Some basic standards are introduced first.Then the use of single-carrier QAM and multi-carrier DMT are contrasted.Frequency division duplexing (FDD) and residential gateway are also discussed.

• 首先介绍了VDSL的一些基本规范，然后就VDSL的关键技术，如QAM和DMT调制技术、频分复用、以及用户区网关等作了描述。