Extended Spatial-Index LED Modulation for Optical MIMO-OFDM Wireless Communication

An efficient optical modulation technique for multi-input multi-output (MIMO) orthogonal frequency division multiplexing (OFDM) visible light communication system is proposed in this paper. The proposed modulation technique is termed as extended spatial-index light-emitting diode (LED) modulation. In the proposed technique, the indices (the spatial domain) of the LEDs are exploited in a dynamic style to not only get rid of the optical OFDM time-domain ( OFDM t d ) shaping problem but also to expand the LED indices spatial modulation domain. The indices of the active LEDs in the proposed technique are changed from the two LEDs active situation to the situation where all or several LEDs are active. Moreover, within the selected active LED indices, the power weight distribution and the positions of the OFDM components are varied to expand the resultant spatial domain. Therefore, the proposed technique offers a considerable spectral efficiency improvement over the up-to-date LED index OFDM modulation schemes even with a lower number of LEDs. The key idea of the proposed technique is to maximize the LEDs’ indices spatial position (spatial domain) utilization, where both the power weight allocation and the positions of the complex OFDM time domain components are varying several times over the same active LED indices combination, which improve the optical system spectral efficiency. The simulation results asserted the superiority of the proposed technique, as it improves both the average bit error rate (ABER) and the achievable data rate (R) compared with existing up-to-date OFDM-LED index modulations with even lower computational complexity.

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Optical orthogonal frequency division multiplexing using frequency/time domain filtering for high spectral efficiency up to 1 bit/s/Hz

Optical Fiber Communication Conference and Exhibit ◽

10.1109/ofc.2002.1036444 ◽

2003 ◽

Cited By ~ 34

Author(s):

H. Sanjoh ◽

E. Yamada ◽

Y. Yoshikuni

Keyword(s):

Time Domain ◽

Spectral Efficiency ◽

Orthogonal Frequency Division Multiplexing ◽

Frequency Division Multiplexing ◽

Frequency Division ◽

High Spectral Efficiency

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

Applied Sciences ◽

10.3390/app9132711 ◽

2019 ◽

Vol 9 (13) ◽

pp. 2711 ◽

Cited By ~ 2

Author(s):

Chen Chen ◽

Xiong Deng ◽

Yanbing Yang ◽

Pengfei Du ◽

Helin Yang ◽

...

Keyword(s):

Orthogonal Frequency Division Multiplexing ◽

Bayesian Learning ◽

Light Emitting Diode ◽

Visible Light Communication ◽

Compensation Scheme ◽

Light Emitting ◽

Current Curve ◽

Time Domain Averaging ◽

Nonlinearity Estimation ◽

Led Nonlinearity

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

Photonics ◽

10.3390/photonics8100453 ◽

2021 ◽

Vol 8 (10) ◽

pp. 453

Author(s):

Pu Miao ◽

Weibang Yin ◽

Hui Peng ◽

Yu Yao

Keyword(s):

Deep Learning ◽

Visible Light ◽

Communication Systems ◽

Orthogonal Frequency Division Multiplexing ◽

Light Emitting Diode ◽

Visible Light Communication ◽

Channel Equalization ◽

Training Data ◽

Traditional System ◽

Ber Performance

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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A Novel Transceiver Model for Polar Transform Optical (PTO-) OFDM for Visible Light Communication (VLC) Based on Peak to Average Power Ratio Reduction using Precoding

International Journal of Innovative Technology and Exploring Engineering - Special Issue ◽

10.35940/ijitee.e9914.0891020 ◽

2020 ◽

Vol 9 (10) ◽

pp. 307-315

Keyword(s):

Visible Light ◽

Power Efficiency ◽

Orthogonal Frequency Division Multiplexing ◽

Light Emitting Diode ◽

Average Power ◽

Visible Light Communication ◽

Intensity Modulation ◽

Power Ratio ◽

Positive Real ◽

High Data

Indoor visible light communication (VLC) has the potential of providing high data rates for short-range wireless communication with a relative spatial elevated security in contrast to a radiofrequency wireless one. To support that high data stream, Orthogonal Frequency Division Multiplexing (OFDM) is used; however, due to the limited operational bandwidth of the commercial white light-emitting diode (LED), signal processing techniques are used to increase the efficiency of the OFDM and to adapt OFDM to VLC systems. As a major concern, the intensity modulation direct detection necessary for VLC requires positive real signal, this is dealt with by imposing Hermitian pre-possessing or Cartesian to polar conversion post-processing to the OFDM. The use of the Cartesian to polar converter allows the transmission of complex OFDM symbols through the intensity modulation channel. A polar transform optical (PTO-) OFDM presented here as an improvement and simplification of previous polar optical OFDM schemes gives an efficient transceiver architecture. Nevertheless, both OFDM transmission techniques for Visible optical links, similar to radiofrequency (RF), suffer greatly from irregular excessive Peak-to-Average power ratio (PAPR). Higher PAPR reduces the power efficiency of the On-Off Keying (OOK) based on pulse amplitude modulation (PAM). Furthermore, it also is recommendable to reduce the PAPR for conformity with eye safety. A precoding technique is proposed to reduce the PAPR of intensity-modulated for direct detectability of the OFDM signal destined for the wireless optical link using Cartesian-to-Polar conversion. Based on the enhanced processing at the front ends and using MATLAB simulation, it is proven that the presented model can improve the link parameters including the bit error rate (BER) and signal to noise ratio (SNR) and bandwidth efficient compared to Hermitian modified ones.

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OFDM-Based Generalized Optical MIMO

10.36227/techrxiv.13270751 ◽

2020 ◽

Author(s):

Chen Chen ◽

Xin Zhong ◽

Shu Fu ◽

Xin Jian ◽

Min Liu ◽

...

Keyword(s):

Frequency Domain ◽

Time Domain ◽

Orthogonal Frequency Division Multiplexing ◽

Direct Detection ◽

Multiple Input Multiple Output ◽

Detection Algorithm ◽

Spatial Multiplexing ◽

Spatial Modulation ◽

Input Multiple Output ◽

The Time Domain

<p>The combination of multiple-input multiple-output (MIMO) transmission and orthogonal frequency division multiplexing (OFDM) modulation has been shown to be an effective way to substantially enhance the capacity of bandlimited optical wireless communication (OWC) systems. In this paper, we propose four OFDM-based generalized optical MIMO techniques for intensity modulation/direct detection (IM/DD) OWC systems, including OFDM-based frequency-domain generalized spatial modulation (FD-GSM), frequency-domain generalized spatial multiplexing (FD-GSMP), time-domain generalized spatial modulation (TD-GSM) and time-domain generalized spatial multiplexing (TD-GSMP). For OFDM-based FD-GSM and FDGSMP, spatial mapping is performed in the frequency domain, while it is carried out in the time domain for OFDM-based TDGSM and TD-GSMP. To efficiently estimate both spatial and constellation symbols in each OFDM-based generalized optical MIMO technique, a corresponding maximum-likelihood (ML) detection algorithm is designed. Extensive simulations are conducted to evaluate and compare the performance of the proposed four OFDM-based generalized optical MIMO techniques in a typical indoor environment. Simulation results demonstrate the superiority of OFDM-based TD-GSM and TD-GSMP for various spectral efficiencies of 4, 5 and 6 bits/s/Hz, when a relatively high secondary direct current (DC) bias is adopted.</p>

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Deep Learning-Assisted Index Estimator for Generalized LED Index Modulation OFDM in Visible Light Communication

Photonics ◽

10.3390/photonics8050168 ◽

2021 ◽

Vol 8 (5) ◽

pp. 168

Author(s):

Manh Le-Tran ◽

Sunghwan Kim

Keyword(s):

Deep Learning ◽

Visible Light ◽

Error Rate ◽

Orthogonal Frequency Division Multiplexing ◽

Light Emitting Diode ◽

Visible Light Communication ◽

Ofdm System ◽

Signal Demodulation ◽

Index Estimation ◽

Index Modulation

In this letter, we present the first attempt of active light-emitting diode (LED) indexes estimating for the generalized LED index modulation optical orthogonal frequency-division multiplexing (GLIM-OFDM) in visible light communication (VLC) system by using deep learning (DL). Instead of directly estimating the transmitted binary bit sequence with DL, the active LEDs at the transmitter are estimated to maintain acceptable complexity and improve the performance gain compared with those of previously proposed receivers. Particularly, a novel DL-based estimator termed index estimator-based deep neural network (IE-DNN) is proposed, which can employ three different DNN structures with fully connected layers (FCL) or convolution layers (CL) to recover the indexes of active LEDs in a GLIM-OFDM system. By using the received signal dataset generated in simulations, the IE-DNN is first trained offline to minimize the index error rate (IER); subsequently, the trained model is deployed for the active LED index estimation and signal demodulation of the GLIM-OFDM system. The simulation results show that the IE-DNN significantly improves the IER and bit error rate (BER) compared with those of conventional detectors with acceptable run time.

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A multilayers adaptive ALACO-OFDM for spectral efficiency improvement using PSO algorithm in visible light communication systems

Journal of Optical Communications ◽

10.1515/joc-2020-0236 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Aymen Abdalmunam Hameed ◽

Anuar Mat Safar ◽

Junita Nordin ◽

Montadar Abas ◽

Norizan Nawawi

Keyword(s):

Visible Light ◽

Spectral Efficiency ◽

Communication Systems ◽

Orthogonal Frequency Division Multiplexing ◽

Electrical Power ◽

Visible Light Communication ◽

Pso Algorithm ◽

Efficiency Improvement ◽

Frequency Division ◽

Simulation Results

AbstractIn this paper, we propose a new adaptive layered asymmetrically-clipped optical orthogonal frequency division multiplexing (ALACO-OFDM) technique as a method to improve the spectral efficiency of optical system, especially visible light communication (VLC). Particle swarm optimisation (PSO)-based LACO-OFDM method is used for this purpose and the channel capacities are studied. Simulations using variable layers are carried out to validate the theoretical steps. The simulation results indicate that the ALACO-OFDM technique has significantly improve the spectral efficiency compared to previous techniques such as ACO-OFDM. Moreover, it is shown that channel capacities of different layers are significantly improved when electrical power is increased.

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Performance Analysis of ACO-OFDM NOMA for VLC Communication

10.21203/rs.3.rs-1006678/v1 ◽

2021 ◽

Author(s):

Jayashree Pradhan ◽

Pratiksha Holey ◽

Vinod Kiran Kappala ◽

Santos Kumar Das

Keyword(s):

Interference Cancellation ◽

Orthogonal Frequency Division Multiplexing ◽

Light Emitting Diode ◽

Visible Light Communication ◽

Optical Signal ◽

Electrical Signal ◽

Frequency Division Multiplexing ◽

Frequency Division ◽

Positive Signal ◽

Power Domain

Abstract Visible light communication (VLC) is seeking a lot of attention in the recent years due to high bandwidth, low cost, ease of implementation. VLC can be used for illumination as well as communication at the same time. Light emitting diode (LED) acts as a transmitter for data transmission and photo detector is used at the receiver side. Intensity Modulation (IM) is used to convert electrical signal into optical signal where only real and positive signal need to be transmitted. Optical orthogonal frequency division multiplexing (O-OFDM) is used in the VLC to enhance the bandwidth limitation due to LED. Using OOFDM for VLC does not provide the massive connectivity in an multi-user environment. A Non orthogonal multiple access (NOMA) is the further expansion where user can use both the time and frequency resources but distinguished in power domain with successive interference cancellation (SIC) at the receiver to decode the signal of each user. Also, Asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) is used to get positive signal with enhanced spectral efficiency. The proposed method is evaluated analytically and using simulation in terms of bit error rate (BER).

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Experimental Investigation of Zadoff-Chu Matrix Precoding for Visible Light Communication System with OFDM Modulation

Advances in Condensed Matter Physics ◽

10.1155/2018/5173285 ◽

2018 ◽

Vol 2018 ◽

pp. 1-6

Author(s):

Xinyue Guo ◽

Yang Guo ◽

Shuangshuang Li

Keyword(s):

Visible Light ◽

Orthogonal Frequency Division Multiplexing ◽

High Speed ◽

Forward Error Correction ◽

Signal To Noise Ratio ◽

Light Emitting Diode ◽

Average Power ◽

Visible Light Communication ◽

Potential Candidate ◽

Ofdm Modulation

Light-emitting diode- (LED-) based visible light communication (VLC) has become a potential candidate for next generation high-speed indoor wireless communication. Due to the limited modulation bandwidth of the LED, orthogonal frequency division multiplexing (OFDM) modulation is particularly preferred in the VLC system to overcome the ISI, which suffers from the high peak-to-average power ratio (PAPR) and leads to severe performance loss. In this paper, we propose and experimentally demonstrate a novel Zadoff-Chu matrix (ZCM) precoding scheme, which can not only reduce the PAPR, but also provide uniform signal-to-noise ratio (SNR) profile. The theoretical analysis and simulation show that the proposed scheme achieves better PAPR performance compared with the traditional precoding schemes. The experimental demonstration further validates the bit error rate (BER) performance improvement, where the measured BERs are all below the 7% pre-forward error correction (pre-FEC) limit of 3.8 × 10−3 when the transmitted data rate is 50 Mb/s.

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