《通信专业毕业设计论文外文翻译中英文对照WPF概述.doc》由会员分享，可在线阅读，更多相关《通信专业毕业设计论文外文翻译中英文对照WPF概述.doc（16页珍藏版）》请在三一文库上搜索。
1、通信专业 毕业设计论文 外文翻译中英文对照：WPF概述 理工学院毕业设计外文资料翻译 专 业: 姓 名: 学 号: 外文出处: Matthew.Pro WPF in C# 2010 Apress.2010 附 件: 1.外文资料翻译译文;2.外文原文。 指导教师评语:签名:年月日 附件1:外文资料翻译译文WPF概述 蜂窝无线电通信行业在过去十年中目睹了全球拥有了超过四十亿无线用户这一巨大发展,第一代(1G)模拟蜂窝系统只支持有限的漫游语音通信,而第二代(2G)数字系统比第一代有更高的容量和更好的语音质量。此外,由于在各个国家特别是在欧洲国家对漫游有相同的标准和共同的频谱分配,因此使之变得更为普
2、遍。在第二代(2G)蜂窝系统中,有两个是比较广泛部署的,他们分别是GSM(全球移动通信系统)和CDMA(码分多址)。相比于1G的模拟系统,2G系统主要支持语音通信。在后来发布2G版本的标准中,主要介绍了其支持数据传输的能力。然而,2G的数据传输速率普遍低于拨号连接支持,因此有了3G系统的出现,而ITU-R倡议的IMT-2000(国际移动电信2000年)为向3G的演进铺平了道路。根据IMT-2000的倡议,相关部门发表了一系列要求,如2 Mb / s的峰值数据率和车辆的流动性支持。GSM和CDMA形成了自己独立的3G合作伙伴项目(3GPP和3GPP2),使IMT-2000标准发展成基于CDMA技
3、术的标准。3GPP的3G标准被称为宽带CDMA(WCDMA),因为它使用了相比3GPP2的CDMA2000系统中1.25兆赫带宽来说更大的5兆赫带宽。3GPP2还制定了一个5兆赫兹的版本,支持三个1.25兆赫到副载波,其被称为CDMA2000-3X。为了分化从5兆赫兹的CDMA2000-3X的标准,1.25 兆赫兹的系统被称为CDMA2000-1X或者干脆称为3G-1X。 首次发布的3G标准并没有履行其所说的承诺,使高速数据传输的数据在实践中的支持率远远低于当时声称的标准。因此其需要作出一系列认真努力来提高有效地数据来支持3G系统。3GPP2中首先介绍了HRPD系统(高速率分组数据)系统使用的
4、数据流量,如通道敏感的调度,快速链路自适应和混合ARQ等HRPD系统。系统优化的各种先进技术,需要一个独立的1.25 兆赫兹载波和只支持没有语音的服务。正因为如此,HRPD系统最初被称为CDMA2000-1xEVDO(演进数据)系统。3GPP沿袭一种与之类似路径,并介绍HSPA(高速分组接入)技术提高对WCDMA系统的访问。HSPA的标准重复使用许多相同的数据优化技术为HRPD系统。然而,一个相对于HRPD系统来说的的差异是,在HSPA上相同的两个5 MHz载波可以同时进行语音和数据传输。平行于HRPD系统,3GPP2同时也制定了一个联合的语音数据标准,被称为CDMA2000-1xEVDV(演
5、进数据语音)。像HSPA一样,CDMA2000-1xEVDV系统支持同一载波上语音和数据,但是它从不商业化。在以后公布的HRPD,VoIP(互联网协议语音),介绍了其提供语音和数据服务在同一载体的能力。现在,两个3G标准,即HSPA和HRPD系统终于能够实现3G的承诺,并已被广泛部署在主要的蜂窝市场提供无线数据接入。1.1超越3G系统 当HSPA HRPD系统得到了开发和部署,IEEE 802 LMSC(局域网/城域网标准委员会)也推出了IEEE 802.16e移动宽带无线接入的标准。这个标准作为一种增强被引入到一个较早的IEEE802.16的标准固定宽带无线接入中去。以802.16e标准命名
6、的OFDMA(正交频分多址接入)采用不同的接入技术,并声称比HSPA和HRPD系统提供、更好的数据传输速率和频谱效率。IEEE 802.16系列标准被正式称为IEEE无线都会网路,它被称为名为Wi论坛的一个产业群的Wi(全球微波接入互操作性)。Wi论坛的使命是促进和认证宽带无线接入产品的兼容性和互操作性。支持在IEEE 802.16e标准的移动Wi系统被称为移动Wi。除了无线电技术的优势,移动Wi还雇用了一个简单的基于IP协议的网络架构。 引入移动Wi,3GPP和3GPP2超越基于OFDMA技术和网络架构,在类似的移动Wi的3G系统上开发自己的版本。在3GPP的3G系统之外,也被叫做进化的通用
7、无线电台访问(进化UTRA),也被广泛称为LTE(长期演进),或被称为3GPP2版本的UMB(超移动宽带)如图1.1。应当指出的是,这三个3G系统即超越移动Wi,LET,IMT-2000要求的UMB满足,因此它们可以满足IMT-2000标准。图1.1 蜂窝系统演化。 表1.1 LTE系统的属性。 1.2长期演进(LTE) LTE的目标是提供一个高数据速率,低延迟技术支持和分组优化的无线接入技术,并支持灵活的带宽部署。与此同时,新的网络架构的设计目标是,支持与分组交换通信的无缝移动性,优质的服务服和最低限度的延迟。 空中接口相关的属性总结在表1.1 中。系统支持灵活的带宽OFDMA和SC-FDM
8、A的访问,此外,FDD(频分双工)和TDD(时分双工),半双工FDD支持低成本的UE。不像软驱,它在半双工FDD在同一时间内操作的问题上是不需要发送和接收的,这样就避免了为UE而需要的昂贵的双工器。该系统主要是优化低转速可达15公里/小时。然而,系统规范允许一些性能下降超过350公里/ 小时的流动性支持。基于单载波频分多址的接入(SC-FDMA),由于低峰均值功率比(PAPR)相对的OFDMA上行接入,因此要增加上行覆盖。 该系统支持44 MIMO(多输入多输出)在20 MHz带宽326 Mb / s的下行峰值数据传输速率。由于上行MIMO未受聘在首次发布的LTE标准,因此上行峰值数据传输速率
9、被限制在86 Mb / s的20兆赫带宽。除了峰值数据传输速率的改善外,LTE系统提供两到四倍较高的细胞相对推出6 HSPA系统的频谱效率。在小区边缘的吞吐量为HSPA的部署,同时保持同一站点的位置观察到类似的改进。在延迟方面,LTE无线接口和网络提供了一个数据包从网络到UE的传输延迟小于10毫秒的能力。1.3演进到4G 移动Wi和UMB无线电接口属性表和表1.1给出的LTE属性表是非常相似。这三个系统都是支持灵活的带宽,下行的OFDMA和MIMO方案,FDD / TDD的双工。有如一些分歧,就是在LTE上行SC-FDMA的基于OFDMA技术在移动Wi和UMB上。三个系统的性能有所不同,因此预
10、计将有微小的差别。 类似于IMT-2000的主动性, ITU-R的5D工作组指出的IMT-Advanced系统的要求。其中,这些要求包括平均下行100 Mbit / s的广域网数据传输速率,最高可达1 Gbit / s的本地访问和低流动性的情景。此外,在世界无线电通信大会上(WRC-2007),最大的428兆赫的新频谱被确定为IMT系统,其中还包括一个在全球性的基础上分配136兆赫的频谱。 3GPP和IEEE 802 LMSC正在积极发展自己的标准,以提交IMT-Advanced为目标,LTE和IEEE802.16的标准是要进一步提高系统的频谱效率和数据传输速率,同时支持各自的早期版本的向后兼
11、容性。其中几个增强,包括支持一个大于20 MHz的带宽和较高阶MIMO的LTE-Advanced和IEEE 802.16标准发展的一部分,目前正在讨论中,以满足IMT-Advanced的要求。2网络架构和协议 LTE的网络结构设计与无缝移动性,质量和服务质量(QoS)的最小延迟支持分组交换流量的目标。分组交换的方式,允许所有服务,包括对语音通过数据包连接的支持。结果一个高度简化的平坦架构只有两个节点,即演变节点B(ENB)和移动性管理实体/网关(MME /毛重)。相反的,在目前的3G系统的分层网络架构有更多的网络节点。一个重大变化是,从数据路径和无线网络控制器(RNC)被淘汰,到现在在ENB纳
12、入其职能。在单个节点接入网络的好处是减少延迟和多个eNB到RNC的处理负荷分布。消除在接入网络的RNC是可能的,一方面是因为LTE系统不支持宏多样性或软切换。 在这一章中,我们讨论了单播和广播流量,QoS架构和接入网络的移动性管理的网络体系结构设计。此外我们还简要讨论2层结构和不同的逻辑,运输和物理信道,随着它们的映射问题。2.1网络架构 所有的网络接口都基于IP协议。通过S1接口的互连,如在图2.1所示的eNBs通过X2接口和MME /毛重实体。 S1接口支持MME的/毛重和eNBs的1之间的一对多的关系。 eNB和MME之间的功能分割关系图如图2.2所示。两个实体的逻辑网关即服务网关(GW
13、)和分组数据网网关(GW)。S-GW作为本地移动锚转发和接收数据包,并服从ENB -UE的服务。与外部分组数据网络(如Internet)和IMS(PDNS)的P-GW的接口。在P-GW还执行了多个IP地址分配,执行政策,包过滤和路由等功能。 MME是一个信号的唯一实体,因此,用户的IP数据包是不通过MME的。一个优势是一个单独的网络实体的信令信号和交通网络容量可以独立成长。 MME的主要职能是包括控制和执行寻呼转播的空闲模式UE的可达性,跟踪区列表管理,漫游,认证,授权,P-GW/S-GW选择,承载管理,包括专用的承载建立,安全谈判NAS信令等。 进化节点B实现节点B的功能,以及传统上RNC中
14、实现的协议。 eNB的主要功能是报头压缩,加密和数据包的可靠传递。在控制方面,ENB采用,如admissioncontrol和无线资源管理的职能。在单个节点接入网络的好处是减少延迟和RNC的处理负载分布到多个eNB。 图2.1 网络架构。 图2.2eNB和MME /毛重之间的功能分割。 在图2.3的用户平面协议中,我们注意到,分组数据汇聚协议(PDCP)和无线链路控制(RLC)传统RNC的网络侧终止层。图2.3用户平面协议。 附件2:外文原文(复印件) Introducing WPF The cellular wireless communications industry witnessed
15、 tremendous growth in the past decade with over four billion wireless subscribers worldwide. The first generation 1G analog cellular systems supported voice communication with limited roaming. The second generation 2G digital systems promised higher capacity and better voice quality than did their a
16、nalog counterparts. Moreover, roaming became more prevalent thanks to fewer standards and common spectrum allocations across countries particularly in Europe. The two widely deployed second-generation 2G cellular systems are GSM global system for mobile communications and CDMA code division multiple
17、 access. As for the 1G analog systems, 2G systems were primarily designed to support voice communication. H In later releases of these standards, capabilities were introduced to support data transmission. However, the data rates were generally lower than that supported by dial-up connections. The IT
18、U-R initiative on IMT-2000 international mobile telecommunications 2000 paved the way for evolution to 3G. A set of requirements such as a peak data rate of 2 Mb/s and support for vehicular mobility were published under IMT-2000 initiative. Both the GSM and CDMA camps formed their own separate 3G pa
19、rtnership projects 3GPP and 3GPP2, respectively to develop IMT-2000 compliant standards based on the CDMA technology. The 3G standard in 3GPP is referred to as wideband CDMA WCDMA because it uses a larger 5 MHz bandwidth relative to 1.25 MHz bandwidth used in 3GPP2s cdma2000 system. The 3GPP2 also d
20、eveloped a 5 MHz version supporting three 1.25 MHz subcarriers referred to as cdma2000-3x. In order to differentiate from the 5 MHz cdma2000-3x standard, the 1.25 MHz system is referred to as cdma2000-1x or simply 3G-1x. The first release of the 3G standards did not fulfill its promise of high-speed
21、 data transmissions as the data rates supported in practice were much lower than that claimed in the standards. A serious effort was then made to enhance the 3G systems for efficient data support. The 3GPP2 first introduced the HRPD high rate packet data 1 system that used various advanced technique
22、s optimized for data traffic such as channel sensitive scheduling, fast link adaptation and hybrid ARQ, etc. The HRPD system required a separate 1.25 MHz carrier and supported no voice service. This was the reason that HRPD was initially referred to as cdma2000-1xEVDO evolution data only system. The
23、 3GPP followed a similar path and introduced HSPA high speed packet access 2 enhancement to the WCDMA system. The HSPA standard reused many of the same data-optimized techniques as the HRPD system. A difference relative to HRPD, however, is that both voice and data can be carried on the same 5 MHz c
24、arrier in HSPA. In parallel to HRPD, 3GPP2 also developed a joint voice data standard that was referred to as cdma2000-1xEVDV evolution data voice 3. Like HSPA, the cdma2000-1xEVDV system supported both voice and data on the same carrier but it was never commercialized. In the later release of HRPD,
25、 VoIP Voice over Internet Protocol capabilities were introduced to provide both voice and data service on the same carrier. The two 3G standards namely HSPA and HRPD were finally able to fulfill the 3G promise and have been widely deployed in major cellular markets to provide wireless data access.1.
26、1 Beyond 3G systems While HSPA and HRPD systems were being developed and deployed, IEEE 802 LMSC LAN/MAN Standard Committee introduced the IEEE 802.16e standard 4 for mobile broadband wireless access. This standard was introduced as an enhancement to an earlier IEEE 802.16 standard for fixed broadba
27、nd wireless access. The 802.16e standard employed a different access technology named OFDMA orthogonal frequency division multiple access and claimed better data rates and spectral efficiency than that provided by HSPA and HRPD. Although the IEEE 802.16 family of standards is officially called Wirel
28、essMAN in IEEE, it has been dubbed Wi worldwide interoperability for microwave access by an industry group named the Wi Forum. The mission of the Wi Forum is to promote and certify the compatibility and interoperability of broadband wireless access products. The Wi system supporting mobility as in I
29、EEE 802.16e standard is referred to as Mobile Wi. In addition to the radio technology advantage, Mobile Wi also employed a simpler network architecture based on IP protocols The introduction of Mobile Wi led both 3GPP and 3GPP2 to develop their own version of beyond 3G systems based on the OFDMA tec
30、hnology and network architecture similar to that in Mobile Wi. The beyond 3G system in 3GPP is called evolved universal terrestrial radio access evolved UTRA 5 and is also widely referred to as LTE Long-Term Evolution while 3GPP2s version is called UMB ultra mobile broadband 6 as depicted in Figure
31、1.1. It should be noted that all three beyond 3G systems namely Mobile Wi, LTE and UMB meet IMT-2000 requirements and hence they are also Figure 1.1. Cellular systems evolution.Table 1.1. LTE system attributes.part of IMT-2000 family of standards.1.2 Long-Term Evolution LTE The goal of LTE is to pro
32、vide a high-data-rate, low-latency and packet-optimized radio-access technology supporting flexible bandwidth deployments 7. In parallel, new network architecture is designed with the goal to support packet-switched traffic with seamless mobility, quality of service and minimal latency 8 The air-int
33、erface related attributes of the LTE system are summarized in Table 1.1. The system supports flexible bandwidths thanks to OFDMA and SC-FDMA access schemes. In addition to FDD frequency division duplexing and TDD time division duplexing, half-duplex FDD is allowed to support low cost UEs. Unlike FDD
34、, in half-duplex FDD operation a UE is not required to transmit and receive at the same time. This avoids the need for a costly duplexer in the UE. The system is primarily optimized for low speeds up to 15 km/h. However, the system specifications allow mobility support in excess of 350 km/h with som
35、e performance degradation. The uplink access is based on single carrier frequency division multiple access SC-FDMA that promises increased uplink coverage due to low peak-to-average power ratio PAPR relative to OFDMA. The system supports downlink peak data rates of 326 Mb/s with 4 4 MIMO multiple in
36、put multiple output within 20 MHz bandwidth. Since uplink MIMO is not employed in the first release of the LTE standard, the uplink peak data rates are limited to 86 Mb/s within 20 MHz bandwidth. In addition to peak data rate improvements, the LTE system provides two to four times higher cell spectr
37、al efficiency relative to the Release 6 HSPA system. Similar improvements are observed in cell-edge throughput while maintaining same-site locations as deployed for HSPA. In terms of latency, the LTE radio-interface and network provides capabilities for less than 10 ms latency for the transmission o
38、f a packet from the network to the UE.1.3 Evolution to 4G The radio-interface attributes for Mobile Wi and UMB are very similar to those of LTE given in Table 1.1. All three systems support flexible bandwidths, FDD/TDD duplexing, OFDMA in the downlink and MIMO schemes. There are a few differences su
39、ch as uplink in LTE is based on SC-FDMA compared to OFDMA in Mobile Wi and UMB. The performance of the three systems is therefore expected to be similar with small differences Similar to the IMT-2000 initiative, ITU-R Working Party 5D has stated requirements for IMT-advanced systems. Among others, t
40、hese requirements include average downlink data rates of 100 Mbit/s in the wide area network, and up to 1 Gbit/s for local access or low-mobility scenarios. Also, at the World Radiocommunication Conference 2007 WRC-2007, a imum of a 428 MHz new spectrum is identified for IMT systems that also includ
41、e a 136 MHz spectrum allocated on a global basis. Both 3GPP and IEEE 802 LMSC are actively developing their own standards for submission to IMT-advanced. The goal for both LTE-advanced 9 and IEEE 802.16 m 10 standards is to further enhance system spectral efficiency and data rates while supporting b
42、ackward compatibility with their respective earlier releases. As part of the LTE-advanced and IEEE 802.16 standards developments, several enhancements including support for a larger than 20 MHz bandwidth and higher-order MIMO are being discussed to meet the IMT-advanced requirements.2 Network archit
43、ecture and protocolsThe LTE network architecture is designed with the goal of supporting packet-switched traffic with seamless mobility, quality of service QoS and minimal latency. A packet-switched approach allows for the supporting of all services including voice through packet connections. The re
44、sult in a highly simplified flatter architecture with only two types of node namely evolved Node-B eNB and mobility management entity/gateway MME/GW. This is in contrast to many more network nodes in the current hierarchical network architecture of the 3G system. One major change is that the radio n
45、etwork controller RNC is eliminated from the data path and its functions are now incorporated in eNB. Some of the benefits of a single node in the access network are reduced latency and the distribution of the RNC processing load into multiple eNBs. The elimination of the RNC in the access network w
46、as possible partly because the LTE system does not support macro-diversity or soft-handoff. In this chapter, we discuss network architecture designs for both unicast and broadcast traffic, QoS architecture and mobility management in the access network. We also briefly discuss layer 2 structure and d
47、ifferent logical, transport and physical channels along with their mapping.2.1 Network architecture All the network interfaces are based on IP protocols. The eNBs are interconnected by means of an X2 interface and to the MME/GW entity by means of an S1 interface as shown in Figure 2.1. The S1 interf
48、ace supports a many-to-many relationship between MME/GW and eNBs 1 The functional split between eNB and MME/GW is shown in Figure 2.2. Two logical gateway entities namely the serving gateway S-GW and the packet data network gateway P-GW are defined. The S-GW acts as a local mobility anchor forwardin
49、g and receiving packets to and from the eNB serving the UE. The P-GW interfaces with external packet data networks PDNs such as the Internet and the IMS. The P-GW also performs several IP functions such as address allocation, policy enforcement, packet filtering and routing. The MME is a signaling only en