网络技术外文翻译

外文资料翻译 Discussion on the Development Trend of Mobile Communications I Introduction Mobile communication means between the mobile users or mobile users and fixed communications between With the development of electronic technology particularly semiconductors sets Development of circuit and computer technology and mobile communications have enjoyed rapid development With the expansion of its application fields and on improving the performance requirements allow mobile communication in technology and development of the theory to a higher level Since in the 1980s of the 20th century the mobile communications have become indispensable in modern communication network and one of the fastest means of communication Reviewing the development of mobile communications mobile communications development through several stages of development the first major cellular mobile communication technology of analog mobile communications the technical characteristics of Cellular network structure overcome the regional capacity low restricted the scope of activities of the problem Second G is the cellular mobile communications cellular systems can provide integrated service digital transmission and other advantages Main Characteristics of third G is in addition to providing second of mobile communication system own advantages overcome its shortcomings but can also provide broadband multimedia service can provide high quality video multimedia integrated services and global roaming With most of them are now second technology third technology is still not very successful but there are already fourth technology vision 4G standard with more than third of the fourth mobile communication system function II 4G about mobile communication fourth the concept of mobile communication technologies as broadband access and distribution network with asymmetry over 2Mbits data transmission capacity It consists of fixed broadband wireless access and broadband wireless local area network mobile broadband system and interactive broadcasting network fourth G standards than third standard has more functionality In different fixed fourth g wireless platforms and wireless services across different frequency band network in any place with broadband Internet access including satellite communication and stratospheric communication to provide orientation of time data acquisition and remote control comprehensive functions In addition fourth mobile communication systems are integrated broadband mobile communication system of multifunctional are broadband IP system Currently in development and research of 4G communications will have the following characteristics A communications faster The initial study on 4G communications is aimed at enhancing cellular phones and other wireless access the Internet mobile device rate so 4G characteristics of communication is it a faster speed of wireless communication Experts estimated that fourth mobile communications system up to 10 20Mbits maximum reach 100Mbits B network spectrum width To make 4G communication transmission speed of up to 100 Mbits operators must be on the basis of 3G communications network to carry out large scale improvement so 4G network on communication bandwidth than 3G network bandwidth much higher According to the study each 4G channel will hold the 100 MHz spectrum equal to 20 times of the W CDMA3G network C Complete integration of the three services Personal communications information systems broadcasting and entertainment businesses such as seamless connection as a whole meet the various needs of users 4G should be able to integrate different models of wireless communication to from indoor wireless local area network and Bluetooth network cellular signal and radio and television to satellite communication mobile users to roam freely from a standard to another standard Business applications interconnection between various system platform more convenient safe and for different users more personalized 4G mobile phone from the point of view of the appearance and style will have more breakthroughs can think of is spectacles and watches cosmetic boxes sneakers are likely to become 4G terminal D intelligent properties of even higher Fourth Mobile Intelligent better not only expressed in the design and operation of 4G communication terminal with intelligent but more importantly 4G function of cell phone can implement many unimaginable For example 4G mobile phones will be based on the environment time and other factors to timely to remind the owner of the cell phone III 4G access system in mobile communications 4G system for mobile communication access remarkable feature is that intelligent multi mode terminals multi modeterminal based on common platform through a variety of technology in various network system platform realization of seamless connection and collaboration In 4G mobile communications based on a common platform for all kinds of special access system mutual cooperation in the most optimal manner to meet the communication needs of different users When terminal access multi model systems network adaptive allocation band give the optimization of routing in order to achieve the best effect of communications With the development of technology and changes in market demand new technology will constantly emerging Different types of access technology designed for different business therefore the basis of our access application fields of technology small mobile radius and working environment and to access technology for layers Distribution layer mainly by the stratospheric communications satellite communication and broadcasting and TV communication and the scope of service coverage Cellular layer mainly by 2G 3G communication systems services covering larger Hot cell layer is mainly composed of WLAN network services to focus on the campus communities meeting center mobile communication ability is very limited Personal network layer mainly used in the home Office and other places the service scope of coverage is very small Mobile Communications Limited ability but through Internet access systems of other network layer Fixed Network Double strands coaxial cable fiber composition of fixed communication system Network access system in a very important position in the entire mobile networks To improve network performance access system of high level agreements and Research Network self optimization and automatic reconfiguration technology and dynamic spectrum allocation and resource allocation technology network management and cooperation between different access system Improving and extending the application of IP technology in mobile network strengthening the software radio technology and optimization of radio transmission technologies such as supporting real time and non real time business seamless connectivity and network security IV 4G key technology of mobile communication system A positioning technology Positioning mobile terminal location method for measuring and calculating methods It is mainly based on mobile terminal location location based on mobile network location or mixed three ways 4G mobile communication systems mobile terminal in mobile communication between different system platforms therefore for mobile terminal location and tracking is the realization of mobile terminal in seamless connections between different system platforms and systems prerequisite of high speed and high quality mobile communications and protection Switch technology for mobile terminal in different mobile community between communication between different frequencies or signal to reduce channel selection and so on Switch Technology is the future of mobile terminal in many of the communication system mobile community between solid foundation and an important technology in mobile communications It is mainly soft switching and hard handoff 4G communication system switching technique is more extensive scope and in soft switching and combination of hard handoff direction of development Three software radio technology 4G mobile communication systems software will become very complicated To this end The experts suggested the introduction of software radio technology as the mobile communications to third from second and fourth bridges in mobile communications Software radio technology to close as possible to the process of digital analog signal antenna AD and DA converter soon as possible to RF Front End using DSP channel separation modulation and demodulation and channel decoding and so on It aims to establish a communication platform platform software system to realize multi channel multi level and multi mode wireless communications Therefore the application of software radio technology mobile terminals can be achieved between the different systems and platforms unimpeded There are more mature software radio technology parameter control software radio systems Smart Antenna with inhibition of signal interference and automatic tracking and intelligence features such as digital beam adjustment can meet the data center mobile IP network performance requirements Smart Antenna beam in the space field suppression of mutual interference and to enhance the special scope of signal this technology can improve the quality of signal increase transmission capacity Five mutual Interference suppression and multiuser detection Development of interactive Interference suppression and multiuser detection technology should become part of the 4G they use interactive Interference suppression method introduction to the base stations and mobile phone system elimination of unnecessary nearby and co channel user interaction interference to ensure the high quality of receiver signal reception This combination will meet the needs of more user capacity but also can increase the coverage Mutual Interference suppression and multiuser detection combination of two technology will significantly reduce the deployment of network infrastructure ensure the improvement of service quality Signal Transmission and modulation of six new technology High speed mobile communications will face severe frequency selection fading frequency selectivefading To improve the signal performance research and development of intelligent modulation and demodulation techniques to effectively curb the decline For example the Orthogonal Frequency Division Multiplexing OFDM adaptive equalizer meanwhile the TPC Rake Spread Spectrum receive hopping FEC such as AQR and Turbo coding technology to get a better signal noise ratio of energy V Conclusions Now people 4G communication of the future looks very mysterious Many people think that the fourth wireless