The huge bandwidth and immunity to electromagnetic interference make visible light communication (VLC) systems the preferred technique for many applications. Unfortunately, the superposition of multiple subcarriers in VLC orthogonal frequency division multiplexing systems leads to a high peak-to-average power ratio (PAPR). So, in this study, we aim to reduce PAPR in VLC systems and improve the system performance by proposing non-distorting PAPR reduction techniques like precoding techniques as it doesn’t affect the system data rate because they do not require any obligatory transmission of side information. Moreover, it has a very good ability to reduce the PAPR without affecting the system BER performance. So, different precoding reduction techniques are proposed like discrete cosine transform (DCT), discrete sine transform (DST), discrete Hatley transform (DHT), and Vandermonde like matrix (VLM), to address the high PAPR and light-emitting diode-restricted linear range problems in VLC systems. The proposed technique using DHT, DCT, DST, and VLM provided a significant advantage in reducing the PAPR by 1.35 dB, 1.46 dB, 2.12 dB, and 2.17 dB, respectively. So the proposed technique is based on using the VLM precoding technique to achieve maximum reachable PAPR reduction value. Also, a comparison of the presented work and related literature reviews for PAPR reduction techniques are held to ensure the validity and effectiveness of the proposed scheme.

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. In this article, the authors enhance the data rate, system complexity, power efficiency, and spectrum efficiency in VLC systems. An innovative unipolar transceiver system is proposed, mathematically analyzed, and compared with other existing techniques and it demonstrates to have a very high data rate ratio (43.75%) with a good system bit energy to noise ratio (E_b/N_o) compared to other existing techniques. Development for the traditional asymmetrically and symmetrically clipping optical (ASCO-OFDM) system is also proposed, which involves combining a modified receiver with the ASCO-OFDM system traditional transmitter. The proposed receiver reduces the system complexity by O (N log₂ N) with better E_b/N_o than the conventional ASCO-OFDM. Detailed analysis, simulation results, and comparison of the proposed systems with the existing systems are presented beside a brief assessment of existing techniques.

Peak to average power ratio (PAPR) is a great issue in multicarrier systems especially in the LTE/LTEA communication system, so there is still a wide range that handles the PAPR problem. Orthogonal frequency division multiple access (OFDMA) technique is used in the downlink LTE system as it has many advantages over multipath propagation system. On the other side it suffers from a high PAPR that will affect the energy efficiency. In this paper, a new hybrid scheme is proposed in the downlink mobile communication system to overcome this issue. Besides reducing the PAPR, the proposed scheme did not have a significant increase in the system complexity but also it had nearly the same bit error rate (BER) system performance as OFDM system. Also we introduce a combination of different pre-coding techniques in OFDM system that improve the BER such as (Discrete Hartley Transform, Discrete Cosine Transform and Discrete Sine Transform) with the companding techniques that have a good ability in reducing the PAPR with a little increase in system complexity such as (Absolute exponential, Tangent rooting and Logarithmic) companding techniques. We tested the system performance for different techniques combination, and according to the analysis and the simulations done, it was found that the hybrid technique that is composed from the Discrete Hartley transform pre-coding technique and the Logarithmic companding technique in the downlink system outperforms all other hybrid techniques combinations.

Rapid advancements in 5G and the internet of things (IoT) have significantly increased global mobile network traffic as they require very high bandwidth. Consequently, there is growing interest in alternative communication technologies like visible light communication (VLC) that has a vast bandwidth in addition to the advantage of low implementation costs, and more secure system, since it achieves high immunity to electromagnetic interference, which is a very needed requirement in IoT. But despite all these advantages, VLC faces challenges like high peak-to-average power ratio (PAPR) that results from the superposition of transmitted peaks of several subcarriers. PAPR is considered one of the high-priority issues, especially in the VLC systems, as we always aim to keep the LED working within its linear range to prevent LED damage or burn. So, This paper studied, simulated, and designed a proposed optical modulation scheme named precoding Flip-OFDM (PF-OFDM), to mitigate this issue in VLC systems by suggesting a PAPR precoding reduction scheme like discrete sine transform (DST), and discrete cosine transform (DCT), while evaluating the system BER. The proposed PF-OFDM substantially reduces PAPR without compromising the system BER performance as it requires energy per bit to noise ratio at BER= $$\:{10}^{-4}\:$$ of 15, 19.2, 24, 29, and 34.4 dB at modulation orders of 16, 64, 256, 1024, and 4096-QAM, which is nearly the same as the traditional Flip-OFDM. Moreover, the PF-OFDM employing DST demonstrates substantial improvements by comparing it with FLIP-OFDM as it reduces the PAPR by approximately 3.25 dB, 2.96 dB, 2.73 dB, 2.85 dB, and 2.58 dB at modulation orders of 16, 64, 256, 512, and 1024-QAM, respectively. Moreover, a comparison between PF-OFDM and other state-of-the-art techniques in the literature is provided to validate the effectiveness of the proposed approach.