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Abstract The Optical Wireless Communications (OWC) has seen rapid development during recent years. This gro wing popularity is due to several characteristics of the considerable importance of the consumer electronics products, such as large bandwidth that is also not having spectrum regulations imposed, low cost, and license free operation. The visible light com munication (VLC) systems have their own unique advantages, with several new technologies, products and patents . They have been developed during the end of last century . Especially in indoor environments, VLC could enable wireless home networking systems w hich offload data traffic from existing RF systems. VLC systems employ intensity modulation (IM) and direct detection (DD) of the optical carrier. White LEDs (Light Emitting Diodes) in VLC is an emerging technology that required current research so it can eventually be used for common communications systems. LEDs have a numbe r of advantages, one of which its long life time . However, like many emerging technologies, VLC has many technical issues that need to be addressed. This thesis proposes a VLC system f or indoor application. T he objective of this work reduce s the peak - to - average power ratio (PAPR) and achieves acceptable bit error rate (BER) performance for indoor use. The proposed tech niques were evaluated through computer simulations. Orthogonal Frequ ency Division Multiplexing (OFDM) is used with visible light communication (VLC) systems to reduce the effects of the inter - symbol interference (ISI) and to achieve communication with high speed of data transmission using huge bandwidth. However, OFDM base d VLC systems suffer from high peak - to - average power ratios (PAPRs)The work can be divided into three main parts. The first part gives a detailed overview of the OWC, VLC and OFDM system. This is followed by an overview of the PAPR problem in the multic arrier systems. The second part proposes hybrid PAPR reduction technique based on signal transformation combined with clipping. The Hadamard transform is used in the proposed technique to reduce the PAPR without affecting the bit error rate (BER) of the VL C systems. The optimum clipping threshold at which the PAPR is reduced simultaneously with the improvement the BER of the VLC systems is also determined. The performance of the proposed system is evaluated in terms of the Complementary Cumulative Distribut ion Function (CCDF) and the BER. The Third part proposes an OFDM structure based on using the discrete cosine transform (DCT) precoding before using the Inverse Fast Fourier Transform (IFFT) stage with clipping to further reduce the PAPR and the BER. The Partial Transmit Sequence (PTS) strategy was modified to reduce the PAPR of the OFDM signal in the VLC system. PTS was appropriate for transmission in the VLC system and which is combined with the continuous phase modulation (CPM) based OFDM (CPM - OFDM) sys tem to reduce the PAPR of the optical OFDM signal. |