LED non‐linearity mitigation techniques for optical OFDM‐based visible light communications

Sheu, Jeng-Shin; Li, Bing-Jia; Lain, Jenn-Kaie

doi:10.1049/iet-opt.2017.0059

Cited by 22 publications

(15 citation statements)

References 17 publications

(29 reference statements)

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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%

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%

BER Comparison and Enhancement of Different Optical OFDM for VLC

Hameed¹,

Abdulsatar²,

Sabri³

2021

IJIES

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“…As the first experimental verification, it was obtained the frequency response of the electric 5 The J1 jumper is kept closed to the polarization of the PD. April 26, 2019 DRAFT gain G E .…”

Section: B Proposed Experimental Setupmentioning

confidence: 99%

“…Another degrading factor are the nonlinearity issues [4]. The first source of nonlinearity occurs between the voltage applied to the HPLED and your current [5]. In [6] and [7],…”

Section: Introductionmentioning

confidence: 99%

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Predistortion and pre-equalization for nonlinearities and low-pass effect mitigation in OFDM-VLC systems

2019

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The orthogonal frequency division multiplexing (OFDM) transmission has shown promise in applications of visible light communication (VLC). However, the variation of the nonlinearity of the optical power emitted by the high power light emitting diode (HPLED) as a function of current and temperature implies in drastic OFDM-VLC performance degradation. The first part of this work, experimentally confirms and models this degradation due to temperature in a high power white HPLED. The higher attenuation at high frequencies, which is inherent to the HPLED and which is accentuated by the effect of the intrinsic capacitance of the photodiode, is another factor of degradation due to the reduction of the signal-to-noise ratio (SNR) at the receiver for such frequencies. For the mitigation of these effects, we propose a pre-distortion and digital preequalization scheme using a luminous feedback signal in the transmitter module. The system is modeled so that the operating points are mathematically deduced and evaluated by simulations and by an experimental setup. By allowing the linearization of the transmitted light signal and the maintenance of an average SNR in all OFDM subcarriers, the performance improvement is confirmed in comparison with other schemes, such as with non-predistortion, pre-distortion with fixed parameters, and simple post-equalization.

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“…Adaptive pre-distortion techniques was proposed in [7] using Wiener model consisting of a linear time-invarient and memoryless nonlinear model, greatly increasing the complexity of the VLC link, and was demonstrated by means of simulation only. For OFDM VLC links, a dynamic DC biasing and a look up table (LUT) based pre-distorter for mitigating the nonlinear effects was also proposed in [8], however this technique is extremely computationally intensive and once again has only been implemented in the simulation domain.…”

Section: Introductionmentioning

confidence: 99%

Investigation into Using Compensation for the Nonlinear Effects of the Output of LEDs in Visible Light Communication Systems

Burton

Ghassemlooy

Zvánovec

et al. 2019

2019 2nd West Asian Colloquium on Optical Wireless Communications (WACOWC)

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This paper investigate the effects of the nonlinear output power to the input current transfer function of a light emitting diode (LED) used as the transmitter in visible light communication systems, and proposes a compensation technique to mitigate the non-linearity. Using an off the shelf red, amber, blue, green (RAGB) LED the nonlinear transfer function is measured and then compensated for. The results show that, for the green LED, which has the highest degree of nonlinearity, an improvement in the received error vector magnitude (EVM) of almost 7 dB can be achieved. We also show that, the improvement in EVM over the uncompensated scheme decreases with increased LED linearity.

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LED non‐linearity mitigation techniques for optical OFDM‐based visible light communications

Cited by 22 publications

References 17 publications

BER Comparison and Enhancement of Different Optical OFDM for VLC

BER Comparison and Enhancement of Different Optical OFDM for VLC

Predistortion and pre-equalization for nonlinearities and low-pass effect mitigation in OFDM-VLC systems

Investigation into Using Compensation for the Nonlinear Effects of the Output of LEDs in Visible Light Communication Systems

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