DSL Advances

2.5. Discrete Multichannel Transmission (DMT)

The concept of multichannel transmission is one often used against a formidable adversary, following the old adage: “divide and conquer,” where the adversary in this case is the difficult transmission characteristic of the DSL twisted pair. Multichannel methods transform the DSL transmission line into hundreds to thousands of tiny transmission lines, each of which is easy to transmit on. The overall data rate is the sum of the data rates over all the easy channels. The most common approach to the “division”is transmission in non-overlapping narrow bands. The “conquer” part is that a simple line code on each such channel achieves best performance without concern for the formidable difficulty of intersymbol ...