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随着Internet用户的爆炸式增长,网络在商业领域的应用和提供的多媒体服务也得以迅猛推广,尼葛洛庞帝所描述的数字化生存正在演变为现实。要充分享受Internet上的各种服务,用户必须以某种方式接入网络以实现接入网的数字化、宽带化,提高上网速度。光纤到户(FTTH)是用户网今后发展的必然方向,但由于光纤用户网的成本过高,在今后的十几年甚至几十年内大多数用户网仍将继续使用现有的铜线环路。于是近年来人们提出了多项过渡性的宽带接入网技术,包括N-ISDN、Cable Modem、ADSL等,其中ISDN、ADSL以各自特有的技术优势在很长一段时间内在接入网技术领域居于主导地位。下面就从各自的主要方面详细做个介绍。
With the explosive growth of Internet users, the use of networks in the commercial domain and the provision of multimedia services have also been rapidly proliferating and the digital existence described by Negroponte is evolving into reality. To fully enjoy the various services on the Internet, users must somehow access the network in order to achieve the digital access network, broadband, improve Internet access speed. Fiber to the home (FTTH) is the inevitable direction for the future development of subscriber networks. However, because of the high cost of fiber subscriber networks, most subscriber networks will continue to use the existing copper ring in the next ten or even decades . So in recent years, many transitional broadband access network technologies have been proposed, including N-ISDN, Cable Modem and ADSL. Among them, ISDN and ADSL occupy a very long period of time in the access network technology field leading position. Here’s a detailed introduction from each of their major aspects.