Joint bit-loading and power-allocation for OFDM systems based on statistical frequency-domain fading model

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Abstract
Orthogonal frequency division multiplexing (OFDM) modulation scheme is adopted by more and more wireless communication systems to help achieve reliable high-rate data transmission over multipath fading channels. We obtain the subcarrier fading statistics of OFDM systems operating in frequency-selective fading channels with arbitrary Rician fading parameters and inter-path correlation. This analysis leads to the discovery of practical OFDM channels with dissimilar subcarrier fading statistics. Based on the subcarrier-level statistical information, we propose an statistical bit-loading and power-allocation algorithm to maximize the overall spectral efficiency and minimize the transmission power requirement of the OFDM system while maintaining curtain target bit error rate (BER) level. Unlike its existing counterparts, our proposed algorithm adapts the transmission parameters based on the OFDM subcarrier fading statistics rather than on the instantaneous channel conditions. Results show that the proposed scheme can achieve considerable performance enhancement over non-adaptive systems.