348 research outputs found
Light-Fidelity as Next Generation Network Technology: A Bibliometric Survey and Analysis
This paper delivers a systematic review and a bibliometric survey analysis of Light-Fidelity (Li-Fi) indoor implementation in Next Generation Network (NGN). The main objective of this study is to design a communication network based on NGN-Li-Fi for the indoor implementation which aims to increase user Quality of Service (QoS). The main merits and contributions of this study are the thorough and detailed analysis of the review, both in literature surveys and bibliometric analysis, as well as the discussion of the implementation model challenges of Li-Fi in both indoor and outdoor environments. The issue articulated in an indoor communication network is the possibility of intermittent connectivity due to barriers caused by line-of-sight (LOS) between the LED transmitter and receiver, handover due to channel overlap, and other network reliability issues. To realize the full potential and significant benefits of the Next Generation Network, challenges in indoor communication such as load-balancing and anticipating network congestion (traffic congestion) must be addressed. The main benefit of this study is the in-depth investigation of surveys in both selected critical literatures and bibliometric approach. This study seeks to comprehend the implications of Next Generation networks for indoor communication networks, particularly for visible light communication channels
Terminal Orientation in OFDM-based LiFi Systems
Light-fidelity (LiFi) is a wireless communication technology that employs
both infrared and visible light spectra to support multiuser access and user
mobility. Considering the small wavelength of light, the optical channel is
affected by the random orientation of a user equipment (UE). In this paper, a
random process model for changes in the UE orientation is proposed based on
data measurements. We show that the coherence time of the random orientation is
in the order of hundreds of milliseconds. Therefore, an indoor optical wireless
channel can be treated as a slowly-varying channel as its delay spread is
typically in the order of nanoseconds. A study of the orientation model on the
performance of direct-current-biased orthogonal frequency-division multiplexing
(DC-OFDM) is also presented. The performance analysis of the DC-OFDM system
incorporates the effect of diffuse link due to reflection and blockage by the
user. The results show that the diffuse link and the blockage have significant
effects, especially if the UE is located relatively far away from an access
point (AP). It is shown that the effect is notable if the horizontal distance
between the UE and the AP is greater than m in a typical
m indoor room.Comment: This work has been submitted to the IEEE for possible publication.
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Impact of Device Orientation on Error Performance of LiFi Systems
Most studies on optical wireless communications (OWCs) have neglected the
effect of random orientation in their performance analysis due to the lack of a
proper model for the random orientation. Our recent empirical-based research
illustrates that the random orientation follows a Laplace distribution for a
static user equipment (UE). In this paper, we analyze the device orientation
and assess its importance on system performance. The reliability of an OWC
channel highly depends on the availability and alignment of line-of-sight (LOS)
links. In this study, the effect of receiver orientation including both polar
and azimuth angles on the LOS channel gain are analyzed. The probability of
establishing a LOS link is investigated and the probability density function
(PDF) of signal-to-noise ratio (SNR) for a randomly-oriented device is derived.
By means of the PDF of SNR, the bit-error ratio (BER) of DC-biased optical
orthogonal frequency division multiplexing (DCO-OFDM) in additive white
Gaussian noise (AWGN) channels is evaluated. A closed-form approximation for
the BER of UE with random orientation is presented which shows a good match
with Monte-Carlo simulation results. Furthermore, the impact of the UE's random
motion on the BER performance has been assessed. Finally, the effect of random
orientation on the average signal-to-interference-plus-noise ratio (SINR) in a
multiple access points (APs) scenario is investigated.Comment: 10 pages, 11 figures, journa
Optical Wireless Communications Using Intelligent Walls
This chapter is devoted to discussing the integration of intelligent
reflecting surfaces (IRSs), or intelligent walls, in optical wireless
communication (OWC) systems. IRS technology is a revolutionary concept that
enables communication systems to harness the surrounding environment to control
the propagation of light signals. Based on this, specific key performance
indicators could be achieved by altering the electromagnetic response of the
IRSs. In the following, we discuss the background theory and applications of
IRSs and present a case study for an IRS-assisted indoor light-fidelity (LiFi)
system. We then highlight some of the challenges related to this emerging
concept and elaborate on future research directions
Introduction to indoor networking concepts and challenges in LiFi
LiFi is networked, bidirectional wireless communication with light. It is used to connect fixed and mobile devices at very high data rates by harnessing the visible light and infrared spectrum. Combined, these spectral resources are 2600 times larger than the entire radio frequency (RF) spectrum. This paper provides the motivation behind why LiFi is a very timely technology, especially for 6th generation (6G) cellular communications. It discusses and reviews essential networking technologies, such as interference mitigation and hybrid LiFi/Wi-Fi networking topologies. We also consider the seamless integration of LiFi into existing wireless networks to form heterogeneous networks across the optical and RF domains and discuss implications and solutions in terms of load balancing. Finally, we provide the results of a real-world hybrid LiFi/Wi-Fi network deployment in a software defined networking testbed. In addition, results from a LiFi deployment in a school classroom are provided, which show that Wi-Fi network performance can be improved significantly by offloading traffic to the LiFi
Optical wireless communication
Optical wireless communication has attracted significant interest recently in industry and academia. This special issue features a collection of inter-related papers with the intention to cover all necessary multidisciplinary challenges to realize optical wireless networks. We hope that this special issue will serve as a comprehensive reference and that it will be a resource which fosters many more new ideas for this rapidly emerging field
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