外文翻译---通用移动通信系统的回顾

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1、附录 4 *大学 本科毕业设计（论文）外文翻译 课题名称： 基于 MATLAB 的 TD-SCDMA 通信系统的调制与解调仿真程序设计 学院（系）： 信息科学与工程学院 年级专业： *级通信工程 3 班 学生姓名： 指导教师： 完成日期： 20*年 3 月 26 日 附录 4 Review of UMTS 1.1 UMTS Network Architecture The European/Japanese 3G standard is referred to as UMTS. UMTS is one of a number of standards ratified by the ITU-T

2、 under the umbrella of IMT-2000. It is currently the dominant standard, with the US CDMA2000 standard gaining ground, particularly with operators that have deployed cdmaOne as their 2G technology. At time of writing,Japan is the most advanced in terms of 3G network deployment. The three incumbent op

3、erators there have implemented three different technologies: J-Phone is using UMTS,KDDI has a CDMA2000 network, and the largest operator NTT DoCoMo is using a system branded as FOMA (Freedom of Multimedia Access). FOMA is based on the original UMTS proposal, prior to its harmonization and standardiz

4、ation. The UMTS standard is specified as a migration from the second generation GSM standard to UMTS via the General Packet Radio System (GPRS) and Enhanced Data for Global Evolution (EDGE), as shown in Figure. This is a sound rationale since as of April 2003, there were over 847 Million GSM subscri

5、bers worldwide1, accounting for 68% of the global cellular subscriber figures. The emphasis is on keeping as much ofthe GSM network as possible to operate with the new system. We are now well on the road towards Third Generation (3G), where the network will support all traffic types: voice, video an

6、d data, and we should see an eventual explosion in the services available on the mobile device. The driving technology for this is the IP protocol. Many cellular operators are now at a position referred to as 2.5G, with the deployment of GPRS, which introduces an IP backbone into the mobile core net

7、work.The diagram below, Figure 2, shows an overview of the key components in a GPRS network, and how it fits into the existing GSM infrastructure. The interface between the SGSN and GGSN is known as the Gn interface 附录 4 and uses the GPRS tunneling protocol (GTP, discussed later). The primary reason

8、 for the introduction of this infrastructure is to offer connections to external packet networks, such as the Internet or a corporate Intranet. This brings the IP protocol into the network as a transport between the SGSN and GGSN. This allows data services such as email or web browsing on the mobile

9、 device,with users being charged based on volume of data rather than time connected. The dominant standard for delivery of 3G networks and services is the Universal Mobile Telecommunications System, or UMTS. The first deployment of UMTS is the Release 99 architecture, shown below in Figure 3. In thi

10、s network, the major change is in the radio access network (RAN) with the introduction of CDMA technology for the air interface, and ATM as a transport in the transmission part. These changes have been introduced principally to support the transport of voice, video and data services on the same netw

11、ork. The core network remains relatively unchanged, with primarily software upgrades. However, the IP protocol pushes further into the network with the RNC now communicating with the 3G SGSN using IP. The next evolution step is the Release 4 architecture, Figure 4. Here, the GSM core is replaced wit

12、h an IP network infrastructure based around Voice over IP technology. The MSC evolves into two separate components: a Media Gateway (MGW) and an MSC Server (MSS). This essentially breaks apart the roles of connection and connection control. An MSS can handle multiple MGWs, making the network more sc

13、aleable. Since there are now a number of IP clouds in the 3G network, it makes sense to merge these together into one IP or IP/ATM backbone (it is likely both options will be available to operators.) This extends IP right across the whole network, all the way to the BTS.This is referred to as the All-IP network, or the Release 5 architecture, as shown in Figure 5. The HLR/VLR/EIR are generalised and referred to as the HLR Subsystem(HSS).