Power control in cellular mobile radio systems

Abstract

Recently, the number of cellular phone users has drastically increased. The frequency band assigned for the use of mobile cellular phone is an important limited resource for communication. There have been many studies to increase the capacity of the cellular radio systems. Transmitter power control is a part of them. In cellular systems, transmitter power is regulated by power control algorithms to provide each user an acceptable connection by limiting the interference seen by other users. This thesis is concerned with three topics of power control. First, an efficient power control scheme is developed. In this scheme, the power control is performed at each base by using some parameters. The algebraic property of its CIR balancing algorithm is analyzed. The scheme proposes a quick method for obtaining a least upper bound on the achievable CIR. The proposed scheme is also considered in a cellular system with positive receiver noise. With the proposed algorithm, the CIRs are balanced sufficiently in a short power control period. Next, a fading estimation for reverse link closed-loop power control in CDMA systems is proposed. Most efficient power control algorithms are based on perfect propagation gain estimation. However, it is necessary to estimate the propagation gain for correct power control. Among the factors which comprise the propagation gain, the rayleigh fading is the most difficult one to estimate. The thesis deals with the problem of rayleigh fading estimation. A simple and effective estimation method is proposed. The estimation method employs exponential smoothing and adapts to the mobile speed. The capacity of a CDMA system can be significantly increased with the proposed method when compared with conventional methods. Finally, a call admission control algorithm in CDMA cellular systems is proposed. Call admission control is very important especially in CDMA cellular systems to enhance the spectrum efficiency. The thesis introduces a call admissio...