Visible Light Communication (VLC) systems are favoured for numerous applications due to their extensive bandwidth and resilience to electromagnetic interference. This study delineates various constructions of Optical Orthogonal Frequency Division Multiplexing (O-OFDM) approaches employed in VLC systems. Various factors are elaborated within this context to ascertain a more effective O-OFDM approach, including constellation size, data arrangement and spectral efficiency, power efficiency, computational complexity, bit error rate (BER), and peak-to-average power ratio (PAPR). This paper seeks to assess these approaches’ BER and PAPR performance across varying modulation orders. Regrettably, in VLC systems based on OFDM methodology, the superposition of multiple subcarriers results in a high PAPR. Therefore, this study aims to diminish the PAPR in VLC systems, enhancing system performance. We propose a non-distorting PAPR reduction technique, namely the Vandermonde-Like Matrix (VLM) precoding technique. The suggested technique is implemented across various O-OFDM approaches, including DCO-OFDM, ADO-OFDM, ACO-OFDM, FLIP-OFDM, ASCO-OFDM, and LACO-OFDM. Notably, this method does not affect the system’s data rate because it does not require the mandatory transmission of side information. Furthermore, this technique can decrease the PAPR without impacting the system’s BER performance. This study compares the proposed PAPR reduction technique against established methods documented in the literature to evaluate their efficacy and validity rigorously.

One of the primary challenges faced by visible light communication (VLC) systems employing optical orthogonal frequency division multiplexing is the peak-to-average power ratio (PAPR). This study is dedicated to designing, simulating, and evaluating bit error rate (BER) and PAPR reduction methods tailored for the VLC broadcasting system. The asymmetric clipped optical orthogonal frequency division multiplexing (ACO-OFDM) scheme is highlighted in this work for its impressive performance. Therefore, the proposed PAPR mitigation methodologies applied to ACO-OFDM. The proposed PAPR reduction strategy involves 5 distinct precoding methodologies. The PAPR was mitigated by 3.485 dB after applying the DST precoding methodology. Still, the WHT precoding methodology can achieve PAPR reduction by 1.131 dB, without BER performance degradation, with respect to the conventional ACO-OFDM system. Furthermore, the work addresses another challenge in VLC systems: the bit error rate (BER). This is accomplished by introducing approaches to Time Domain Noise Cancelation and Frequency Domain Noise Cancelation (FDNC). The BER performance of these 2 receiver models is nearly the same. The simulation results indicate the system performance enhancement after applying noise cancellation approaches by 1.65 dB at the 4-QAM modulation scheme and 2.97 dB at the 1024-QAM modulation scheme. The 16-QAM modulation scheme, after applying DST and WHT methodologies alongside noise cancellation approaches, can enhance both PAPR by 20.83% and 6.76%, but the E_b/N₀ performance enhancement by 10.10% and 14.64%, respectively. Additionally, the effectiveness and validity of the proposed schemes are verified by comparing them with relevant literature reviews on PAPR reduction techniques and selecting an optimal choice among them.

Visible Light Communications (VLC) is a promising communication technology designed to serve as a supplemental system to radio frequency communications for many demanding applications. VLC employs optical orthogonal frequency division multiplexing (O-OFDM) techniques to achieve higher data rates and resist intersymbol interference. Among these, asymmetrically clipped O-OFDM (ACO-OFDM) stands out as one of the most power-efficient and high-performing methods for VLC. However, like other O-OFDM techniques, ACO-OFDM encounters the challenge of a high peak-to-average power ratio (PAPR). VLC utilizes light-emitting diodes (LEDs) for data transmission at the transmitter and photodiodes (PDs) for data reception at the receiver. However, the high PAPR issue can drive LEDs to operate in their nonlinear region, reducing system performance and potentially causing LED damage or burnout. The paper aims to alleviate the high PAPR issue by proposing a hybrid combination of precoding technique and various nonlinear companding techniques. Compared to the standard ACO-OFDM, the proposed methodologies can reduce the PAPR issue by 5.5796 dB without a bit error rate (BER) degradation. The paper also aims to improve another aspect of the BER performance of ACO-OFDM. The paper proposes two noise cancellation receiver models to enhance the performance by 2.275 dB compared to standard ACO-OFDM to attain the same BER performance. The proposed PAPR reduction methodology with noise cancellation receiver model can achieve PAPR reduction by 6.0057 dB and enhanced performance by -0.309 dB to achieve the BER performance relative to standard ACO-OFDM. This paper systematically evaluates the proposed PAPR reduction approach by comparing it with established methods from the literature, ensuring a comprehensive assessment of its effectiveness and reliability.

In modern telecommunication systems the channel bandwidth and the quality of the reconstructed decoded audio signals are considered as major telecommunication resources. New speech or audio coders must be carefully designed and implemented to meet these requirements. EVS and OPUS audio coders are new coders which used to improve the quality of the reconstructed audio signal at different output bitrates. These coders can operate with different input signal type. The performance of these coders must be evaluated in terms of the quality of the reconstructed signals. The MOS and the PEAQ evaluation methods are nominated in this paper to examine the quality of these output decoded signals. The quality evaluation test achieved by using clean record signals (noise free) for individual oriental and orchestral instruments. These evaluation methods proved that the EVS and OPUS audio coders provide high audio quality for various categories of musical instruments. The OPUS has the highest encoding quality than the EVS for different musical instruments at different output bitrates.