Design and Linearization of Energy Efficiency Power Amplifier in Nonlinear OFDM Transmitter for LTE-5G Applications. Simulation and measurements of energy efficiency power amplifier in the presence of nonlinear OFDM transmitter system and digital predistortion based on Hammerstein-Wiener method

This research work has made an effort to understand a novel line of radio frequency power amplifiers (RFPAs) that address initiatives for efficiency enhancement and linearity compensation to harmonize the fifth generation (5G) campaign. The objective is to enhance the performance of an orthogonal frequency division multiplexing-long term evolution (OFDM-LTE) transmitter by reducing the nonlinear distortion of the RFPA. The first part of this work explores the design and implementation of 15.5 W class AB RF power amplifier, adopting a balanced technique to stimulate efficiency enhancement and redeeming exhibition of excessive power in the transmitter. Consequently, this work goes beyond improving efficiency over a linear RF power amplifier design; in which a comprehensive investigation on the fundamental and harmonic components of class F RF power amplifier using a load-pull approach to realise an optimum load impedance and the matching network is presented. The frequency bandwidth for both amplifiers was allocated to operate in the 2.620-2.690 GHz of mobile LTE applications. The second part explores the development of the behavioural model for the class AB power amplifier. A particular novel, Hammerstein-Wiener based model is proposed to describe the dynamic nonlinear behaviour of the power amplifier. The RF power amplifier nonlinear distortion is approximated using a new linear parameter approximation approach. The first and second-order Hammerstein-Wiener using the Normalised Least Mean Square Error (NLMSE) algorithm is used with the aim of easing the complexity of filtering process during linear memory cancellation. Moreover, an enhanced adaptive Wiener model is proposed to explore the nonlinear memory effect in the system. The proposed approach is able to balance between convergence speed and high-level accuracy when compared with behavioural modelling algorithms that are more complex in computation. Finally, the adaptive predistorter technique is implemented and verified in the OFDM transceiver test-bed. The results were compared against the computed one from MATLAB simulation for OFDM and 5G modulation transmitters. The results have confirmed the reliability of the model and the effectiveness of the proposed predistorter.Fundacão para a Ciência e a Tecnologia, Portugal, under European Union’s Horizon 2020 research and innovation programme ... grant agreement H2020-MSCA-ITN- 2016 SECRET-722424 I also acknowledge the role of the National Space Research and Development Agency (NASRDA) Sokoto State Government Petroleum Technology Trust Fund (PTDF

Implementation of a VLC HDTV Distribution System for Consumer Premises

A unidirectional, visible light communication (VLC) system intended for the distribution of Digital Video Broadcasting (DVB), high-definition television (HDTV) content to DVB compatible TVs within consumer premises is presented. The system receives off-air HDTV content through a consumer grade DVB-T/T2 terrestrial set-top-box (STB) and re-encodes its Moving Picture Experts Group (MPEG) transport stream (TS) using a pulse position modulation (PPM) scheme called inversion offset PPM (IOPPM). The re-encoded TS is used to intensity modulate (IM) a blue light-emitting diode (LED) operating at a wavelength of 470 nm. Directed line-of-sight (DLOS) transmission is used over a free-space optical (FSO) channel exhibiting a Gaussian impulse response. A direct-detection (DD) receiver is used to detect the transmitted IOPPM stream, which is then decoded to recover the original MPEG TS. A STB supporting a high-definition multimedia interface (HDMI) is used to decode the MPEG TS and enable connectivity to an HD monitor. The system is presented as a complementary or an alternative distribution system to existing Wi-Fi and power-line technologies. VLC connectivity is promoted as a safer, securer, unlicensed and unregulated approach. The system is intended to enable TV manufacturers to reduce costs by, firstly, relocating the TV’s region specific radio frequency (RF) tuner and demodulator blocks to an external STB capable of supporting DVB reception standards, and, secondly, by eliminating all input and output connectors interfaces from the TV. Given the current trend for consumers to wall-mount TVs, the elimination of all connector interfaces, except the power cable, makes mounting simpler and easier. The operation of the final system was verified using real-world, off-air broadcast DVB-T/T2 channels supporting HDTV content. A serial optical transmission at a frequency of 66 MHz was achieved. The system also achieved 60 Mbit/s, error free transmission over a distance of 1.2 m without using error correction techniques. The methodology used to realise the system was a top-down, modular approach. Results were obtained from electrical modelling, simulation and experimental techniques, and using time-domain and FFT based measurements and analysis. The modular approach was adopted to enable design, development and testing of the subsystems independently of the overall system