24,746 research outputs found
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
A Software-Defined Multi-Element VLC Architecture
In the modern era of radio frequency (RF) spectrum crunch, visible light
communication (VLC) is a recent and promising alternative technology that
operates at the visible light spectrum. Thanks to its unlicensed and large
bandwidth, VLC can deliver high throughput, better energy efficiency, and low
cost data communications. In this article, a hybrid RF/VLC architecture is
considered that can simultaneously provide light- ing and communication
coverage across a room. Considered architecture involves a novel multi-element
hemispherical bulb design, which can transmit multiple data streams over light
emitting diode (LED) modules. Simulations considering various VLC transmitter
configurations and topologies show that good link quality and high spatial
reuse can be maintained in typical indoor communication scenarios
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