26,817 research outputs found
Optical Non-Orthogonal Multiple Access for Visible Light Communication
The proliferation of mobile Internet and connected devices, offering a
variety of services at different levels of performance, represents a major
challenge for the fifth generation wireless networks and beyond. This requires
a paradigm shift towards the development of key enabling techniques for the
next generation wireless networks. In this respect, visible light communication
(VLC) has recently emerged as a new communication paradigm that is capable of
providing ubiquitous connectivity by complementing radio frequency
communications. One of the main challenges of VLC systems, however, is the low
modulation bandwidth of the light-emitting-diodes, which is in the megahertz
range. This article presents a promising technology, referred to as "optical-
non-orthogonal multiple access (O-NOMA)", which is envisioned to address the
key challenges in the next generation of wireless networks. We provide a
detailed overview and analysis of the state-of-the-art integration of O-NOMA in
VLC networks. Furthermore, we provide insights on the potential opportunities
and challenges as well as some open research problems that are envisioned to
pave the way for the future design and implementation of O-NOMA in VLC systems
A Novel Approach to Fair Power Allocation for NOMA in Visible Light Communication
This paper addresses the growing demand for high-bandwidth wireless data
transmission by exploring Visible Light Communication (VLC) as an alternative
to Radio Frequency (RF) communication. In indoor scenarios, VLC systems utilize
existing lighting infrastructure for high-speed data transmission. To meet the
data rate demands of 5G and beyond, the paper proposes Non-Orthogonal Multiple
Access (NOMA) and introduces Empirical Fair Optical Power Allocation (EFOPA) to
simplify resource allocation in NOMA. EFOPA integrates NOMA with VLC, utilizing
the Artificial Bee Colony (ABC) optimization algorithm for offline resource
allocation planning. The approach then derives a simplified power allocation
equation from ABC outcomes, ensuring fair resource distribution among users.
EFOPA is compared against existing power allocation methods, demonstrating
superior fairness and reduced computational complexity. Numerical evaluations
reveal EFOPA consistently outperforms other methods across various channel
conditions, making it a robust and efficient solution for fair power allocation
in NOMA-VLC systems
Non-Orthogonal Multiple Access for Hybrid VLC-RF Networks with Imperfect Channel State Information
The present contribution proposes a general framework for the energy
efficiency analysis of a hybrid visible light communication (VLC) and Radio
Frequency (RF) wireless system, in which both VLC and RF subsystems utilize
nonorthogonal multiple access (NOMA) technology. The proposed framework is
based on realistic communication scenarios as it takes into account the
mobility of users, and assumes imperfect channel-state information (CSI). In
this context, tractable closed-form expressions are derived for the
corresponding average sum rate of NOMA-VLC and its orthogonal frequency
division multiple access (OFDMA)-VLC counterparts. It is shown extensively that
incurred CSI errors have a considerable impact on the average energy efficiency
of both NOMA-VLC and OFDMAVLC systems and hence, they should not be neglected
in practical designs and deployments. Interestingly, we further demonstrate
that the average energy efficiency of the hybrid NOMA-VLCRF system outperforms
NOMA-VLC system under imperfect CSI. Respective computer simulations
corroborate the derived analytic results and interesting theoretical and
practical insights are provided, which will be useful in the effective design
and deployment of conventional VLC and hybrid VLC-RF systems
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