The Benefits of Discrete Multi-Tone (DMT) Modulation for VDSL Systems

The increasing demand for high-bandwidth services such as corporate communications, fast Internet access and digital audio and video delivery presents both a great challenge and a great opportunity. To respond to this challenge, and to take advantage of the opportunity, the telecommunications industry is developing communication equipment based on clever implementations of highly efficient modulation techniques. Most of these efforts are focused on the last mile as this is the bottleneck for providing high performance bandwidth to consumers [1]. Additionally, since the telephone line has the highest penetration rate of all media to consumers, (at last count, over 1 billion [2] lines worldwide), solving the last mile problem implicitly requires that the bandwidth be delivered over telephone lines. This paper discusses DMT's advantages over QAM from the perspectives of performance, flexibility, compatibility, and operational issues, all of which are extremely important to a service provider.