Low Complexity Power Loading Strategies in OFDM-Based Transmission Systems

We consider the power loading strategies in OFDM-based systems that minimize the bit-error rate (BER) under the fixed transmit power (or equivalently minimize the transmit power under a fixed value of the bit-error rate). Aiming at a low implementation complexity of the transceiver and applicability of the derived algorithms to mobile systems, we consider sub-optimal techniques that are non-iterative and support transmission with a constant bit rate and fixed constellation size. Under such conditions, we derive a few sub-optimal power loading algorithms and assess their performances. The suggested methods improve the BER performance of an OFDM system in any radio channel. We show that in a Rayleigh environment the combinations of the derived power loading techniques with the recently proposed ordered subcarrier selection algorithm provide near optimal BER performance