Vectored DSL: Potential, Implementation Issues and Challenges

This paper investigates specific techniques suitable for Vectored DSL, their performance, complexity and practical implementation. More specifically, various Vectored DSL techniques for both upstream and downstream transmission are discussed, including the Tomlinson-Harashima Pre-coder (THP), Diagonalizing Pre-coder (DP), Zero-Forcing (ZF) canceller, and Decision-Feedback (DF) canceller. A thorough discussion on some of the practical implementation aspects of Vectored DSL is provided. In particular, various implementation challenges are discussed, including computational load, memory storage, line management, partial crosstalk cancellation, and the effect of imperfect channel knowledge. As well, the potential gains and challenges of combining Phantom DSL and Vectored DSL are also discussed. Illustrative examples are provided based on both measured data and channel models to compare the various Vectored DSL techniques and their practical implementation challenges.