An adaptive multiuser power control algorithm for VDSL

This paper investigates optimal power control in a frequency selective multiuser interference network. The power control problem is modeled as a non-cooperative game. The existence and uniqueness of a Nash equilibrium in the game is established, and an iterative water-filling algorithm is proposed to reach the Nash equilibrium efficiently. It is shown that the Nash equilibrium point corresponds to a competitively optimal power allocation in the interference network. Based on this result, an adaptive power control algorithm for upstream VDSL power back-off is developed. The power control algorithm takes into account the loop transfer functions and cross-couplings, and allows the loops to negotiate the best use of power and frequency. This new algorithm is found to have a substantial performance improvement when compared to current methods