Distributed multiuser power control for digital subscriber lines

TLDR

The study addresses multiuser power control in frequency‑selective interference channels. The authors propose an iterative water‑filling algorithm to efficiently reach the Nash equilibrium. They model the channel as a noncooperative game with a unique Nash equilibrium and present a distributively implemented iterative water‑filling algorithm that accounts for loop transfer functions and cross couplings to negotiate optimal power and frequency allocation. The algorithm yields significant performance gains over existing methods for upstream power backoff in very‑high‑bit‑rate DSL and downstream spectral compatibility in ADSL.

Abstract

This paper considers the multiuser power control problem in a frequency-selective interference channel. The interference channel is modeled as a noncooperative game, and the existence and uniqueness of a Nash equilibrium are established for a two-player version of the game. An iterative water-filling algorithm is proposed to efficiently reach the Nash equilibrium. The iterative water-filling algorithm can be implemented distributively without the need for centralized control. It implicitly takes into account the loop transfer functions and cross couplings, and it reaches a competitively optimal power allocation by offering an opportunity for loops to negotiate the best use of power and frequency with each other. When applied to the upstream power backoff problem in very-high bit-rate digital subscriber lines and the downstream spectral compatibility problem in asymmetric digital subscriber lines, the new power control algorithm is found to give a significant performance improvement when compared with existing methods.