Throughput improvement and PAPR reduction for OFDM-based VLC systems using an integrated STC-IMADJS technique

Abstract

Visible light communication (VLC) is a technology that is currently being employed to achieve high data rates. Orthogonal frequency division multiplexing (OFDM) is a powerful scheme for intensity modulation and direct detection (IM-DD) that is becoming increasingly important. OFDM systems based on VLC are accomplished through the implementation of IM-DD constraints, including direct current biased optical OFDM (DCO-OFDM), asymmetrically clipped optical OFDM (ACO-OFDM), and asymmetrically clipped DC-biased (ADO-OFDM), among others. The OFDM technique based on VLC is inefficient in terms of spectral efficiency and has a high peak to average power ratio (PAPR). In this article, the symbol time compression-image adjust (STC-IMADJS) technique will be proposed for throughput maximization and PAPR reduction in the DCO-OFDM, ACO-OFDM, and ADO-OFDM systems. Furthermore, the STC technique enables the simultaneous transmission of two sub-carriers through Walsh spreading codes without inference between them. As a result, the OFDM symbol has been reduced by 50%. The IMADJS strategy reduces the high PAPR of transmitted signals by compressing large signals and expanding small signals, as long as the average power level remains constant after compression. Therefore, the proposed STC-IMADJS technique doubles the throughput as well as significantly reduces the PAPR for OFDM systems based on VLC. The simulation results are performed using Matlab-2021a for 1024 sub-carriers. As a result, the simulation results show that the proposed technique reduces the PAPR by 3.7 dB ($$86\%$$ 86 % ), 8.16 dB ($$93\%$$ 93 % ), and 1.81 dB ($$20\%$$ 20 % ) for DCO-OFDM, ACO-OFDM, and ADO-OFDM systems respectively. Furthermore, the technique has a significantly lower computational complexity than conventional OFDM systems based on VLC. Finally, the measures of performance through this article are bit error rate and complementary cumulative distribution function.

An ADO‐OFDM with integrated precoding, companding and optimized power allocation methods for high‐speed data transmission in visible light communication

“…Mohamed et al 26 STC-IMADJS based ADO-OFDM was developed Using Walsh spreading codes, the STC allows simultaneous transmission of two subcarriers without interference. By compressing and expanding large and small signals, the IMADJS method lowers the PAPR of transmitted signals.…”

“…In order to decrease PAPR and increase throughput in VLC‐OFDM, Mohamed et al 26 designed an ADO‐OFDM. A symbol time compression‐image adjustment (STC‐IMADJS) method is developed to address these limitations in ADO‐OFDM systems.…”

An effective technique for increasing capacity and improving bandwidth in 5G narrow-band internet of things

“…The Hadamard matrix represents a different Walsh code and each row or column of this matrix represents a different Walsh code. The two spreading Walsh codes are given as (3) [24]:…”

Doubling the Number of Connected Devices in Narrow-band Internet of Things while Maintaining System Performance: An STC-based Approach

“…The STC-OFDM was initially presented as a wireless approach in [31], which was proven to have similar results to OFDM while saving 50% of bandwidth by compressing OFDM symbols by half. In particular, the STC technique uses a spreading and combining mechanism in the transmitter and a symbol time extension (STE) approach in the receiver to expand the received symbol [32], as shown in Figure 4. First, the transmitted bits are converted into the polar forms b 0 and b 1 .…”