Achievable-SIR-based predictive closed-loop power control in a CDMAmobile system

摘要

A power control algorithm with two prediction models based on annachievable signal-to-interference power ratio (SIR) has been proposednunder a multipath Rayleigh fading environment in a code-divisionnmultiple-access (CDMA) mobile system. An achievable SIR is defined asnthe maximum-minimum SIR among all users at a particular time step. Thencorresponding mobile transmission powers are denoted as the "optimumntransmission powers." In the individual power predictor (IPP) model, anlinear transversal filter is assigned to each user. The output of thenIPP, which is a linear combination of the optimum transmission powers ofnthe mobile during the current and previous power measurement periods,npredicts the optimum transmission power of the mobile in the next timenstep. In the global power predictor (GPP) model, a single predictor,nconstructed by a linear neural network, is used to predict the optimumntransmission powers of all mobiles in the next time step. In bothnpredictor models, the weights of the predictors are updated by using thenrecursive least squares algorithm. To further improve the performance, anreduced power-measurement period has been studied. Simulation resultsnshow that the proposed power control algorithm can achieve a lowernoutage probability and a smaller dynamic range of transmission powerncompared with a conventional power control scheme