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This paper proposes a new receiver based on frequency-domain diversity combining (FDDC) for an asymmetrically clipped optical orthogonal frequency-division multiplexing (ACO-OFDM) system. Compared with its time-domain diversity combining (TDDC) counterpart, the FDDC receiver is capable of more effectively exploiting the frequency selectivity of the...
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Orthogonal Frequency Division Multiplexing (OFDM) is typically a system used in encoding digital data. It has huge benefits among which primary are high spectral efficiency upon Inter Symbol Interference (ISI) and robustness. It also has some drawbacks, the main hitch in OFDM system is High Peak to Average Power Ratio (PAPR). In order to minimize P...
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... are the samples after the Decision Process (DP). Also, there are different types of decision processes as in [23][24][25], however, the ML algorithm can be classified as a simpler process than other decision methods with a good BER enhancement. In our study, we assume the traditional ACO-OFDM system decision process is ML for a fair comparison with our proposed systems. ...
... Since complexity is a critical factor for O-OFDM systems and reducing PAPR always comes at a cost [16], we calculate the (2Nlog 2 N). Moreover, the proposed μ-NCT+MoRoC method provides N/(2log 2 N) times lower complexity than the existing different RX design techniques [24] and [28]. It can be concluded that without increasing the complexity, the proposed μ-NCT+MoRoC method can achieve significant PAPR enhancement than other compared methods that do not use side information. ...
... This information is utilized by the diversity combining (DC) technique (Chen et al. 2009) to improve the BER performance of ACO-OFDM signal. This technique is commonly applied to receiver known as Time-Domain Diversity Combining Receiver (TDDR) (Dang et al. 2015;Li et al. 2019). This was applied at each layer of LACO-OFDM to further enhance its BER performance as demonstrated in (Mohammed et al. 2017). ...
... ACO-TDDR OFDM and ACO-TDDC OFDM demonstrates a 3 dB improvement over conventional ACO-OFDM. Similarly, 2-LACO-TDDR OFDM and 2-LACO-TDDC OFDM demonstrate a 3dB improvement over conven- The complexity 'Θ' of a system is defined by the number of complex multiplications of IFFT/FFT operations (Dang et al. 2015;Niwareeba et al. 2021). The computational complexity comparison of ACO-TDDR and ACO-TDDC was analyzed for ACO-OFDM (single layer), as shown in Table 1. ...
This paper demonstrates the advantage of application of time domain diversity combining (TDDC) at the transmitter over the time domain diversity combining receiver (TDDR) for a single layer of ACO-OFDM in terms of reduced complexity. The paper further demonstrates the implementation of time domain delay-and-advanced operation with TDDC at the transmitter for a two-layered LACO-OFDM system, where all the subcarriers are utilized and an improved BER performance is achieved. The new improved 2-LACO-OFDM system achieves 2.7 dB, 3.3 dB and 3.7dB better optical signal to noise ratio (OSNR) than the ACO-TDDC, 2-LACO-TDDC, 3-LACO-TDDC respectively.
... This information is utilized by the diversity combining (DC) technique [9] to improve the BER performance of ACO-OFDM signal. This technique is commonly applied to receiver known as Time-Domain Diversity Combining Receiver (TDDR) [10,11]. This was applied at each layer of LACO-OFDM to further enhance its BER performance as demonstrated in [12]. ...
This paper discusses the implementation of time domain delay-and-advanced operation with diversity combining at the transmitter for a two-layered LACO-OFDM system. This technique utilizes all the subcarriers and improves the BER performance. The new improved 2-LACO-OFDM system achieves 2.7 dB, 3.3 dB and 3.7dB better optical signal to noise ratio (OSNR) than the ACO-TDDC, 2-LACO-TDDC, 3-LACO-TDDC respectively.
... The diversity combining receiver is able to overcome the DC offsets noise [9], [10]. The combining can be also performed in frequency domain [11]. The SNR gain of 1.5∼2.7 dB for 7% forward error correction (FEC) limit will be achieved for ACO-OFDM [12]. ...
An iterative pairwise maximum likelihood (ML) receiver is proposed for asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) in visible light communications (VLC). With the aid of the pairwise ML detection, half of the received ACO-OFDM samples are forced to zero in time domain. However, when the signal-to-noise ratio (SNR) is low, the pairwise ML detection may cause misjudgment. With the iterative pairwise ML detection, the ACO-OFDM symbols are detected in frequency domain and the SNR gain of 3dB could be available. Simulation results show that the pairwise ML receiver without iteration provides the SNR improvement of 1.5~2.7 dB for 7% forward error correction (FEC) limit. The proposed iterative receiver gives a SNR gain of 2.6~2.9 dB with 7% FEC limit.
... J. Dang (2015) et al. presented that, this paper define a new receiver based on frequency-domain diversity combining (FDDC) for an asymmetrically clipped optical orthogonal frequency-division multiplexing (ACO-OFDM) system. compare with its TDDC the counterpart, FDDC receiver is competent of more efficiently exploit frequency selectivity of channel to additionally get better the performance of detection, which proved by the post combining signal to noise ratio also called (SNR) analysis. ...
... With a enough number of applicant symbol vector sets, eFDDC receiver still outperforms a type of iterative receiver, which is well-known to have the superior presentation in current literature, yet the complexity of eFDDC is lower due to the avoidance of matrix inversion. Those facts recommend that the FDDC and the eFDDC receivers are tough receiver candidate for ACO-OFDM system [14]. ...
The field of visible light communication (VLC) has diverse applications to the end user including streaming audio, video, high-speed data browsing, voice over internet and online gaming. This comprehensive textbook discusses fundamental aspects, research activities and modulation techniques in the field of VLC. Visible Light Communication: A Comprehensive Theory and Applications with MATLAB®_discusses topics including line of sight (LOS) propagation model, non-line of sight (NLOS) propagation model, carrier less amplitude and phase modulation, multiple-input-multiple-output (MIMO), non-linearities of optical sources, orthogonal frequency-division multiple access, non-orthogonal multiple access and single-carrier frequency-division multiple access in depth. Primarily written for senior undergraduate and graduate students in the field of electronics and communication engineering for courses on optical wireless communication and VLC, this book: Provides_up-to-date literature in the field of_VLC, Presents MATLAB codes and simulations to help readers understand simulations, Discusses applications of VLC in enabling vehicle to vehicle (V2V) communication, Covers topics including radio frequency (RF) based wireless communications and_VLC, Presents modulation formats along with the derivations of probability of error expressions pertaining to different variants of optical OFDM. é 2022 Taylor and Francis Group, LLC.
We propose a superposition based light emitting diode (LED) nonlinearity mitigation scheme for asymmetrically clipped optical-orthogonal frequency division multiplexing (ACO-OFDM) optical wireless communications (OWC) systems, where a non-redundant signal stream is superimposed with an ACO-OFDM source signal stream, requiring no pilot and no side information. Based on the anti-symmetry property that a non-redundant signal and its symmetric signal is equal to zero with the same absolute value, a non-redundant signal is used to reduce the large amplitude of the ACO-OFDM signal and enhance its symmetric ACO-OFDM signal that is clipped to zero due to negative signal clipping, allowing LED nonlinearity mitigation. The proposed scheme is also energy-efficient, as the large-amplitude signal reduction is equal to the symmetric signal enhancement, requiring no extra power. However, the designed non-redundant signals fall on odd subcarriers and interfere with source signals. The even subcarriers include the absolute value of source signals, which can be utilized to recover source signals. The polarity of source signals on even subcarriers can be determined by ensuring that the remaining part is higher than the clipping part of the large-amplitude signal in the process of LED nonlinearity mitigation. Simulation results show that the proposed scheme outperforms a number of state-of-the-art methods in the literature as well as ACO-OFDM systems with no LED nonlinearity mitigation in terms of bit error rate (BER).
A new diversity combining receiver is proposed for asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM). With the aid of symmetry recovering the odd and even signals of ACO-OFDM are distinguished directly in time domain without complex operation such as inverse fast Fourier transform (IFFT). Simulation results show that the diversity combining receiver we proposed gives a signal-to-noise ratio (SNR) improvement of 2∼3 dB. The receiver proposed also has the same SNR gain as the conventional diversity combining receiver distinguishing the odd and even signals in frequency domain.
