结构化训练的关键因素 [2]
论文作者:www.51lunwen.org论文属性:作业 Assignment登出时间:2016-05-04编辑:lily点击率:12036
论文字数:3237论文编号:org201605030852016406语种:英语 English地区:台湾价格:免费论文
关键词:塞浦路斯结构化训练电信服务
摘要:本文以作者在塞浦路斯电信局操作与维护服务部门实习的经历来阐述结构化训练的内容、意义及关键因素,通过分析工作情况,最终得出结论,试图给出比较有效的工作训练方法。
my division had to do with the technical part of the mobile systems in Cyprus. I was also introduced to some other departments during my weeks in the internship.
培训描述——TRAINING DESCRIPTION
As I was placed in the operation and maintenance department, my first task was to become acquainted with the structure of the GSM and the UMTS networks and the radio site equipment, which is mainly supplied in Cyprus by Ericsson for the GSM system and supplied by Siemens for the UMTS system. Besides the infield visits, where I got some instructions from my colleagues, I got the opportunity to work myself into the topic.
GSM is a cellular radio network, which means that mobile phones connect to it through cells found in their immediate vicinity. The network in Cyprus operates at 900 MHz or 1800 MHz bands. Each broadcasting band is divided into different frequency channels, with a distance between each channel of 200 kHz. Time division multiplexing is applied to create 8 full rate or 16 half rate speech channels per carrier frequency, also called the logical channels. With an 8 channel TDMA frame, a data rate of about 270 Kbit/s is reached. Each cell operates at a different frequency channel than that of its neighboring cells to avoid interference.
Ericsson's GSM network is divided into three major systems: the Switching System (SS), the Base Station System (BSS) and the Operation and Support System (OSS). The main part of the SS is the Mobile Services Switching Center (MSC), which performs the telephone switching functions of the system and controls the calls from its network or other telephone networks. So it is the physical interface between the core and the mobile net and is also responsible for the allocation of the mobile phone numbers. All radio-related functions are performed in the Base Station System. The BSS consists of the Base Station Controller (BSC) and the Radio Base Station (RBS). The BSC is a high capacity switch, which connects the MSC with several RBS's. Different cell configuration data are defined and controlled by the BSC. It handles the connection and the handover of calls to other cells and controls the radio frequency power levels in the different base stations. One BSC is able to handle up to about 85 base stations. The RBS includes all radio and transmission interface equipment which is needed on the radio site. One RBS can serve up to 3 cells. The Operation and Support System has been implemented by Ericsson in order to provide a centralized operation and maintenance for the cellular network. The operator is able to monitor and control the entire hardware as well as several functions of the network. Each technical fault in the network is detected by the OSS, so that the operator can support the operation and maintenance team with a detailed fault description.
Unlike the GSM network, the UMTS network in Cyprus uses a wideband spread-spectrum channel access method called W-CDMA, which operates with 2 carrier frequencies (at 2100 MHz) and supports, due to the asynchronous code division access, more mobile users at the same time. Furthermore it achieves higher data rates than the common GSM network, which reaches up to 21Mbit/s in theory. The data bursts of each mobile station are encoded with a unique spreading code. The information for each mobile station can be filtered out by the correlation of the interfered carrie
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