Adaptive power loading with BER-constraint for OFDM systems

A novel adaptive power loading algorithm with the constraint of target overall bit error rate (BER) for orthogonal frequency division multiplexing (OFDM) systems is proposed in this article. The proposed algorithm aims to minimize the required transmit power with fixed data rate and uniform (nonadaptive) bit allocation, while guaranteeing the target overall BER. The power loading is based on the unequal-BER (UBER) strategy that allows unequal mean BERs on different subcarriers. The closed-form expressions for optimal BER and power distributions are derived in this article. Simulation results indicate the superiority of the proposed algorithm in terms of BER performance and algorithmic complexity.