Uplink Power Control for an OFDMA Mobile Cellular System

In this paper, we will investigate the effects of uplink closed-loop power control in a mobile cellular system that employs OFDMA multiple access for the uplink. Analytical results are derived to compare open-loop with closed-loop power control approaches. Furthermore, system-level simulation results modeling multi-users in a multi-cell deployment scenario will also be discussed. The analytical results show the condition under which the open-loop approach for transmit power control may become unstable, leading to increases in transmit power levels with no improvement in the level of signal to interference and noise ratio (SINR) achieved. Simulation results have also indicated that closed-loop power control is more effective in enhancing throughput performance of users at the cell edge. The simulation models the effects of adaptive modulation coding (AMC) by including multiple SINR targets for the closed-loop power control. Closed-loop power control can be effective in supporting user applications that require medium to low data rates, using transmit power levels that are just sufficient for the desired applications, while avoiding the creation of high levels of intercell interference.