能是

有关的延误测量相对于第一个在接收器检测到的路径。多普勒频率

取决于终端站，光速c，载波频率fc的速度和发病路径分配给速度v波αp角度页具有相应通道传输信道冲激响应函数图1-2所示。

延迟功率密度谱ρ（τ）为特征的频率选择性移动无线电频道给出了作为通道的输出功能延迟τ平均功率。平均延迟τ，均方根（RMS）的时延扩展τRMS和最大延迟τmax都是延迟功率密度谱特征参数。平均时延特性参数为

有

图1-2时变信道冲激响应和通道传递函数频率选择性衰落是权力页的路径均方根时延扩展的定义为 同样，多普勒频谱的功率密度（FD）的特点可以定义

在移动时变无线信道，并给出了作为一种金融衍生工具功能的多普勒频率通道输出的平均功率。多径信道频率分散性能是最常见的量化发生的多普勒频率和多普勒fDmax蔓延fDspread最大。多普勒扩散是功率密度的多普勒频谱带宽，可价值观需要两年时间| fDmax|，即

1.1.3频道淡出统计

在衰落过程中的统计特征和重要的渠道是信道模型参数规格。一个简单而经常使用的方法是从假设有一个通道中的散射，有助于在大量接收端的信号。该中心极限定理的应用导致了复杂的值的高斯信道冲激响应过程。在对视线（LOS）或线的主要组成部分的情况下，这个过程是零的意思。相应的通道传递函数幅度

是一个随机变量，通过给定一个简短表示由瑞利分布，有

是的平均功率。相均匀分布在区间[0，2π]。

在案件的多通道包含洛杉矶的或主要组件除了随机移动散射，通道脉冲响应可以不再被建模为均值为零。根据信道脉冲响应的假设一个复杂的值高斯过程，其大小通道的传递函数A的水稻分布给出

赖斯因素KRice是由占主导地位的路径权力的威力比分散的路径。I0是零阶贝塞尔函数的第一阶段是一致kind.The在区间[0，2π]分发。

1.1.4符号间（ISI）和通道间干扰（ICI）

延迟的蔓延引起的符号间干扰（ISI）当相邻的数据符号上的重叠与互相不同的传播路径，由于不同的延迟干涉。符号的干扰在单载波调制系统的号码是给予

对于高数据符号持续时间很短运输署<蟿MAX时，ISI的影响，这样一来，速率应用，接收机的复杂性大大增加。对干扰影响，可以抵消，如时间或频域均衡不同的措施。在扩频系统，与几个臂Rake接收机用于减少通过利用多径分集等，个别武器适应不同的传播路径的干扰影响。

如果发送符号的持续时间明显高于大的最大延迟运输署蟿最大，渠道产生ISI的微不足道。这种效果是利用多载波传输的地方，每发送符号的增加与子载波数控数目，因此，ISI的金额减少的持续时间。符号的干扰多载波调制系统的号码是给予

可以消除符号间干扰由一个保护间隔（见1.2节）的使用。

最大多普勒在移动无线应用传播使用单载波调制通常比相邻通道，这样，干扰对由于多普勒传播相邻通道的作用不是一个单载波调制系统的问题距离。对于多载波调制系统，子通道间距FS可以变得非常小，这样可以造成严重的多普勒效应ICI的。只要所有子载波只要是一个共同的多普勒频移金融衍生工具的影响，这可以补偿多普勒频移在接收器和ICI是可以避免的。但是，如果在对多普勒子载波间隔为几个百分点的蔓延情况，卜内门可能会降低系统的性能显着。为了避免性能降级或因与ICI卜内门更复杂的接收机均衡，子载波间隔财政司司长应定为

这样说，由于多普勒效应可以忽略不扩散（见第4章）。这种方法对应于OFDM的1.2节中所述，是目前基于OFDM的无线标准遵循的理念。

不过，如果多载波系统的设计选择了这样的多普勒展宽在子载波间隔或更高，秩序是在频率RAKE接收机域名可以使用[22]。随着频域RAKE接收机每个支部耙解决了不同的多普勒频率。

1.1.5多径信道模型的离散的例子

各类离散多与不同的细胞大小的室内和室外蜂窝系统的信道模型已经被指定。这些通道模型定义的离散传播路径的统计信息。一种广泛使用的离散多径信道模型概述于下。造价207[8]：成本207信道模型指定连续四个室外宏蜂窝传播方案，指数下降延迟功率密度谱。这些频道功率密度的离散谱的实现都是通过使用多达12个频道。与6频道设置的示例列于表1-1。在这种传播环境的几个表中的相应路径延迟和电源配置给出。丘陵地形导致最长相呼应。

经典的多普勒频谱与均匀分布的到达角路径可以用于简化所有的频道。或者，不同的多普勒谱定义在[8]个人频道。207信道的成本模型是基于一个8-10兆赫的2G，如GSM系统中使用的900兆赫频段信道带宽的测量。造价231[9]和造价259[10]：这些费用是行动的延续成本207扩展通道特性到DCS1800的DECT，HIPERLAN和UMTS的渠道，同时考虑到宏观，微观和微微小区的情况为例。空间分辨率与已定义的通道模型在造价259。空间部分是介绍了与当地散射，这是在基站周围设几组圆的定义。三种类型的通道模型定义。宏细胞类型具有高达500〜5000米，载波频率为900兆赫或1.8 GHz的单元尺寸。微细胞类型被定义为细胞体积约300米，1.2 GHz或5 GHz载波频率。细胞类型代表的Pico与细胞体积小于100工业建筑物和办公室中的10 m阶米室内信道模型。载波频率为2.5 GHz或24千兆赫。造价273：成本273行动另外考虑到多天线信道模型，这是不是由先前的费用的行为包括在内。

CODIT [7]：这些通道模型定义的宏，微，微微蜂窝和室外和室内传播的典型案例。各种传播环境的衰落特性是指定的在NakagamiSS）的不同扩频码L是长度，如图1-3所示的系统。没有其他的分集技术被应用。QPSK调制用于符号映射。移动无线信道建模为不相关瑞利衰落信道（见1.1.6）。由于这些曲线显示，办法，AWGN信道的一对L时，对MC-SS系统性能有很大价值。

另一种实现形式的OFDM系统的多样性是由前向纠错信道编码，在这里，每个数据位的信息分散在几个代码位。附加在衰落信道分集增益，编码增益一个可因适当的编码和解码算法的选择。

第五篇：中英文翻译

蓄电池 battery 充电 converter 转换器 charger

开关电器 Switch electric 按钮开关 Button to switch 电源电器 Power electric 插头插座 Plug sockets