摘要
介绍了ＸＤＳＬ 技术发展的过程，ＸＤＳＬ 系统的结构、原理和功能及ＸＤＳＬ 设备，认为为使世界上已建的数亿对金属缆线能适应宽带多媒体通信的需要，
The process of technical development, system structure, principle, functions and equipment of XDSL are introduced in the paper. It thinks that the selective reform method is to use XDSL access network technology in order to make hundreds of millions of pair of metal cables that had been built to meet the need of broadband multimedia communications.
关键词
数字用户环路
金属双绞线
全双工传输
Digital subscriber loops
Metal twisted pair line
Full duplex transmission
