Minimum-BER Power Allocation for Multicarrier Systems with Outdated Channel State Information

Multicarrier transmission systems can effectively exploit the frequency selectiveness of wireless multipath fading channels. With the perfect knowledge of the channel state information (CSI) at the transmitter, the spectral efficiency and/or link reliability of multicarrier systems can be further improved with proper power or bit loading. In this paper, we examine the effect of outdated CSI on the performance of power allocation schemes that target at minimizing the system BER. Based on a well-established correlation model between the feedbacked subchannel gains and the actual subchannel gains, we evaluate the performance loss of i) power allocation solely based on the outdated CSI and ii) power allocation based on outdated CSI as well as the outdatedness of CSI cases.