Increasing the power efficiency of an IEEE802.11a power amplifier

OFDM modulation is extensively used in many applications. However, it also exhibits high peak-to-average power ratios (PAPR) requiring the associated transmit amplifier to have a very large linear region. This linear amplifier does therefore have poor power efficiency. To reduce the PAPR, cupping and filtering was carried out at baseband. This paper investigates the impact that clipping has on the resultant power efficiency and BER. The simulations show that when the input back-off (IBO) dynamically controls the input average power in every OFDM symbol, for a 64-subcarrier QPSK OFDM signal, the power efficiency can be improved by 55% without increasing the bit error rate.