Performance Analysis of Low-Complexity Uniform Power Loading with Reduced-Overhead OFDM Systems over Rayleigh Fading Channels

In this paper, we analyze the performance of two low-complexity uniform power loading with reduced- overhead orthogonal frequency division multiplexing (OFDM) schemes over Rayleigh fading channels. In the first feedback scheme, the receiver feeds back to the transmitter the channel gains and the indices of the best $M$ subchannels; while for the second feedback scheme, the receiver feeds back only the indices of the best $M$ subchannels. In both schemes, the available power budget is equally distributed over the best $M$ subchannels. We derive closed-form expressions for the capacity and the outage capacity of the first and second schemes, respectively. Numerical results show that there is an optimal number of the best subchannels, $M$, that maximizes the achievable capacity and it depends on the system parameters.