Performance of comparison metrics on M-QAM OFDM systems with high power amplifier

Orthogonal frequency division multiplexing (OFDM) has been adopted by several wireless transmission standards. A major drawback of OFDM is the large dynamic range of the transmit waveforms, making OFDM vulnerable to nonlinearities of the power amplifier (PA) and causing the PA to yield low power efficiency on the RF to dc power conversion. A commonly used performance metric to characterize a dynamic range of OFDM signal is the peak-to-average power ratio (PAPR). To suppress the nonlinear effects, one may want to reduce the PAPR value. However, this results in the increase of error vector magnitude (EVM) and decrease of modulation error ratio (MER). EVM and MER analysis is useful tool for prediction of dynamic performance. In this paper, we compare among the different performance metrics such as EVM and MER and show that they can be equivalently useful as signal to noise ratio(SNR) and bit error rate(BER). Simulation results are shown to illustrate the performance of EVM and MER based on these relationships. Simulation result shows that by modulating a signal at fixed subcarriers, the MER increases and EVM decreases.