Analytical evaluation of nonlinear distortion effects on OFDMA signals used in the downlink transmission

In this paper we consider the evaluation of nonlinear distortion effects on the downlink transmission of systems employing OFDMA (orthogonal frequency division multiple access) signals. Our results allow an analytical spectral characterization of the transmitted signals, as well as the computation of nonlinear interference levels on the received signals. It is shown that the set of subcarriers allocated to each user and the corresponding power have a key impact on the nonlinear distortion effects. It is also shown that nonlinear distortion levels are lower when just a small fraction of the subcarriers is used (i.e., when the system load is small).