Considerations on applying OFDM in a highly efficient power amplifier

A major obstacle in applying orthogonal frequency-division multiplexing (OFDM) in wireless local networks is the need for a highly linear and efficient radio frequency power amplifier. The strong fluctuated envelope of an OFDM signal makes it difficult to build this kind of power amplifier. In this paper, we consider the use of the envelope elimination and restoration method for OFDM power amplification and evaluate its performance tradeoffs. The results are compared to the performance of a linear power amplifier with different power backoffs. In addition, as the envelope of an OFDM signal is concentrated at low level, the average output power is low when a low supply voltage power amplifier is used. Simulation is done to show that the signal power (or signal-to-noise ratio for fixed noise level) can be traded off with clipping level for optimum bit-error-rate without increasing power supply voltage.