Optimal discrete bit loading for DMT-based DSL systems with equal-length loops

This letter examines a discrete bit-loading problem of upstream and downstream for discrete multitone digital subscriber lines with echo cancellation. Both far-end crosstalk and near-end crosstalk are taken into account. An optimal discrete bit-loading algorithm is developed when the loop lengths of all same-service users in a common binder are the same. Simulation results show that the optimal algorithm achieves a substantially higher data rate than existing suboptimal schemes.