Experiments in Non-Line-of-Sight Li-Fi Channels

Mana, Sreelal Maravanchery; Hellwig, Peter; Hilt, J. Zach; Berenguer, Pablo Wilke; Jungnickel, Volker

doi:10.1109/glc.2019.8864131

Cited by 23 publications

(25 citation statements)

References 10 publications

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“…A standard Agilent vector network analyzer (VNA E5061B3L5) is connected between Tx and Rx feeding a continuous wave signal with variable frequency from 1 to 200 MHz. For characterizing each channel, the optical frontend response is calibrated out, which is measured at a minimum distortion-free distance in free LOS [6]. All the channel responses and channel parameters are calculated as given in [6].…”

Section: Introductionmentioning

confidence: 99%

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LiFi Experiments in a Hospital

Mana¹,

Hellwig²,

Hilt³

et al. 2020

Optical Fiber Communication Conference (OFC) 2020

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Section: Introductionmentioning

confidence: 99%

“…For characterizing each channel, the optical frontend response is calibrated out, which is measured at a minimum distortion-free distance in free LOS [6]. All the channel responses and channel parameters are calculated as given in [6].…”

Section: Introductionmentioning

confidence: 99%

LiFi Experiments in a Hospital

Mana¹,

Hellwig²,

Hilt³

et al. 2020

Optical Fiber Communication Conference (OFC) 2020

Self Cite

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show abstract

“…The other reason is that the coherence bandwidth of a tpicyal indoor non-LOS (NLOS) channel is much higher than the LED’s 3-dB bandwidth, thus making the LED capable of approximately representing the frequency response of the entire VLC system. Recent experimental results have shown that a maximum root mean-square (RMS) delay spread of 14.2 ns was measured for a 3 m NLOS link in a worst practical indoor scenario [ 39 , 40 ]. The coherence bandwidth can be estimated to be in the order of several tens of MHz, which is still much higher than the LED panel’s bandwidth of 1.4 MHz that was used in this work.…”

Section: Methodsmentioning

confidence: 99%

A 40 Mb/s VLC System Reusing an Existing Large LED Panel in an Indoor Office Environment

Ghassemlooy

Zvánovec

et al. 2021

Sensors

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With advances in solid-state lighting, visible light communication (VLC) has emerged as a promising technology to enhance existing light-emitting diode (LED)-based lighting infrastructure by adding data communication capabilities to the illumination functionality. The last decade has witnessed the evolution of the VLC concept through global standardisation and product launches. Deploying VLC systems typically requires replacing existing light sources with new luminaires that are equipped with data communication functionality. To save the investment, it is clearly desirable to make the most of the existing illumination systems. This paper investigates the feasibility of adding data communication functionality to the existing lighting infrastructure. We do this by designing an experimental system in an indoor environment based on an off-the-shelf LED panel typically used in office environments, with the dimensions of 60 × 60 cm2. With minor modifications, the VLC function is implemented, and all of the modules of the LED panel are fully reused. A data rate of 40 Mb/s is supported at a distance of up to 2 m while using the multi-band carrierless amplitude and phase (CAP) modulation. Two main limiting factors for achieving higher data rates are observed. The first factor is the limited bandwidth of the LED string inside the panel. The second is the flicker due to the residual ripple of the bias current that is generated by the panel’s driver. Flicker is introduced by the low-cost driver, which provides bias currents that fluctuate in the low frequency range (less than several kilohertz). This significantly reduces the transmitter’s modulation depth. Concurrently, the driver can also introduce an effect that is similar to baseline wander at the receiver if the flicker is not completely filtered out. We also proposed a solution based on digital signal processing (DSP) to mitigate the flicker issue at the receiver side and its effectiveness has been confirmed.

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“…Reduced computational time can also be achieved by switching to the frequency domain by estimating the channel transfer function [19]. The accuracy of these algorithms was verified experimentally using infrared (IR) sources, e.g., in [20], [21].…”

Section: A Channel Characterization and Modeling State Of The Artmentioning

confidence: 99%

Channel Characterization and Modeling for Optical Wireless Body-Area Networks

Haddad

Khalighi

Zvánovec

et al. 2020

IEEE Open J. Commun. Soc.

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We address channel characterization and modeling for medical wireless body-area networks (WBANs) based on the optical wireless technology. We focus on the intra-WBAN communication links, i.e., between a set of medical sensors and a coordination node, placed on the patient's body. We consider a realistic mobility model, e.g., inside a hospital room, which takes into account the effect of shadowing due to body parts movements and the variations of the underlying channels. To take into account the global and local user mobility, we consider a dynamic model based on a three-dimensional animation of a walk cycle, as well as walk trajectories based on an improved random way-point mobility model. Then, Monte Carlo ray-tracing simulations are performed to obtain the channel impulse responses for different link configurations at different instants of the walk scenarios. We then derive first-and second-order statistics of the channel parameters such as the channel DC gain, delay spread, and coherence time, and furthermore, propose best fit statistical models to describe the distribution of these parameters for a general scenario.

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Experiments in Non-Line-of-Sight Li-Fi Channels

Cited by 23 publications

References 10 publications

LiFi Experiments in a Hospital

LiFi Experiments in a Hospital

A 40 Mb/s VLC System Reusing an Existing Large LED Panel in an Indoor Office Environment

Channel Characterization and Modeling for Optical Wireless Body-Area Networks

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