中英论文翻译-对照全球移动通信系统本科学位论文

1、GSM ( Global System for Mobile Communication)The success of mobile systems across the world is a sign that communication is moving towards a more personalized, convenient system. People who have to use a mobile phone on business soon begin to realize that the ability to phone any time, any place in

2、ones personal life rapidly becomes a necessity, not a convenience.The speed and rapidity with which the personal communications revolution takes place is, unlike fixed transmission systems, highly dependent on technology and communication standards.For mobile the three key elements to achieving serv

3、ice take-up are the cost, the size and the weight of the phone, and the cost and quality of the link.3 If any of these are wrong, especially the first two, then market growth is liable to be severely restricted. The fixed telephone service is global and the interconnection varies from coaxial cable

4、to optical fibre and satellite.The national standards are different, but with common interfaces and interface conversion, interconnection can take place. For mobile the problem is far more complex, with the need to roam creating a need for complex networks and systems. Thus in mobile the question of

5、 standardsis far more crucial to successthan fixed systems. 4 In addition, there is also the vexed question of spectrum allocation in the mobile area.Mobile systems originally operated in analog mode in the 450 MHz band, moving later to 900 MHz with digital GSM and then to 1,800 MHz with personal co

6、mmunication systems. The history of mobility can split into generations. The first generation systems were the advanced mobile phone systems (AMPS) in the US, total access communication system (TACS) in most of Europe and Nordic mobile telephone system (NMT); which were all analogue systems. The sec

7、ond generation is vary much dominated by the standard first set out in Europe by the group special mobile (GSM) committee, which was designed as a global mobile communication system.The GSM system is based on a cellular communications principle which was first proposed as a concept in the 1940s by B

8、ell System engineers in the US. The idea came out of the need to increase network capacity and got round the fact that broadcast mobile networks, operating in densely populated areas, could be jammed by a very small number of simultaneous calls. 5 The power of the cellular system was that it allowed

9、 frequency reuse.The cellular concept is defined by two features, frequency reuse and cell splitting. Frequency reuse comes into play by using radio channels on the same frequency in coverage areas that are far enough apart not to cause co-channel interference. This allows handling of simultaneous c

10、alls that exceed the theoretical spectral capacity. Cell splitting is necessarywhen the traffic demand on a cell has reached the maximum and the cell is then divided into a micro-cellular system. The shape of cell in a cellular system is always depicted as a hexagon and the cluster size can be seven

11、, nine or twelve.The GSM system requires a number of functions to be created for a fully operational mobile system.The cell coverage area is controlled by a base station which is itself made up of two elements. The first element is the transmission system which communicates out to the mobile and als

12、o receives information from it to set up and maintain calls when actually in operation. The base station transceiver (BST) is controlled by the base station controller (BSC), which communicates with the mobile switching center (MSC) the essential link to the local public switched telephone network (

13、PSTN),and to the subscriber data which is stored in registers within the system. The subscriber registers allow the GSM system to check a subscriber who requests the use of the network, allow access and then set up the charging function, etc. 6The GSM system was allocated part of the 900 MHz band at

14、 the 1978 World Administration Conference (WAC), the actual bands being 890 to 915 MHz for the uplink transmission and 935 to 960 MHz for the downlink. The access method is time division multiple access (TDMA).The GSM system operates in a burst transmission mode with 124 radio channels in the 900 MH

15、z band, and these bursts can carry different types of information. The first type of information is speech, which is coded at 6.5 kbit/s or 13 kbit/s. The second type is data, which can be sent at 3.6 kbit/s, 6 kbit/s or 12.6kbit/s. These two forms of transmission are the useful parts of the transmi

16、ssion, but have to be supported by overhead information which is sent in control channels (CCH).The use of digital radio transmission and the advanced handover algorithms between radio cells in GSM network allows for significantly better frequency usage than in analogue cellular systems, thus increa

17、sing the number of subscribers that can be served. 7 Since8 GSM provides common standard, cellular subscribers will also be able to use their telephones over the entire GSM service area. Roaming is fully automatic between and within all countries covered by GSM system. In addition to international r

18、oaming, GSM provides new services, such as high-speed data communication, Facsimile and short message service. The GSM technical specifications are designed to work in concert with other standards, e. g. ISDN. Interworking between the standards is in this way assured. In the long term perspective ce

19、llular systems, using a digital technology, will become the universal method of telecommunication.The third generation mobile communication system currently being developed9 in Europe is intended to integrate all the different services of second generation systems and cover a much wider range of bro

20、adband services (voice, data, video and multimedia) consistent and compatible with technology developments taking place within the fixed telecommunication networks.全球移动通信系统世界范围移动通信的成功标志着通信正在向着更加个人化、更加方便的通 信系统迈进。在商务中需使用移动电话的人们很快就认识到在个人生活中随时随 地打电话不仅仅带来了方便，而且是一种必需。不像固定通信系统，个人通信的快速发展在很大程度上依赖于技术和通信 标准的发展

21、。移动通信取得业务腾飞的三个关键因素是费用、手机的大小和重量以及链 路的收费和质量。 如果其中任何一个不能令人满意， 尤其是前两项， 移动通信的 市场增长就有可能受到严重的限制。固定电话业务是全球性的，系统的相互连接采取同轴电缆、光纤甚至卫星。 虽然各国标准不同， 但却采用共同的接口和接口转换装置， 使得相互连接可以进 行。对移动通信来说， 问题要更加复杂， 这是由于需要漫游业务就要有更复杂的 网络系统。 这样比起固定通信系统， 移动通信的标准问题是取得成功更为关键的 因素。此外，在移动通信领域，频谱的分配也是令人苦恼的问题。移动通信系统最初以模拟方式工作 (现在仍在运行 )，其频带在 450

22、 MHz ，后 来逐步发展到 900 MHz 的数字 GSM 系统，下一步是向工作在 1 800 MHz 的个人 通信系统发展。 移动通信的发展可分为几代。 第一代系统如美国的高级移动电话 系统(AMPS)、欧洲多数国家的全接入通信系统(TACS)以及北欧的移动电话系统 (NMT)，这些都是模拟系统。第二代移动通信系统在很大程度上是由欧洲特别移 动小组 (GS M )委员会所制订的标准决定的， 设计这一系统作为一种全球移动通信 系统。GSM 系统基于蜂窝通信系统原则。 这一概念是由美国贝尔系统工程师在 40 年代首先提出来的。 这一思想出自于增加网络容量的需要以及解决网络堵塞的问 题。在人口稠

23、密地区运行的广播式移动网络系统会由于很少的几个用户同时呼叫 而引起堵塞。蜂窝系统的威力在于允许频率的再利用。蜂窝概念由两个特点确定，即频率重复利用和小区分割。在相邻覆盖区域 相隔足够远而不至于引起共用信道干扰的， 通过使用同一频率的无线信道、 频率 再利用才起作用。 这样可以处理同时出现的呼叫并超过了理论频谱容量。 当小区的业务需求增到最大时， 就要进行小区划区，小区再被分成更小的蜂窝系统区域。 蜂窝系统的小区形状常被描绘成六边形，一群六边形小区的数量可以是 7 个、9 个或 12 个。对于一个充分运营的移动系统来说， GSM 系统需要建立一些功能。 小区的覆盖面由一个基站控制，基站本身由两个单元组成。第一个单元是 传输系统， 它在实际运行中与移动台进行通信以建立并保持通话。 第二个是基站 收发信机（B