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1、郑州轻工业学院郑州轻工业学院 本科毕业设计（论文）英文翻译题 目 蜂窝无线通信系统的研究蜂窝无线通信系统的研究学生姓名 耿永鹏 专业班级 信息工程 07-1 班 学 号 200707070111 院 （系） 计算机与通信工程学院 指导教师（职称） 张娜（讲师） 完成时间 2011 年 5 月 30 日 1英文原文RESEARCH OF CELLULAR WIRELESS COMMUNATION SYSTEMAbstractCellular communication systems allow a large number of mobile users to seamlessly and s
2、imultaneously communicate to wireless modems at fixed base stations using a limited amount of radio frequency (RF) spectrum. The RF transmissions received at the base stations from each mobile are translated to baseband, or to a wideband microwave link, and relayed to mobile switching centers (MSC),
3、 which connect the mobile transmissions with the Public Switched Telephone Network (PSTN). Similarly, communications from the PSTN are sent to the base station, where they are transmitted to the mobile. Cellular systems employ either frequency division multiple access (FDMA), time division multiple
4、access (TDMA), code division multiple access (CDMA), or spatial division multiple access (SDMA).1 IntroductionA wide variety of wireless communication systems have been developed to provide access to the communications infrastructure for mobile or fixed users in a myriad of operating environments. M
5、ost of todays wireless systems are based on the cellular radio concept. Cellular communication systems allow a large number of mobile users to seamlessly and simultaneously communicate to wireless modems at fixed base stations using a limited amount of radio frequency (RF) spectrum. The RF transmiss
6、ions received at the base stations from each mobile are translated to baseband, or to a wideband microwave link, and relayed to mobile switching centers (MSC), which connect the mobile transmissions with the Public Switched Telephone Network (PSTN). Similarly, communications from the PSTN are sent t
7、o the base station, where they are transmitted to the mobile. Cellular systems employ either frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), or spatial division multiple access (SDMA) .Wireless communication links experience host
8、ile physical channel characteristics, such as time-varying multipath and shadowing due to large objects in the propagation path. 2In addition, the performance of wireless cellular systems tends to be limited by interference from other users, and for that reason, it is important to have accurate tech
9、niques for modeling interference. These complex channel conditions are difficult to describe with a simple analytical model, although several models do provide analytical tractability with reasonable agreement to measured channel data . However, even when the channel is modeled in an analytically el
10、egant manner, in the vast majority of situations it is still difficult or impossible to construct analytical solutions for link performance when error control coding, equalization, diversity, and network models are factored into the link model. Simulation approaches, therefore, are usually required
11、when analyzing the performance of cellular communication links.Like wireless links, the system performance of a cellular radio system is most effectively modeled using simulation, due to the difficulty in modeling a large number of random events over time and space. These random events, such as the
12、location of users, the number of simultaneous users in the system, the propagation conditions, interference and power level settings of each user, and the traffic demands of each user,combine together to impact the overall performance seen by a typical user in the cellular system. The aforementioned
13、 variables are just a small sampling of the many key physical mechanisms that dictate the instantaneous performance of a particular user at any time within the system. The term cellular radio system,therefore, refers to the entire population of mobile users and base stations throughout the geographi
14、c service area, as opposed to a single link that connects a single mobile user to a single base station. To design for a particular system-level performance, such as the likelihood of a particular user having acceptable service throughout the system, it is necessary to consider the complexity of mul
15、tiple users that are simultaneously using the system throughout the coverage area. Thus, simulation is needed to consider the multi-user effects upon any of the individual links between the mobile and the base station.The link performance is a small-scale phenomenon, which deals with the instantaneo
16、us changes in the channel over a small local area, or small time duration, over which the average received power is assumed constant . Such assumptions are sensible in the design of error control codes, equalizers, and other components that serve to mitigate 3the transient effects created by the channel. However, in order to determine the overall sy
