4 research outputs found
Hardware Implementation of A Non-RLL Soft-decoding Beacon-based Visible Light Communication Receiver
Visible light communication (VLC)-based beacon systems, which usually
transmit identification (ID) information in small-size data frames are applied
widely in indoor localization applications. There is one fact that flicker of
LED light should be avoid in any VLC systems. Current flicker mitigation
solutions based on run-length limited (RLL) codes suffer from reduced code
rates, or are limited to hard-decoding forward error correction (FEC) decoders.
Recently, soft-decoding techniques of RLL-codes are proposed to support
soft-decoding FEC algorithms, but they contain potentials of high-complexity
and time-consuming computations. Fortunately, non-RLL direct current
(DC)-balance solutions can overcome the drawbacks of RLL-based algorithms,
however, they meet some difficulties in system latency or inferior
error-correction performances. Recently, non-RLL flicker mitigation solution
based on Polar code has proved to be an optimal approach due to its natural
equal probabilities of short runs of 1's and 0's with high error-correction
performance. However, we found that this solution can only maintain the DC
balance only when the data frame length is sufficiently long. Accordingly,
short beacon-based data frames might still be a big challenge for flicker
mitigation in such non-RLL cases. In this paper, we introduce a flicker
mitigation solution designed for VLC-based beacon systems that combines a
simple pre-scrambler with a Polar encoder which has a codeword smaller than the
previous work 8 times. We also propose a hardware architecture for the proposed
compact non-RLL VLC receiver for the first time. Also, a 3-bit soft-decision
filter is introduce to enable soft-decoding of Polar decoder to improve the
performance of the receiver.Comment: In review process of ATC'18, HCMC, Vietna
Integrated RF/Optical Wireless Networks for Improving QoS in Indoor and Transportation Applications
Communications based solely on radio frequency (RF) networks cannot provide
adequate quality of service for the rapidly growing demands of wireless
connectivity. Since devices operating in the optical spectrum do not interfere
with those using the RF spectrum, wireless networks based on the optical
spectrum can be added to existing RF networks to fulfill this demand. Hence,
optical wireless communication (OWC) technology can be an excellent complement
to RF-based technology to provide improved service. Promising OWC systems
include light fidelity (LiFi), visible light communication, optical camera
communication (OCC), and free-space optical communication (FSOC). OWC and RF
systems have differing limitations, and the integration of RF and optical
wireless networks can overcome the limitations of both systems. This paper
describes an LiFi/femtocell hybrid network system for indoor environments. Low
signal-to-interference-plus-noise ratios and the shortage bandwidth problems of
existing RF femtocell networks can be overcome with the proposed hybrid model.
Moreover, we describe an integrated RF/optical wireless system that can be
employed for users inside a vehicle, remote monitoring of ambulance patients,
vehicle tracking, and vehicle-to-vehicle communications. We consider LiFi, OCC,
and FSOC as the optical wireless technologies to be used for communication
support in transportation, and assume macrocells, femtocells, and wireless
fidelity to be the corresponding RF technologies. We describe handover
management-including detailed call flow, interference management, link
reliability improvement, and group handover provisioning-for integrated
networks. Performance analyses demonstrate the significance of the proposed
integrated RF/optical wireless systems
A Comparative Survey of Optical Wireless Technologies: Architectures and Applications
New high-data-rate multimedia services and applications are evolving
continuously and exponentially increasing the demand for wireless capacity of
fifth-generation (5G) and beyond. The existing radio frequency (RF)
communication spectrum is insufficient to meet the demands of future
high-datarate 5G services. Optical wireless communication (OWC), which uses an
ultra-wide range of unregulated spectrum, has emerged as a promising solution
to overcome the RF spectrum crisis. It has attracted growing research interest
worldwide in the last decade for indoor and outdoor applications. OWC offloads
huge data traffic applications from RF networks. A 100 Gb/s data rate has
already been demonstrated through OWC. It offers services indoors as well as
outdoors, and communication distances range from several nm to more than 10000
km. This paper provides a technology overview and a review on optical wireless
technologies, such as visible light communication, light fidelity, optical
camera communication, free space optical communication, and light detection and
ranging. We survey the key technologies for understanding OWC and present
state-of-the-art criteria in aspects, such as classification, spectrum use,
architecture, and applications. The key contribution of this paper is to
clarify the differences among different promising optical wireless technologies
and between these technologies and their corresponding similar existing RF
technologie
A Contemporary Survey on Free Space Optical Communication: Potential, Technical Challenges, Recent Advances and Research Direction
Optical wireless communication (OWC) covering an ultra-wide range of
unlicensed spectrum has emerged as an extent efficient solution to mitigate
conventional RF spectrum scarcity ranging from communication distances from nm
to several kilometers. Free space optical (FSO) systems operating near IR (NIR)
band in OWC links has received substantial attention for enormous data
transmission between fixed transceivers covering few kilometers path distance
due to high optical bandwidth and higher bit rate as well. Despite the
potential benefits of FSO technology, its widespread link reliability suffers
especially in the long-range deployment due to atmospheric turbulence, cloud
induced fading, some other environmental factors such as fog, aerosol,
temperature variations, storms, heavy rain, cloud, pointing error, and
scintillation. FSO has the potential to offloading massive traffic demands from
RF networks, consequently the combined application of FSO/RF and radio over FSO
(RoFSO) systems is regarded as an excellent solution to support 5G and beyond
for improving the limitations of an individual system. This survey presents the
overview of several key technologies and implications of state-of-the-art
criteria in terms of spectrum reuse, classification, architecture and
applications are described for understanding FSO. This paper provides
principle, significance, demonstration, and recent technological development of
FSO technology among different appealing optical wireless technologies. The
opportunities in the near future, the potential challenges that need to be
addressed to realize the successful deployment of FSO schemes are outlined.Comment: 59 pages, 14 figure