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1、蜂窝无线系统的研究,专业班级：通信工程,姓名：杨迪,学号：P01114073,安徽大学,题目 蜂窝无线通信系统的研究 学生姓名 杨迪 专业班级 通信工程 学 号P01114073 院 （系） 电子信息工程学院 指导教师（职称）杨洋,1,蜂窝无线系统的研究,专业班级：通信工程,姓名：杨迪,学号：P01114073,RESEARCH OF CELLULAR WIRELESS COMMUNATION SYSTEM 一：Conception AbstractCellular systems is also called the village system. Is all the areas cove
2、red by divided into several village, each district the radius of the visual user distribution density in 1 10 km or so. Set up a base station in every community service for users within the scope of this area. And through the district division to further improve the system capacity.This system by mo
3、bile services switching center (MSC), base station (BS) equipment and mobile station (MS) (the user equipment) and the exchange center to the base station of a transmission line, as shown in the figure below. At present in the operation of the 900 MHZ (TACS) first generation mobile communication sys
4、tem simulation system and the second generation mobile communication (GSM) digital system belong to this category.Is the movement of the mobile station exchange center and the public telephone network (PSTN) is what we usually call telephone network is linked together, between the mobile switching c
5、enter is responsible for the connection between the base station communication, call process, the mobile station (such as mobile phones) and subordinate to the base station to establish contact, by the base station connected to the mobile switching center again, finally access to the public telephon
6、e network. 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 transmissions received at the base stations from each mobile are trans
7、lated 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 to the base station, where they are transmitted to the mobile.
8、 Cellular systems employ either frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), or spatial,2,3,蜂窝无线系统的研究,专业班级：通信工程,姓名：杨迪,学号：P01114073,4,蜂窝无线系统的研究,专业班级：通信工程,姓名：杨迪,学号：P01114073,random events over time and space. These random events
9、, such as the 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
10、aforementioned 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
11、 the geographic 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 com
12、plexity of multiple 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
13、the instantaneous 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 the transient effects crea
14、ted by the channel. However, in order to determine the overall system performance of a large number of users spread over a wide geographic area, it is necessary to incorporate large-scale effects such as the statistical behavior of interference and signal levels experienced by individual users over
15、large distances, while ignoring the transient channel characteristics. One may think of link-level simulation as being a vernier adjustment on the performance of a communication system, and the system-level simulation as being a coarse, yet important, approximation of the overall level of quality th
16、at any user could expect at any time. Cellular systems achieve high capacity (e.g., serve a large number of users) by allowing the mobile stations to share, or reuse a communication channel in different regions of the geographic service area. Channel reuse leads to co-channel interference among users sharing the same channel, which is recognized as one of the major limiting,5,蜂窝无线系统的研究,专业班级：通信工程,姓名：杨迪,学号：P01114073,factors of performance and capacity of a cellular system. An appropriate understan
