A Robustness Analysis of Game-Theoretic CDMA Power Control

摘要

This paper studies robustness of a gradient-type CDMA uplinkpower control algorithm with respect to disturbances and time-delays. This problem is of practical importance because unmodeled secondaryinterference effects from neighboring cells play the role ofdisturbances, and propagation delays are ubiquitous in wireless datanetworks. We first show L_p-stability, for p in [1,infity], withrespect to additive disturbances. We pursue L_{infity}-stability withinthe input-to-state stability (ISS) framework of Sontag [7], whichmakes explicit the vanishing effect of the initial conditions. Next,using the ISS property and a loop transformation, we prove that globalasymptotic stability is preserved for sufficiently small time-delaysin forward and return channels. For larger delays, we achieve globalasymptotic stability by scaling down the step-size in the gradientalgorithm.