Channel characterization for optical extra-WBAN links considering local and global user mobility

et al. 2021

Sensors

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In this paper, we investigate the performance of a vehicular visible light communications (VVLC) link with a non-collimated and incoherent light source (a light-emitting diode) as the transmitter (Tx), and two different optical receiver (Rx) types (a camera and photodiode (PD)) under atmospheric turbulence (AT) conditions with aperture averaging (AA). First, we present simulation results indicating performance improvements in the signal-to-noise ratio (SNR) under AT with AA with increasing size of the optical concentrator. Experimental investigations demonstrate the potency of AA in mitigating the induced signal fading due to the weak to moderate AT regimes in a VVLC system. The experimental results obtained with AA show that the link’s performance was stable in terms of the average SNR and the peak SNR for the PD and camera-based Rx links, respectively with <1 dB SNR penalty for both Rxs, as the strength of AT increases compared with the link with no AT.

“…Note that the daytime ambient sunlight-induced shot noise is the dominant noise source in VVLC, which is expressed as [ 34 , 35 ]:

where

is the electron charge, and

is the system’s bandwidth. Note that for the on–off keying (OOK) data format,

[ 36 ].

is the ambient noise current, and during the daytime

, which can be expressed as [ 37 ]:

where

is the active area the PD;

is the incidence angle;

is the solar irradiance;

and

are the integration limits, i.e., the wavelength band, which are 405–690 nm for the visible range;

and

represent the gain of the optical concentrator (OC) and the transmittance of the optical filter, respectively.…”

Section: System Descriptionmentioning

confidence: 99%

“…

is the ambient noise current, and during the daytime

, which can be expressed as [ 37 ]:

where

is the active area the PD;

is the incidence angle;

is the solar irradiance;

and

are the integration limits, i.e., the wavelength band, which are 405–690 nm for the visible range;

and

where

is Boltzmann’s constant,

is the absolute temperature in Kelvin,

is the load resistance, and

is the dark current.

denotes the average optical transmit power, and H for the LOS VVLC link with a symmetrical Tx light radiation pattern can be expressed as [ 33 ]:

where

denotes the irradiance angle,

is the angular field of view (AFOV) semi-angle of the Rx, and

is the distance between the Tx and Rx.…”

Section: System Descriptionmentioning

confidence: 99%

Performance of Vehicular Visible Light Communications under the Effects of Atmospheric Turbulence with Aperture Averaging

Eso

Ghassemlooy

et al. 2021

Sensors

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“…Thermal noise is generated due to the random motion of charge carriers [9] and its variance is given as [23,24]:…”

Section: B Thermal and Shot Noise Sourcesmentioning

confidence: 99%

Fundamental Analysis of Vehicular Light Communications and the Mitigation of Sunlight Noise

Eso

Ghassemlooy

IEEE Trans. Veh. Technol.

et al. 2021

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Intelligent transport systems (ITS) rely upon the connectivity, cooperation and automation of vehicles aimed at the improvement of safety and efficiency of the transport system. Connectivity, which is a key component for the practical implementation of vehicular light communications (VeLC) systems in ITS, must be carefully studied prior to design and implementation. In this paper, we carry out a performance evaluation study on the use of different vehicle taillights (TLs) as the transmitters in a VeLC system. We show that, the transmission coverage field of view and the link span depend on TLs illumination patterns and the transmit power levels, respectively, which fail to meet the typical communication distances in vehicular environments. This paper proposes an infrared-based VeLC system to meet the transmission range in daytimes under Sunlight noise. We show that, at the forward error correction bit error rate limit of 3.8 ×10 -3 , the communication distances of the proposed link are 63, 72, and > 89 m compared with 4.5, 5.4 and 6.3 m for BMW's vehicle TL at data rates of 10, 6, and 2 Mbps, respectively. Index Terms-vehicular visible light communications, fundamental analysis, intelligent transport systems, infrared, sunlight noise I. INTRODUCTIONThe wireless exchange of traffic information between the vehicles and roadside infrastructure, which is part of the emerging intelligent transport systems (ITS), can significantly enhance the road safety and the efficiency of transportation networks [1]. ITS involves the provision of safe driving information, which include warning messages on the road terrains, pedestrian crossing the road, driving speed limits, etc. Presently, the radio frequency (RF) wireless communications technology is the established option in ITS, which is best known as the dedicated short-range communications (DSRC). DSRC

“…The patient's body was modeled by a simple rectangular surface in [31], [33], and by a combination of three rectangular volumes in [34], whereas a static three-dimensional (3D) model was used in [32]. Recently, in [35], we considered extra-WBAN channel characterization and modeling using a similar MCRT approach as in the present work.…”

Section: A Channel Characterization and Modeling State Of The Artmentioning

confidence: 99%

Channel Characterization and Modeling for Optical Wireless Body-Area Networks

Haddad

Khalighi

IEEE Open J. Commun. Soc.

et al. 2020

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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.