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 language | English |
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Pages (from-to) | 210-220 |
Number of pages | 11 |
Journal | IEICE Transactions on Communications |
Volume | E85-B |
Issue number | 1 |
Publication status | Published - 2002 Jan |
Keywords
- Adaptive control
- CDMA
- Minimum variance control
- Power control
ASJC Scopus subject areas
- Software
- Computer Networks and Communications
- Electrical and Electronic Engineering