Low‐frequency nonlinear memory effects in M‐ary QAM communications systems

Abstract

AbstractThis article focuses on low‐frequency nonlinear memory effects caused by a power amplifier (PA). Two models have been adopted for the PA to perform simulations of an M‐ary communications system, the memory polynomial model and a dynamic Volterra‐based model, both were able to predict the desired effects. An experimental setup allowing the identification of the coefficients using time‐domain data acquisitions has been used, with the capability to represent the distorted signal in the constellation plane and to make error vector magnitude measurements. A good agreement between simulations with the adopted models and measurements has been obtained, showing the degradation of the communications system due to low‐frequency nonlinear memory effects. A significant distortion and Eb/No losses are observed when a symbol rate of 17 ksym/s (low frequency zone) is used, when compared with the behavior of the system at 2 Msym/s. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:826–829, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26608