الفهرس 
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Abstract
Visible light communication (VLC) technology gained a noticeable development interest at a worldwide scale as a reliable supplement to radiofrequency (RF) technology because of its ability to achieve additional merits, such as power consumption reduction, higher operating system rates, enhanced throughput, flicker-free operation, enhanced dimming control range and levels, and system complexity reduction. VLC technology is suitable for many applications, such as data localization, electro-magnetic interference (EMI) sensitive environments like aircraft, high speed-video streaming, traffic control systems, underwater data transmission, and internet of things (IoT) applications.
VLC transmitters and receivers are illumination devices that are enabled and modified for high-speed data transmission, based on simple intensity modulation/direct detection (IM/DD) techniques. However, these techniques’ performance decreases due to inter symbol interference (ISI), and their performance degrades severely at high data rates. Hence, utilizing multicarrier modulation (MCM) was introduced as a reliable solution to enhance system performance.
In this thesis, we present and study the peak-to-average power ratio (PAPR) problem for asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) and DC-biased optical - orthogonal frequency division multiplexing (DCO-OFDM). DCO-OFDM and ACO-OFDM with low peak-to-average power ratio performance become essential for practical VLC broadcasting systems due to non-linearity elimination. This work develops, simulates, and evaluates outstanding peak-to-average power ratio (PAPR) reduction strategies for visible light communication (VLC) broadcasting systems. The strategies of PAPR reduction are based on nonlinear companding techniques (NCT) and precoding techniques (PCT).
In this thesis, the types of NCT used to reduce PAPR are Rooting companding techniques (RCT), A-Law, µ-Law, and cos companding techniques. The discrete cosine transform (DCT), the discrete hartley transform (DHT), the walsh–hadamard transform (WHT), and the vander monde like matrix (VLM) transform are all examples of PCT that used to reduce the PAPR problem. We apply a combination between PCT and NCT on DCO-OFDM and ACO-OFDM.
The compatibility of ACO-OFDM schemes with practical applications is improved due to this research. The proposed µ-law companding technique combined with RCT achieved the best possible performance at companding factors ranging from 2 to 10. For instance, at RF = 0.5 (SQRT technique), the PAPR reduction value was 6.1 dB, while the 〖E_b/N_0 〗_diff was 1.1 dB. At µ=10 and RF=0.8, the PAPR reduction value was 7.7 dB and the 〖E_b/N_0 〗_diff was 2.3 dB. For A=5 and RF=0.6, the PAPR reduction value was 7.8 dB and the 〖E_b/N_0 〗_diff was 1.9 dB. The proposed µ-law companding technique merged with VLM at the companding factor from 2 to 15 achieved the optimum possible performance. For example, at µ=15, the PAPR reduction value was equal to 8.1 dB when the 〖E_b/N_0 〗_diff was 1.4 dB.