Joint Power Control in Cellular Radio Systems

— Transmitter power control has proven to be an efficient method to control interference and to improve spectrum utilization in cellular and personal communication systems. Previous results have shown that a significantly higher capacity may be reached, even if the system is subject to (practical) power constraints. Since in most cellular systems a duplex link is required, adequate transmission quality has to provided simultaneously in the down-and up-links. Previous results have shown that the same C/I is achievable in both the up-and down-links when transmitter powers are not limited. In this paper we investigate the properties and the performance of C/I-based power control schemes for the more realistic situation where such power constraints apply. The probability that a solution exists within the power constraints is derived by simulations. Results show that the probability that both up and down link are supported (duplex link) is not significantly lower than the probability that only an individual link (only up link or only down link) is supported.