An adjustable fuzzy power control architecture for a multi-rate WCDMA system

Abstract

This paper describes an adjustable fuzzy power control architecture for a multi-rate WCDMA system. The adjustable fuzzy power control architecture is employed to adaptively control the transmission power and select the suitable transmission rate in the uplink transmission. Unlike the conventional power control mechanisms, the proposed power control architecture can dynamically adjust the membership function of the fuzzy system by the input signal-to-interference (SIR) error and the error change. The adjustment of the membership function can improve the system performance in a time-varying fading channel. In addition, the conventional Lagrangian relaxation method and the fuzzy power control architecture with fixed membership function were evaluated by computer simulations. According to the simulation results, the adjustable fuzzy power control architecture achieves a smaller outage probability and has a higher average transmission rate than those of the prior power control architectures in a wireless fading channel.

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“…At present, the outer loop power control method of 30 system can be categorized into fixed step-size method (FSM), adaptive step-size method (ASM) [4] and the method based on fuzzy logic (FLM) [5][6].…”

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“…At present, the outer loop power control method can be divided into fixed step-size method(FSM), adaptive step-size method (ASM) [4] and the method based on fuzzy logic (FLM) [5][6][7]. As for adjustment step-size value, there is a contradiction between control accuracy and response speed in FSM.…”