The future fleets of high throughput satellites (HTS) aim to support a diverse set of applications ranging from "connecting the unconnected" to "video on demand" at ultra-high data rates. However, achieving such ultra-high data rates has pushed for the need of more flexible and efficient payloads. Bandwidth and power efficient transponders require a multicarrier signal excitation of the on-board high power amplifiers (HPAs), and an operating point closer to saturation. However, this leads to severe linear and non-linear distortions due to the increased inter-carrier-interference (ICI) and intermodulation (IMD) noise, resulting in an overall degradation of system performance. The analog linearizers built into the channel amplifiers of the on-board HPAs offer only limited gain and are non-adaptive. In addition, the latest digital video broadcasting (DVB-S2X) standard is pushing for uplink signals with bandwidths that are more or less equal to that of transponder’s input multiplexer (IMUX) and output multiplexer (OMUX). This introduces severe linear and non-linear distortions, especially for the carriers at the edges. Equalizers are proposed at the receiver terminal to compensate for the aforementioned distortions, but they increase the complexity of the receiver significantly. Due to the recent advancements in on-board processors (OBPs), the distortions caused by the HPAs and transponder filters can be mitigated on-board the satellite by employing linearization techniques such as digital predistortion (DPD) while maintaining a high degree of power and bandwidth efficiency. Therefore, this work focuses on the on-board predistortion methods and proposes the “on-board, adaptive, bandlimited, signal, memory polynomial”-based DPD as the best suited predistortion method for HTS. Bandlimited DPD allows for the use of low sampling rate converters in OBPs resulting in low power consumption. This work presents a novel iterative direct learning architecture (DLA)-based bandlimited memory polynomial (MP) DPD, and compares its performance against a state-of-the-art in-direct learning architecture (IDLA)-based bandlimited MP DPD. The novel DLA-based DPD approach outperforms the IDLA-based DPD, especially under severe bandlimitation constraints. More importantly, using the proposed DPD methods, this thesis also presents the results of a thorough investigation made to identify the system parameters which should be optimized for the best DPD performance. In addition, the presented system parameter identification analysis also highlights the scenarios where it is feasible to implement DPD. Lastly, the thesis also discusses and presents the gains of implementing the proposed novel DLA-based DPD in multiport amplifiers (MPA) and 5G waveforms.    «

The future fleets of high throughput satellites (HTS) aim to support a diverse set of applications ranging from "connecting the unconnected" to "video on demand" at ultra-high data rates. However, achieving such ultra-high data rates has pushed for the need of more flexible and efficient payloads. Bandwidth and power efficient transponders require a multicarrier signal excitation of the on-board high power amplifiers (HPAs), and an operating point closer to saturation. However, this leads to sev...    »