为了适应电信业务量的迅猛发展，到目前为止，电信骨干网已基本实现了宽带化。但从电信端局到最终用户的接入网部分却发展滞后，依然以普通电话双绞铜线的接入方式为主，成为制约宽带业务的“瓶颈”。为此，人们提出了多种将接入网宽带化的方案。这些宽带化方案主要分为三大类 In order to adapt to the rapid development of telecom traffic, so far, the telecommunications backbone network has basically realized the broadband. However, the access network from the telecommunication end-user to the end-user has lagged behind and still takes the access mode of ordinary telephone twisted-pair copper wire as the main bottleneck restricting broadband services. To this end, people have proposed a variety of access network broadband program. These broadband programs are mainly divided into three categories