Analysis of distributed discrete power control

Transmitter power control has been proven to be an efficient method to control cochannel interference in cellular PCS, and to increase bandwidth utilization. Most previous studies have assumed that the transmitter power level is controlled in a continuous range. In practice, however, power levels are assigned from a discrete set. We analyze the difference between the optimal continuous power vector and the optimal discrete one employing the method of round off error analysis in digital computation. M. Andersin et al. (Wireless Pers. Commun., vol.6, no.3, 1998) conclude that, by simply "discretizing" the continuous power control algorithm, the resulting distributed discrete power control (DDPC) algorithm may oscillate, which results in a poorer link quality. We present two improved ceiling DDPC algorithms, and, with a simple example, it is shown that the proposed algorithms alleviate oscillation.