## 1 Introduction  
Recently, attention has been directed towards visible light communication (VLC) systems, which have been indicated as having the potential for enhancing wireless communications using radio frequencies (RFs). The claim of high-speed wireless transmission has risen nowadays due to the limitations of radio frequencies. These limitations are due to spectrum determinations, unrestricted frequency bands, and open signal propagation [1]. Furthermore, the growing number of users led to considerable spectrum congestion in RF-based wireless telecommunication. In VLC, high-level frequency bands are used in visible light that belongs to the visible light spectrum, offering a new transmission medium compared to RF communication [1, 2]. VLC, which utilizes the visible light spectrum, can offer substantial impedance to electromagnetic interference and high transmission rates because of its bandwidth advantages. As a result, it has rapidly emerged as a prominent research topic in wireless communication [2]. Orthogonal frequency division multiplexing (OFDM) has been widely observed to be a groundbreaking source of knowledge that uses a number of orthogonal subcarriers to transfer data. OFDM presents several merits, including the use of the high-frequency spectrum and its impedance of multipath interference [3]. Despite its various advantages, OFDM has a bandwidth limitation due to its considerable out-of-band emissions, which cause spectral inefficiency [4]. Hence, a filtered OFDM scheme can handle this problem [5]. Recently, the layout and execution of employing OFDM in direct detection and intensity modulation (DD/IM) technology have been scrutinized in optical communications. The issue is that the signal power must be present in nonnegative and noncomplex amounts, but the OFDM baseband signal is present in nonreal and negative amounts [6; 7]. Regarding real signal production for intensity modulation in OFDM systems, two main approaches are typically used [8]. Firstly, the complex signal of the inverse fast Fourier transform (IFFT) output is passed through other converting processes to create a non-negative-valued signal. Despite the requirements of this technique and the need for additional hardware, like a digital-to-analog converter (DAC) and an in-phase and quadrature (IQ) mixer, the compensation of the carrier frequency equalizer may also be required for effective application [9]. The other technique for generating a real-valued signal in OFDM systems is harnessing the Hermitian symmetry (HS) limitation on the input datum at the IFFT. This technique permits the direct generation of a real-valued signal without the need for the additional hardware mentioned previously [9]. The HS constraint, often used in Discrete Multi-Tone (DMT) techniques, produces a real-valued signal that can be transmitted immediately via the optical channel [10; 11]. The HS algorithm allows a noncomplex OFDM signal to be generated by constraining the frequency symbols such that the input of the IFFT satisfies the HS constraint [12; 13]. The FFT and the reverse operation, the IFFT, together form the essentials of an OFDM system, and they play an important role in orthogonal subcarrier data modulation and demodulation [14]. Indeed, the desired length of the IFFT/FFT directly influences the OFDM transceiver power consumption, peak-average power ratio (PAPR), and chip size. While expanding the length of the IFFT/FFT, the complex multiplication and addition processes increase, leading to a higher power consumption. Additionally, the increased number of processing elements required for larger IFFT/FFT sizes may result in a larger occupied chip area, which can also increase the overall cost of the OFDM transceiver [14]. Furthermore, the HS constraint in optical OFDM schemes leads to doubled FFT/IFFT blocks. Specifically, using a \(2N\)-point subcarrier IFFT in the modulator results in an \(N\)-point subcarrier FFT at the demodulator.