الفهرس 
Theoretical Background for VLC Optical Modulation Techniques
Simulation Model and Parameters for the Proposed SchemesOnly 14 pages are availabe for public view
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Abstract
Visible Light Communications (VLC) are receiving increased attention in the wireless communications research community. VLC is secured, power efficient, and operates in the visible light range, thus RF communication bandwidth limitation is overcome. The huge bandwidth and immunity to electromagnetic interference makes VLC systems the preferred technique for many applications such as underwater data transmission, internet of things (IoT) applications, and traffic control systems. In VLC the data is transmitted by modulating the input current intensity of the LED. Based on this idea, different optical modulation techniques were introduced for optical wireless communication (OWC). But, to get high data rate transmission with low inter-symbol interference (ISI), optical orthogonal frequency division multiplexing (OFDM) was proposed to be utilized in VLC systems. However, the superposition of multiple subcarriers in VLC OFDM systems leads to a high peak-to-average power ratio (PAPR). In this thesis, the overall aggregated throughput, data rate, system complexity, power efficiency, and spectrum efficiency in VLC systems are enhanced by promoting three new innovative optical modulation techniques titled the Special Symmetric and Asymmetric Clipping Optical OFDM (SSACO-OFDM), the Enhanced Asymmetrically and Symmetrically Clipping Optical OFDM (E-ASCO OFDM), and the Improved Aggregated Rate for Optical OFDM (IARO-OFDM) systems. Moreover, to make the proposed systems practically VLC broadcasting systems, a study of the PAPR problem with different PAPR precoding reduction techniques (PRT) are proposed to get a power efficient system and enhance the VLC system performance. So, different PRT are proposed like discrete cosine, discrete sine, discrete Hartley Transforms, and Vandermonde-like matrix, to address the high PAPR and light-emitting diode restricted linear range problems in the EASCO-OFDM, and IARO-OFDM VLC proposed systems. Also, a detailed analysis, comparison, and simulation results of the presented work with the related literature reviews are held to ensure the validity and effectiveness of the proposed schemes besides an assessment of existing techniques.