Adaptive minimum-variance closed-loop power control in CDMA cellular systems

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8 Citations (Scopus)

Abstract

This paper introduces a new application of adaptive control theory to power control in a code division multiple access (CDMA) cellular system operating over mobile fading radio channels. Conventional feedback power control algorithms allow the base station to send a power command to either raise or lower each user's transmission power according to a bang-bang-like control policy. In this paper, we present an adaptive minimum-variance power control methodology which can be shown to improve power control performance consistently against a random nature of the near-far effect, shadowing and fast varying fading. Two adaptive implementations are considered: direct and indirect control. In the indirect adaptive control, a minimum-variance controller is combined with a constrained estimation algorithm to ensure the stability of a link gain model. In the direct adaptive control, the controller parameters are obtained directly from a standard estimation algorithm. Our simulations have shown that the proposed adaptive minimum-variance power control schemes provide much smaller error variance than the conventional fixed-step bang-bang control scheme and consequently the reverse channel capacity of the CDMA system can be significantly increased.

Original languageEnglish
Pages (from-to)210-220
Number of pages11
JournalIEICE Transactions on Communications
VolumeE85-B
Issue number1
Publication statusPublished - 2002 Jan

Keywords

  • Adaptive control
  • CDMA
  • Minimum variance control
  • Power control

ASJC Scopus subject areas

  • Software
  • Computer Networks and Communications
  • Electrical and Electronic Engineering

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