专业英语作业移动通信的发展史Word文档下载推荐.docx

1、键入公司名称键入文档标题键入文档副标题Administrator2016/6/21 Tuesday This article mainly introduces the history of the development of mobile communication. Combined with the first generation, second generation, the third generation, the core technology of the fourth generation mobile communication of each generation c

2、ommunication technology advantages and disadvantages were introduced, to everyone of every generation mobile communication is what, and their production and development have a system of understanding.Introduction of The Development of Mobile CommunicationAbstract：This article mainly introduces the h

3、istory of the development of mobile communication. Combined with the first generation, second generation, the third generation, the core technology of the fourth generation mobile communication of each generation communication technology advantages and disadvantages were introduced, to everyone of e

4、very generation mobile communication is what, and their production and development have a system of understanding.Key words ：mobile;communication;developmentIntroduction:Mobile communication refers to the communication and exchange of information between the two parties at least one side in the mobi

5、le environment, which includes the communication between the two sides of the communication and the mobile object and the fixed point in the mobile environment. Mobile communication is part of an integral part of modern communication systems, mobile communication appeared to break the fixed relation

6、ship between communication and place. It uses wireless technology to solve the Internet cant solve the mobility, so that people in the mobile information acquisition and interactive. Its development and popularization has changed the society, but also changed the way of life of mankind, so that peop

7、le understand the era of high-speed information of the atmosphere. Modern mobile communication technology originated in the twenties of the 20th century, the mid seventies of the 20th century, it ushered in the rapid development of mobile communication, until now the OFDM Technology in the fourth ge

8、neration communication application and the development of mobile communication with each passing day. 1.The first generation of mobile communication system （1 g）First generation （1g） is the generation of moving communication system, simulation of cellular mobile communication systems, the use of ana

9、log modulation and multiple access technique is frequency division multiple access （FDMA）, the modulation is a frequency modulation （FM）, the main bearing voice service. The first generation mobile communication to the United States of Americas AMPS system and the European TACS as the representative

10、, our country in the late 80s, introduced the TACS technology, and built the first public mobile communication network in China. Due to different countries adopt different standard, different band and channel bandwidth, roaming user is not convenient, making the first generation of mobile communicat

11、ion system just a regional mobile communication system, in addition, in use process, analog cellular mobile communication system exposed a lot of problems, such as spectral efficiency low, single type of business and the call interrupt rate is high, communication equipment, heavy, but the the main p

12、roblem is the band resource and communication capacity and growing of mobile communication users of large capacity, multi service and high quality service of mobile communication demand contradiction have become increasingly prominent. Demand to promote the development. At this time the emergence of

13、 digital signal, allows people to see, the transmission of digital signals can be a transmission of the analog signal and digital signal than that of analog signals have more superior performance, strong confidentiality, error prone to restore and digital communication than analog communication have

14、 more kinds of business. Make people look from analog communication to digital communication. 2.The second generation of mobile communication systems （2 g）2G（Second Generation） The second generation mobile communication system, it has two kinds of multiple access methods, one kind is time division m

15、ultiple access （TDMA）, multiple access （CDMA） is a kind of code points. Representatives of TDMA IS the European GSM system, the representative of the CDMA IS the IS - 95 system of the United States. GSM standard system more perfect, the technology is relatively mature. Compared with the first genera

16、tion of mobile communication system, the second generation mobile communication system, the frequency and time used in combination to addressing, improve the utilization rate of the spectrum, can provide greater capacity; Anti-interference and antifading ability enhancement, can guarantee good voice quality. The confidentiality of the system is better; But the low speed of data transmission, data business develo