通信工程外文翻译--三网融合的物理网络选择

1、附录B 译文三网融合的物理网络选择 所谓的“三网”，是指电信业务网、广播电视网和计算机网，但这并不是在物理概念上的分割，而是在业务上的分割。实际的网络（即物理网络）其实只有通信网和广播电视网，其名称也是因模拟领域业务和技术相关而形成的。因为在模拟领域，不同的业务对传输方法有不同的要求，因而形成不同的网络。因此，从某种意义上说，“三网”都是模拟传输的产物。在数字领域，所有的语言、文字、图片和图像等信息都是以“0”和“1”的数字信号出现，因此对数字网来说不存在几个网的问题，多个业务网完全可以共存于一个物理网中。信源的数字化导致了信息的汇聚，进而导致了三网的融合。 所谓“三网融合”，指的是将计算机网

2、、电话网和电视网有机地融合起来，以降低总的成本投入，方便人们的使用，提高效率，产生更多的经济效益和社会效益。我们知道，技术进步总是从一个方向、一个领域或一种装置上逐步取得突破的，而人类对技术的需求却是以自我为中心的，而且是全方位的，这就是“三网融合”的原始驱动力。“三网融合”正逐渐成为世人瞩目的焦点，同时也孕育着巨大的市场机会。尤其是在二十世纪末，这一领域已经发生了突破性的变化。外国的大型计算机企业，如微软、索尼等公司，已经把“三网融合”作为其今后发展的业务重点而加以大力推进。前不久闹得沸沸扬扬的微软“维纳斯”计划就是瞄准了这一市场。就国内而言，北京、上海、青岛、重庆、江西等省市已经在开展这方

3、面的探索，如上海广电集团研制的“SGIT三网合一”多媒体信息网络系统，就准备在在其公司开发的居民住宅小区进行试运行；而重庆华信高技术公司日前则声称其成功地开发了“三网合一”的HFC用户接入系统，能够利用有线电视网并行传输电视、电话和计算机信息；中信国安、海信电器等上市公司也已经在这一领域迈出了扎实的一步。总的说来，国内已有不少地方和企业瞄准了“三网合一”广阔的市场前景，准备或已经实施其抢占滩头的战略计划。但就目前而言，他们之中大多数还处于投入阶段，现阶段还没有收到显著的效益，但有一点是不容置疑的，那就是：国内、国外有远见的企业已经在悄悄瓜分这一市场，星星之火将在不久的将来将演成燎原之势。 纵观

4、世界IT产业，自康柏和Digital之间的“世界购并”后，1998年6月全球的第二大电信公司棗北方电信以91亿美元收购了全球的第三大计算机网络公司棗贝网，标志着业务融合的屏障开始大片拆除，一个大范围的电信产业和计算机产业走向统一的浪潮即将来到。全新的企业形象将引出全新的产业格局。就国内而言，信息产业部的成立，标志着我国产业格局也将发生巨大的变化。但我国的电信网、有线电视网和计算机网是否能马上合并成一个统一的网络呢？由于长期的地方经济保护主义和传统经济模式的影响，加上电信和广播电视网本身技术层面及经营模式上的差别，要在我国实现三网融合，仍存在着大量亟待解决的问题。 我国三网的发展和数字化的实现，

5、都是在原有业务上发展起来的。因此它们之间存在着不兼容的问题。如IP网近年来以惊人的摩尔速度发展，千兆路由器已进入实用阶段。但其IP协议是由互联网业务发展而来的，主要适用于小容量非实时业务，因此在用于大容量的广播电视时，大容量广播电视实时传输和质量控制方面仍存在着明显的问题。同时，经济可行性问题也非常突出。据有关资料统计，截止到1999年，我国互联网出口不足80Mbps，而上网用户已达140万户，占用通道平均5714bps，若考虑少数大容量用户，一般用户远小于这个数字，但来自每个用户的收益远远超过相应的有线电视，要在IP网上挤出几百兆来实现电视的接入是不可能的。同样，也很难要求在使用300-34

6、00Hz带宽已经实现可观收入的情况下用原有通信网来实现电视的接入。有线广播电视网的业务是由其性质所决定的，主要是传播党、政府、人民需要的广播电视信息。当然，可以利用网络的优势，开发多功能业务。但想在网上完全取代固定电话公司的话音业务也是不现实的。因此，目前在一个网络中实现三种业务的三网合一是不现实的。这也是业界为什么逐步用“三网融合”取代“三网合一”的提法的主要原因。三网只有在社会主义市场经济的条件下，以原有业务为主，逐步开展其他网络业务，并引入适度的竞争，才能推进我国信息产业的发展，并进而逐步走向三网融合。电信业务网 电信业务网是以电话网为基础逐步发展起来。目前信息到户主要是双绞线，通过交换

7、机与骨干网相连。电话网是最早进行数字化的，传输方式逐步向光纤到户发展，传输协议从准同步体系（PDH）到同步体系（SDH）进而到非同步转移模式（ATM）发展，但由于发展的不平衡，尚不能做到全网传输和交换的数字化。虽然有非对称用户环路（ADSL）和高速用户环路（VDSL）等方式，速率可以从几Mbps到几十Mbps，但整个网络的流通能力受到双绞线传输容量这一瓶颈的抑制。目前电话双绞线上网的主流频率为56K，其物理极限为64K，潜力非常有限。这将是电信业务网一个难以逾越的障碍。计算机网 计算机网络初期主要是局域网，远程网是在国际互联网大规模发展后才迅速进入平常百姓家庭的，目前主要依赖于电信网，因此同样

8、受到到户双绞线传输容量和CABLE MODEM速度的限制，但其互联网协议众多的优越性正在被其他网络所采用。广播电视网 我国的广播电视网络是全国最大的公众信息网络，由于其带宽比电话要宽得多，因而其网络具有一定优势。特别是近十年来发展起来的广播电视网的后起之秀棗有线电视网，具有网络技术设备先进、光缆为主干线；贯通全国和各省市首府及其大部分的城镇；宽带双向光纤同轴电缆混合网（HFC）入户的优点；与电话接入方式相比，其传输的带宽约为电话线的一万倍，而且在有线电视的同一根同轴电缆上，利用频分技术，可以同时看电视、打电话、上计算机网，且互不干扰。而不象电信网接入时会出现不能同时上计算机网和打电话的现象。目

9、前有线电视网已拥有用户终端数7700万户，是世界上用户规模最大的有线电视网络。但由于其发展不平衡，全国各地网络分配网带宽不一，使用器材离散性大等诸多原因，因而也只有在对现有网络进行不同程度的升级改造之后，才有进一步拓展广播电视业务以外的其它增值业务的可能。从以上的分析中可以看出，目前三网在技术上各有长短，但有线电视网既可同时支持模拟业务和数字业务，又拥有丰富的带宽资源和广泛的受众资源，在适应性和可改造性方面，都占有一定的优势。在三网逐渐走向融合的大前提下，及早确定最终的物理网络，将避免重复低效的投资，有利于我国信息业的长远发展。我个人认为，无论是从技术角度还是从经济实用角度出发，广播电视网络中

10、的有线电视网都将是三网融合之物理网络的最佳选择。 附录C 外文原文Triple play of the physical network selection The so-called "triple play" refers to the telecommunications business network, radio and TV and computer networks, but this is not in the physical concept of the split, but split in the business. The actual netw

11、ork (physical network) is in fact only communication networks and broadcast networks, its name is due to the analog domain, business and technology-related formation. Because in the analog domain, the different business have different requirements for the transmission method, resulting in a differen

12、t network. Therefore, in a sense, the "triple play" product of analog transmission. In the digital domain, all of the language, text, pictures and images and other information are "0" and "1" digital signals, and therefore does not exist a few network for digital networ

13、k, multiple service network can be coexist on a single physical network. The source of digital has led to the convergence of information, which led to the integration of the three networks. The so-called "triple play", referring to the computer network, telephone network and television net

14、work organic blend to reduce the total cost of investment, to facilitate the use of people, to improve efficiency, generate more economic and social benefits. We know that technological progress is always from one direction, a field or a device gradually achieve a breakthrough, human demand for tech

15、nology is self-centered, and all, this is the "triple play" the original driving force. "Triple play" is becoming the focus of world attention, but also gave birth to a huge market opportunity. Especially at the end of the twentieth century, this area has occurred a breakthrough

16、change. Large foreign computer companies such as Microsoft, Sony and other companies, the "triple play" as the focus of its future development to be vigorously promoted. Not long ago ignited Microsoft's "Venus" program is aimed at this market. Domestically, Beijing, Shanghai,

17、 Qingdao, Chongqing, Jiangxi and other provinces and cities in carrying out this exploration, such as developed by the Shanghai SVA Group "SGIT triple play" multimedia information network system, ready in his company to develop the residential areas in the test run; Chongqing Huaxin high-t

18、ech company has claimed that it has successfully developed a "triple play" of HFC user access system can take advantage of the cable television network parallel transmission of television, telephone and computer information;CITIC Guoan, Hisense Electric and other listed companies have also

19、 taken a solid step in this field. In general, the country has a lot of places and businesses aimed at the "triple play" broad market prospects, preparation or implementation of its strategic plan to seize the beachhead. But for now, most of them are still in the input stage, has yet to re

20、ceive significant benefits, but there is no question, that is: domestic, foreign, far-sighted companies have quietly carved up market, the spark will in the near future evolves into a prairie fire. Looking at the world IT industry, since the World acquisitions Compaq and Digital, the date of June 19

21、98 the world's second largest telecommunications company Northern Telecom for $ 9.1 billion acquisition of the world's third-largest computer network dates shellfish net, barrier marks the business integration of large tracts removed, and a wide range of telecommunications industry and compu

22、ter industry toward a unified wave coming. The new corporate image will lead to a new industrial pattern. Domestically, the establishment of the Ministry of Information Industry, indicates that China's industrial structure will also change dramatically.China's telecommunications networks, ca

23、ble TV and computer networks can be immediately merged into a unified network? Due to the impact of long-term local economic protectionism and traditional economic model, coupled with differences in the telecommunications and broadcast networks the technical level and business model, in China, tripl

24、e play, there are still a lot of problems to be solved. The development of China's three networks and digital implementation, developed the original business. There are incompatibility issues between them.Such as the IP network in recent years to the development of the amazing speed of Moore, gi

25、gabit router has entered the practical stage. But the IP protocol from the Internet business development, is mainly applied to the non-real-time services for small capacity, in radio and television for high-capacity, high-capacity real-time transmission of radio and television, and quality control,

26、there are still obvious problems. At the same time, the economic viability of problem is also very prominent. According to statistics, in 1999, the export of China's Internet to 80Mbps. Internet users has reached 1.4 million, occupy channels average 5714bps, considering the small number of high-

27、capacity users, the average user is far less than this figure, but from each The user's benefits far exceed the corresponding cable TV access is not possible to squeeze a few megabytes in IP networks.Similarly, it is difficult with the existing communication network to access TV in the case of 3

28、00-3400Hz bandwidth has been achieved substantial revenues. The business of cable television network is determined by its very nature, is the dissemination of the party, government and people need radio and television information. Of course, you can use the advantages of the network, the development

29、 of multi-function business. But would like to completely replace the fixed-line telephone company's voice business online is unrealistic. Therefore, at present in a network of three business triple-play is not realistic. This is also the industry's why gradually with the main reason of the

30、"triple play" instead of "triple play" of the formulation. The three networks only under the conditions of the socialist market economy, mainly to the existing business, a gradual development of other network services, and the introduction of an appropriate degree of competition

31、in order to promote the development of China's information industry, and thus gradually moving towards triple play. Telecom Services Network Telecommunications service network is the telephone network based on the progressive development. Information to the home is a twisted pair, connected thro

32、ugh a switch and the backbone network. Telephone network from the quasi-synchronous hierarchy (PDH) to synchronous hierarchy (SDH) and then to the asynchronous transfer mode (ATM) is a pioneer in digital transmission gradually to the FTTH development, transport protocol, but because of the imbalance

33、 in development, still can not do the whole network digital transmission and switching.Although the asymmetric subscriber line (ADSL) and high-speed subscriber loop (VDSL) and other ways, the rate can range from a few Mbps to tens of Mbps, but the flow capacity of the entire network by the inhibitio

34、n of the twisted pair transmission capacity bottleneck. Internet telephone twisted pair mainstream frequency of 56K, its physical limit of 64K, the potential is very limited. This will be the telecommunications service network is an insurmountable obstacle. Computer Network The early stage of comput

35、er network LAN, remote network is quick access to large-scale development of the Internet before the ordinary people, families, mainly dependent on the telecommunications network, and therefore subject to the same home twisted pair transmission capacity and the CABLE MODEM speed limit, butThe many a

36、dvantages of Internet Protocol is used by other network.Radio and television networksChina's Radio and Television Network China's Radio and Television Network is the nation's largest public information network, due to a much wider bandwidth than telephone, and thus the network has certai

37、n advantages. In particular, is a rising star date of the broadcast networks over the past decade the development of cable television, network technology, advanced equipment, fiber optic cable main trunk; through national and provincial capitals and most of its cities and towns; broadband bi-directi

38、onal fiber-coaxial hybrid network(HFC) the advantages of home; and telephone access mode, the transmission bandwidth of about a million times in the telephone line, and cable TV with a coaxial cable, using the frequency division technique, you can also watch TV , phone calls, computers on the network, and without disturbing each other. Not like the telecommunication network access will not at the same time on the computer network and cal