Proportional power control algorithm for time varying link gains in cellular radio systems

Thus far, most of the power control (PC) algorithms derived from numerical algebra envisage a system where the link gains are fixed, and the PC command can take any value in the real field. These two assumptions are quite unrealistic in actual communication systems, since link gains are time varying and PC commands must be sent over capacity limited channels. Most of the power control algorithms derived from control theory, on the other hand, analyze the PC problem from the point of view of one link. In this paper, we propose a fully distributed and nonlinearly proportional PC algorithm for time-varying link gain environments that can possibly be implemented also as a 1-bit increase/decrease PC command, and analyze it from system point of view. We construct a simple direct bridge between the link gain changes and the parameters of the proposed algorithm. It is shown that the proposed algorithm drives the carrier-to-interference+noise+ratio (CIR) to an interval in time-changing link gain environments. Simulation results for urban speeds show that the proposed algorithm is more robust against link gain changes as compared to the linear distributed PC algorithm of Foschini and Miljanic as a reference algorithm. The proposed algorithm was also verified with an advanced dynamic system simulator.