Performance evaluation and total degradation of 16-QAM modulations over satellite channels

The paper presents the total degradation (TD) performance of five 16-QAM constellations versus the input back off (IBO) of a high power amplifier (HPA) for a nonlinear satellite communication system. Results show that TD performance gives a set of convex curves and the star (4, 12) 16-QAM constellation has the lowest TD among the five 16-QAM constellations. The optimum IBO for each constellation is also calculated. Finally, the symbol error rate (SER) comparison of the five 16-QAM constellations is presented when they work in linear and nonlinear environments. For the nonlinear environment case, the HPA is forced to work with optimum IBO for each constellation. Results indicate that while star (5, 11) and rectangular 16-QAM are the best constellations in the linear case, star (4, 12) 16-QAM is the best one in the nonlinear case.