Alleviation of LED nonlinearity impact in visible light communication using companding and predistortion

Lu, Huimin; Jin, Jianli; Wang, Jianping

doi:10.1049/iet-com.2018.5851

Cited by 13 publications

(5 citation statements)

References 20 publications

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“…The LED's non-linearity effects on the performance of VLC can be described using the LED V-I characteristic. Rapps model, which is commonly used in RF systems, is used to define the behavior of LED [17][18][19][20]26]. The LED model can be described as:…”

Section: Rapps Modelmentioning

confidence: 99%

“…The LED's transfer function results in non-linearity because of the cut-off region for Voltages below the turn-on value and distorts the maximum allowable signals [17]. The LED nonlinearity will impact the performance of VLC systems based on O-OFDM and lead to BER degrading [18][19][20]. Furthermore, many other influencing parameters affect BER performance, such as modulation order, Signal-to-Noise Ratio (SNR), channel types, and OFDM schemes [10,13,16,20,21].…”

Section: Introductionmentioning

confidence: 99%

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BER Comparison and Enhancement of Different Optical OFDM for VLC

Hameed¹,

Abdulsatar²,

Sabri³

2021

IJIES

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Visible Light Communication (VLC) becomes a promising technology in the Optical Wireless Communication OWC field. VLC has been developed based on Optical Orthogonal Frequency Division Multiplexing (O-OFDM) in recent years. The Bit Error Rate (BER) performance for various O-OFDM is studied in this paper. The non-linearity characteristic of Light-Emitting Diode (LED), modulation constellation size, O-OFDM scheme, and channel types impacts the BER performance of VLC systems significantly. The proposed model utilizes the conVolutional encoder of 2/3 rate and seven memory cells in the transmitter with O-OFDM for BER enhancement.At the receiver, the Viterbi algorithm system is employed with hard or soft-decision decoding. The proposed system is evaluated in Line-of-Sight and Non-Line-of-Sight (NLOS) channels. In the NLOS model, Zero Forcing Equalizer (ZFE) with channel estimation is added at the receiver path for equalizing the multipath diffused components. This study proves the capability of the proposed system in mitigating the LED non-linearity and reducing BER. The simulation results show the Signal-to-Noise Ratio (SNR) enhancement of the exanimated O-OFDM-based softdecision between 7 to 10 dB for the BER 10-5 in the LOS model, and for the NLOS model, the BER can be improved from 0.02 up to 10-5 at SNR 45dB.

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Section: Rapps Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

BER Comparison and Enhancement of Different Optical OFDM for VLC

Hameed¹,

Abdulsatar²,

Sabri³

2021

IJIES

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“…In general, the nonlinear effect of the LED and the dispersive effect of the optical multipath channel can be handled independently or jointly. Various schemes have been investigated to overcome the channel impairments in VLC systems, such as the peak to average power ratio (PAPR) reduction associated with the OFDM system [8][9][10][11][12], predistortion technique [13,14], nonlinear post-equalizer (NPE) scheme [15][16][17][18], and bit-interleaved coding [19], etc. Although the PAPR is easily implemented at the transmitter, the memory effect of LED is neglected, which degrades the system performance in high-speed transmission [11,12].…”

Section: Introductionmentioning

confidence: 99%

“…Although the PAPR is easily implemented at the transmitter, the memory effect of LED is neglected, which degrades the system performance in high-speed transmission [11,12]. The predistortion technique is an efficient way to mitigate the LED nonlinearity; however, the dispersive effect of the multipath VLC channel is not taken in account [13,14]. Thus, the specified equalizer should be employed at the receiver to maintain the overall performance, which inevitably increases the system cost.…”

Section: Introductionmentioning

confidence: 99%

Study of the Performance of Deep Learning-Based Channel Equalization for Indoor Visible Light Communication Systems

et al. 2021

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The inherent impairments of visible light communication (VLC) in terms of nonlinearity of light-emitting diode (LED) and the optical multipath restrict bit error rate (BER) performance. In this paper, a model-driven deep learning (DL) equalization scheme is proposed to deal with the severe channel impairments. By imitating the block-by-block signal processing block in orthogonal frequency division multiplexing (OFDM) communication, the proposed scheme employs two subnets to replace the signal demodulation module in traditional system for learning the channel nonlinearity and the symbol de-mapping relationship from the training data. In addition, the conventional solution and algorithm are also incorporated into the system architecture to accelerate the convergence speed. After an efficient training, the distorted symbols can be implicitly equalized into the binary bits directly. The results demonstrate that the proposed scheme can address the overall channel impairments efficiently and can recover the original symbols with better BER performance. Moreover, it can still work robustly when the system is complicated by serious distortions and interference, which demonstrates the superiority and validity of the proposed scheme in channel equalization.

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“…For the first approach, the nonlinear power-current curve of the LED is first estimated, which is then used to compensate the LED nonlinearity. In [18][19][20], transmitter-side LED nonlinearity estimation and compensation, i.e., pre-distortion, has been considered. In [21,22], receiver-side LED nonlinearity estimation and compensation, i.e., post-distortion, has been applied.…”

mentioning

confidence: 99%

LED Nonlinearity Estimation and Compensation in VLC Systems Using Probabilistic Bayesian Learning

et al. 2019

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In this paper, we propose and evaluate a novel light-emitting diode (LED) nonlinearity estimation and compensation scheme using probabilistic Bayesian learning (PBL) for spectral-efficient visible light communication (VLC) systems. The nonlinear power-current curve of the LED transmitter can be accurately estimated by exploiting PBL regression and hence the adverse effect of LED nonlinearity can be efficiently compensated. Simulation results show that, in a 80-Mbit/s orthogonal frequency division multiplexing (OFDM)-based nonlinear VLC system, comparable bit-error rate (BER) performance can be achieved by the conventional time domain averaging (TDA)-based LED nonlinearity mitigation scheme with totally 20 training symbols (TSs) and the proposed PBL-based scheme with only a single TS. Therefore, compared with the conventional TDA scheme, the proposed PBL-based scheme can substantially reduce the required training overhead and hence greatly improve the overall spectral efficiency of bandlimited VLC systems. It is also shown that the PBL-based LED nonlinearity estimation and compensation scheme is computational efficient for the implementation in practical VLC systems.

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Alleviation of LED nonlinearity impact in visible light communication using companding and predistortion

Cited by 13 publications

References 20 publications

BER Comparison and Enhancement of Different Optical OFDM for VLC

BER Comparison and Enhancement of Different Optical OFDM for VLC

Study of the Performance of Deep Learning-Based Channel Equalization for Indoor Visible Light Communication Systems

LED Nonlinearity Estimation and Compensation in VLC Systems Using Probabilistic Bayesian Learning

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