Impact of HPA Non-Linearities and Predistortion Techniques in LDM Satellite Systems

This paper analyzes the impact of the non-linearities of satellite high power amplifiers (HPAs) on the gain achievable by power domain non-orthogonal multiplexing techniques in Direct-to-Home (DTH) satellite services. Previous studies proposed a system that combines DVB-S2X and Layered Division Multiplexing (LDM), providing significant capacity gains compared with traditional Time Division Multiplexing approaches. The paper investigates various use cases with a different mixture of broadcast and point-to-point/point-to-multipoint service scenarios. The satellite HPA non-linear characteristic is modeled using the Saleh model, and the benefit of including pre-correction techniques is examined with simulations. The results show a relevant reduction of the gain provided by LDM with simpler non-linearity models. Furthermore, the benefit of pre-correction schemes is also remarkable and keeps capacity gains close to 30% in certain use cases.