A simple method for the analytical characterization of OFDM schemes with LINC transmitter structures

The linear amplification with nonlinear components (LINC) techniques allow a highly efficient amplification of orthogonal frequency division multiplexing (OFDM) signals, but also introduce nonlinear distortion. For this reason, it is important to study the impact of this distortion in the performance of OFDM schemes. Usually this impact is studied by taking advantage of the Gaussian nature of OFDM signals and using intermodulation products (IMP) tools. However, this approach suffers from complexity and/or even convergence problems especially when the nonlinearities are severe, as is the case LINC nonlinearities. In this work we define equivalent nonlinearities that can be employed to substitute the conventional LINC nonlinearities, but that lead to signals with the same spectral characterization. We then use these equivalent nonlinearities to provide accurate estimates for the power spectral density (PSD) and for the optimum performance of OFDM signals that are subjected to LINC structures.