Digital Predistortion of Wideband Satellite Communication Signals with Reduced Observational Bandwidth and Reduced Model Order Complexity

Abstract

The increase in the demand for wireless communications from the user-end point of view calls for an infrastructure that is constantly more capable, reliable and efficient. One of the critical nodes in the telecommunications process, from the hardware perspective, is the power amplifier (PA): it is not only the more powerconsuming device in the transmission chain but it also has a highly nonlinear behaviour which can compromise the well-functioning of the communications infrastructure. This thesis addresses the digital predistortion (DPD) technique, whose goal is to reduce the nonlinear influence of the PA in the transmitted signal, and enhances it with two contributions which can allow for a bigger computational and economic efficiency without compromising the effectiveness of DPD. These contributions are the Reduced Observational Bandwidth and the Reduced Model Order. In the former, the observational path required for the implementation of the DPD is redesigned to permit the capture of wideband signals using multiple reduced bandwidth observations. The latter, on the other hand, aims at reducing the number of coefficients needed for DPD by discarding the less contributive modes of the PA behavioural model. Additionally, the technique of reducing the signal PAPR is applied in order to seek a more effective predistortion. The experimental campaign in a real DUT proved that the reduction of the observational bandwidth was feasible and produced similar results when compared to a full spectrum observation.