Investigation of the discrete trigonometric transformation techniques in vlc

In this thesis, an investigation is primarily undertaken into real-based DTT transforms that serve to reduce system complexity by eliminating the Hermitian symmetry requirement within the conventional DFT-based OFDM structure. The novel methods introduced in this study, derived from the combination of DTT transforms (DCT/DST), demonstrate the feasibility of concurrently transmitting distinct information through separate LED light sources over the same frequency-selective channel. Moreover, these methods exhibit greater efficiency in terms of computational complexity when compared to traditional OFDM and FOFDM techniques. They enable the utilization of single-tap equalization, thereby enhancing PAPR performance without compromising BER performance. Additionally, it is demonstrated that the transformation matrices employed in the proposed methods can be utilized for pre-coding PAPR reduction, yielding markedly superior PAPR performance in comparison to conventional DCT pre-coding and other hybridized DCT pre-coding methods documented in the literature. Finally, an analysis of these proposed pre-coding matrices is conducted in conjunction with a suggested approach to replace Hermitian symmetry for generating real-valued symbols within the conventional DFT-OFDM structure. This analysis is then compared with DCT pre-coding and hybridized pre-coding methods, revealing that the DCT/DST(4) pre-coding method offers significantly improved PAPR performance with reduced computational complexity, without a substantial impact on BER performance.