光纤接入网技术毕业论文外文翻译.doc

一、英文原文Optical fiber access network technologyDuring the early 1980s, analog cellular telephone systems were experiencing rapid growth in Europe, particularly in Scandinavia and the United Kingdom, but also in France and Germany. Each country developed its own system, which was incompatible. The entire telecommunication network according to network function is divided into three sections: switching, transmission,and access. Access to telecommunications business transparent to users, transmit specific, access to local switch and the user that the connection between the parts, usually include subscriber line transmission system, reuse equipment, crossing connection device or user/network terminal equipment. And actually pick for business entity is business nodes. 1. Access network development process 1.1 Access Network （AN: Access by business） refers to a node interface （SNI） and related users Network interface （UNI） between a series of transmit entity （such as line facilities and transmission facilities） for transmission consisting of telecommunication business provide the required transmit load capacity, implementation system configurations percentile management interface via and management. Access can be seen as with business and application irrelevant transmission network, mainly finish crossing connection, reuse and transmission function, it is transparent to users of signaling. Based on modern of telecommunication network access network is integrated service access, simple local voice access will be increasingly cannot meet the requirements, the voice, data and image comprehensive access is becoming access network development trend. After years of development, access network define though does not change, but its connotation and forms has changed significantly. Superior traditional access network integrated optical fiber access network will be users access the future developing trend. Optical fiber access from SNI to UNI refers to all or part of the access network by using optical fiber as medium. ITU - T about access network recommendations indicate that fiber, user access system is composed of three parts: optical line terminal（OLT）, optical distribution network （ODN） and optical network unit （ONU）. 1.2According to the requirement of system access framework and the important characteristics, access network can be summarized as the following: 1.2.1 Access to access business provides bearing capacity, achieve business transparent transfer. 1.2.2. The access is transparent to users signaling, except for some users signaling format conversion outside, signaling and business processing function is still in business node. 1.2.3 The introduction of should not be restricted access all kinds of existing access types and business, access network should through the limited standardization interface and business node connected. 1.2.4Access network have independent from the business node in the network management system, this system through the standardized interfaces connected TMN, access network operation for implementation TMN, maintenance and management. 2 .fiber structure 2.1general linear structure. Refer to the public bus, fiber as each user terminals through direct connect with bus coupler network structure. Its characteristic is sharing backbone fiber, save lines to remove node investment, the demand is higher, dynamic range, interfere with each other effect is small. Defect is loss of accumulation, the backbone fiber user acceptance dependence is strong. 2.2 ring structure. Refers to all share a fiber optic link node, fiber optic link its end to end the closed loop network structure. Characteristic is self-healing, namely can be realized without intervention, the network can be in a relatively short period of time to recover from failure have preached business, high reliability. Defect is hanged by the number of users of monocylic limited, polycyclic interchange is relatively complex, not suitable for CATV, etc FenPeiXing business. 2.3star structure. This structure is actually point-to-point way, each user terminals in the central node through with control and switch functions of the astral couplers exchange information. Characteristics of simple structure, maintenance is convenient and easy to upgrade and expansion between, each user relatively independent, good secrecy, business adaptability. Defect is higher, networking required fiber cost of poor flexibility, high reliability requirements of central node. 2.4 tree structure. Similar to the branches, a hierarchical structure, shape in transfer boxes and FenXianHe place adopts multiple optical distributor, will signal filtering down top end innings allocation, have strong control coordination. Characteristic is suitable for broadcasting business. Defect is power loss is bigger, two-way communication difficulty bigger. 3The status of optical access network in the modern communicationOptical fiber in realizing national information modernization access plays a more and more important role, is an indispensable part of modern communications network. Modern communications network basic realized based on fiber backbone transmission and exchange, and access section is still restricted modern telecommunications further development and improvement of the bottleneck, therefore, to construction of national information infrastructure （NII）, access network is the key. Access network technology development, will result in great changes of telecommunications and information network, namely, voice, data, video, etc. Various kinds of information transmission, comprehensive business together for implementing the resources sharing, and gradually optimized communication network, greatly improving network benefits. Two optical fiber optical transmission technology access with the combination of the access technology 3.1 Light transmission technology development and evolution Since 1979, the human use of optical fiber as communication mode, optical transmission technology experience since from analog to digital, from PDH to sdh-based WDM, from passive and active to a series of MSTP from SDH to the development and evolution process, transmission capacity and reliability, the transmission distance such indicators have reached a very high level. The current mainstream of optical transmission technology is still SDH, STM - 1/4/16/64/256 series synchronous transfer module has been achieved, including STM - 256 frame rate as high as 40Gbps. Based on SDH, fusion broadband data business multi-task transmitting platform （the MSTP） has also become the best choice for todays construction intracity networks, moreover elastic grouping ring （RPR） technology is also gradually become the direction of the development of a light transmission. The future will be optical transmission network to optical transmission network （otns） in the direction of development, many exchange, network otns choose road and other intelligent function will be implemented on light layer. Otns the intelligent network development degree can realize ASON intelligent optical network. 3.2 Light transmission technology and access technology constitute fiber access network The needs of the user, the diversification and broadband access technology from initial made of pure narrowband access to broadband access, size, and with integrated access to transmission platform requirement light more and more is also high. Optical transmission technology and access technology together constitute fiber access network system. Optical fiber access network in different stages of development of need to resort to the corresponding optical transmission means to achieve the operational load and transfer. With the light network will be dispersed access devices （OLT ONU） together with organic whole, form a unified fiber access network system. 二、英文翻译光纤接入网技术整个电信网按网络功能分为三个部分：传输网、交换网和接入网。接入网负责将电信业务透明传送到用户，具体而言，接入即为本地交换机与用户之间的连接部分，通常包括用户线传输系统、复用设备、交叉连接设备或用户/网络终端设备。而实际上接供业务的实体就是业务结点。一接入网的发展历程1.接入网（AN：Access Network）是指由业务节点接口（SNI）和相关用网络接口（UNI）之间的一系列传送实体（诸如线路设施和传输设施）所组成的为传送电信业务提供所需传送承载能力的实施系统，可经由Q3管理接口进行配置和管理。接入网可以被看作是与业务和应用无关的传送网，主要完成交叉连接、复用和传输功能，对用户信令来说是透明的。基于现代电信网的接入网是综合业务接入网，简单的本地话音接入将越来越不能满足需要，语音、数据、图像的综合接入正成为接入网的发展趋势。经过多年的发展，接入网的界定虽然没有变，但其内涵和形式发生了很大的变化。光纤接入网是指从SNI到UNI全部或者部分采用光纤作为媒质的接入网。ITU-T关于光纤接入网的建议指出，用户接入系统由三部分组成：局端设备（OLT）、光分配网络（ODN）和光网络单元（ONU）。2. 根据接入网框架和体制要求，接入网的重要特征可以归纳为如下几点： （1）接入网对于所接入的业务提供承载能力，实现业务的透明传送。 （2）接入网对用户信令是透明的，除了一些用户信令格式转换外，信令和业务处理的功能依然在业务节点中。 （3）接入网的引入不应限制现有的各种接入类型和业务，接入网应通过有限的标准化的接口与业务节点相连。 （4）接入网有独立于业务节点的网络管理系统，该系统通过标准化的接口连接TMN，TMN实施对接入网的操作、维护和管理。 二光纤的结构1.总线形结构。指以光纤作为公共总线、各用户终端通过耦合器与总线直接连接的网络结构。其特点是共享主干光纤，节约线路投资，增删节点容易，动态范围要求较高，彼此干扰效小。缺点是损耗积累，用户接受对主干光纤的依赖性强。 2.环形结构。指所有节点共用一条光纤链路，光纤链路首尾相连自成封闭回路的网络结构。特点是可实现自愈，即无需外界干预，网络可在较短的时间自动从失效故障中恢复所传业务，可靠性高。缺点是单环所挂用户数量有限，多环互通较为复杂，不适合CATV等分配型业务。3.星形结构。这种结构实际上是点对点方式，各