Symbol error rate calculation and data pre‐distortion for 16‐QAM transmission over nonlinear memoryless satellite channels

Abstract

This paper presents a simplified mathematical approach to evaluate the performance of any given circular constellation of 16-level quadrature amplitude modulation (16-QAM) in terms of symbol error rate (SER). Following this approach, with the aim to work with memoryless nonlinear satellite channels, a model is derived as a generalized form for both linear and nonlinear channels in the presence of down link additive white Gaussian noise (AWGN). The analysis provides means to calculate the optimal ring ratio (RR) and phase difference (PD) for several possible candidates of 16-QAM circular constellations. The effects of RR and PD on the SER performance are investigated in the analysis. To overcome the nonlinear distortion, data pre-distortion is taken into account in the study. The paper gives a general procedure for data pre-distortion implementation for all circular 16-QAM constellations. The analytical formulation has been extended for total degradation (TD) performance measure as a function of input back-off (IBO) of the nonlinear amplifier. A SER performance-comparison between different constellations for 16-QAM systems has also been presented in this paper. The analytical results are validated by simulation.

The Nonlinearities of Memoryless Power Amplifier and Model of Predistorter

“…Since more linear PAs are less efficient, practitioners may wish to use the PA in a configuration that allows for maximum PA efficiency while still stay below the spectral emission limits. [2] Among all techniques, digital baseband predistortion is one of the most cost effective, [3] and generally, we often gain the model of PA by data calculation and then use the PA model to realize the predistortion.…”