Uplink Power Control for Next Generation Mobile Broadband Wireless Access Systems: System-Level Simulation Results

In uplink OFDM/A systems that support link adaptation, e.g., via adaptive modulation and coding (AMC), and/or HARQ schemes, there have been suggestions that fast, closed-loop power control (PC) may not be necessary. It might be sufficient to use open-loop, slow power control method as a countermeasure to the effects of slow fading, i.e., propagation path loss and shadow fading. Here we will compare the performance of uplink open-loop, closed-loop power control with a fixed SINR target or AMC, based on some simulation results. Although it is necessary to emphasize the high throughput aspect of the technology evolution, the support of various traffic types that require medium to low data rates, e.g., VoIP and video conferencing applications should not be overlooked. As transmission at high power often introduces additional interference to users in the other sectors or cells, and increases battery power consumption, the user terminal (UT) should only transmit at the minimum required power to support the data rate as required by the application. We will show that in a typical cellular environment, closed-loop power control can be used to limit the UT's transmit power. This leads to a longer battery life and lower intercell interference.