Blind Estimation of Memoryless AM/PM Nonlinearities in OFDM Systems

Nonlinear distortions by analog frontend components are becoming a growing problem. Not only do stringent linearity requirements that are crucial for modern modulation schemes like OFDM boost the costs in development and fabrication, but highly linear amplifiers are usually very energy inefficient. After looking at the theoretical and practical aspects of estimation of memoryless AM/AM nonlinearities, the focus of this paper is on AM/PM nonlinearities. First, we will derive the maximum likelihood estimator for a parameterized AM/PM nonlinearity. Then, we point out the complexity issues in practical implementations, propose suboptimal methods and compare them in terms of complexity and estimation performance.