54,658 research outputs found
On the Performance of Single- and Multi-carrier Modulation Schemes for Indoor Visible Light Communication Systems
In this paper, we investigate and compare the performance of single- and
multi-carrier modulation schemes for indoor visible light communication (VLC).
Particularly, the performances of single carrier frequency domain equalization
(SCFDE), orthogonal frequency division multiplexing (OFDM) and on-off keying
(OOK) with minimum mean square error equalization (MMSE) are analyzed in order
to mitigate the effect of multipath distortion of the indoor optical channel
where nonlinearity distortion of light emitting diode (LED) transfer function
is taken into account. Our results indicate that SCFDE system, in contrast to
OFDM system, does not suffer from high peak to average power ratio (PAPR) and
can outperform OFDM and OOK systems. We further investigate the impact of LED
bias point on the performance of OFDM systems and show that biasing LED with
the optimum value can significantly enhance the performance of the system.
Bit-interleaved coded modulation (BICM) is also considered for OFDM and SCFDE
systems to further compensate signal degradation due to inter-symbol
interference (ISI) and LED nonlinearity.Comment: 6 Pages, IEEE Globecom conference 201
Feasibility of an Electro-Optic Link for Bondpad-less CMOS Lab-on-Chips
This paper explores the feasibility of developing CMOS-based lab-on-chips to analyse the properties of a fluid, without the need for bond wires. Both inductive and electro-optical schemes are suggested as possible solutions. Specifically, this paper details a novel approach in achieving electro-optical modulation in unmodified, commercially-available CMOS technology. By exploiting the plasma dispersion effect, it is shown how mid-infrared light can be modulated using parasitic structures designed in a CMOS integrated circuit. Both the fundamental theory and practical realisation are supported with measured data from an experimental setup.Accepted versio
Cellular Underwater Wireless Optical CDMA Network: Potentials and Challenges
Underwater wireless optical communications is an emerging solution to the
expanding demand for broadband links in oceans and seas. In this paper, a
cellular underwater wireless optical code division multiple-access (UW-OCDMA)
network is proposed to provide broadband links for commercial and military
applications. The optical orthogonal codes (OOC) are employed as signature
codes of underwater mobile users. Fundamental key aspects of the network such
as its backhaul architecture, its potential applications and its design
challenges are presented. In particular, the proposed network is used as
infrastructure of centralized, decentralized and relay-assisted underwater
sensor networks for high-speed real-time monitoring. Furthermore, a promising
underwater localization and positioning scheme based on this cellular network
is presented. Finally, probable design challenges such as cell edge coverage,
blockage avoidance, power control and increasing the network capacity are
addressed.Comment: 11 pages, 10 figure
Connecting the World of Embedded Mobiles: The RIOT Approach to Ubiquitous Networking for the Internet of Things
The Internet of Things (IoT) is rapidly evolving based on low-power compliant
protocol standards that extend the Internet into the embedded world. Pioneering
implementations have proven it is feasible to inter-network very constrained
devices, but had to rely on peculiar cross-layered designs and offer a
minimalistic set of features. In the long run, however, professional use and
massive deployment of IoT devices require full-featured, cleanly composed, and
flexible network stacks.
This paper introduces the networking architecture that turns RIOT into a
powerful IoT system, to enable low-power wireless scenarios. RIOT networking
offers (i) a modular architecture with generic interfaces for plugging in
drivers, protocols, or entire stacks, (ii) support for multiple heterogeneous
interfaces and stacks that can concurrently operate, and (iii) GNRC, its
cleanly layered, recursively composed default network stack. We contribute an
in-depth analysis of the communication performance and resource efficiency of
RIOT, both on a micro-benchmarking level as well as by comparing IoT
communication across different platforms. Our findings show that, though it is
based on significantly different design trade-offs, the networking subsystem of
RIOT achieves a performance equivalent to that of Contiki and TinyOS, the two
operating systems which pioneered IoT software platforms
Wireless sensors and IoT platform for intelligent HVAC control
Energy consumption of buildings (residential and non-residential) represents approximately 40% of total world electricity consumption, with half of this energy consumed by HVAC systems. Model-Based Predictive Control (MBPC) is perhaps the technique most often proposed for HVAC control, since it offers an enormous potential for energy savings. Despite the large number of papers on this topic during the last few years, there are only a few reported applications of the use of MBPC for existing buildings, under normal occupancy conditions and, to the best of our knowledge, no commercial solution yet. A marketable solution has been recently presented by the authors, coined the IMBPC HVAC system. This paper describes the design, prototyping and validation of two components of this integrated system, the Self-Powered Wireless Sensors and the IOT platform developed. Results for the use of IMBPC in a real building under normal occupation demonstrate savings in the electricity bill while maintaining thermal comfort during the whole occupation schedule.QREN SIDT [38798]; Portuguese Foundation for Science & Technology, through IDMEC, under LAETA [ID/EMS/50022/2013
Wireless communication, identification and sensing technologies enabling integrated logistics: a study in the harbor environment
In the last decade, integrated logistics has become an important challenge in
the development of wireless communication, identification and sensing
technology, due to the growing complexity of logistics processes and the
increasing demand for adapting systems to new requirements. The advancement of
wireless technology provides a wide range of options for the maritime container
terminals. Electronic devices employed in container terminals reduce the manual
effort, facilitating timely information flow and enhancing control and quality
of service and decision made. In this paper, we examine the technology that can
be used to support integration in harbor's logistics. In the literature, most
systems have been developed to address specific needs of particular harbors,
but a systematic study is missing. The purpose is to provide an overview to the
reader about which technology of integrated logistics can be implemented and
what remains to be addressed in the future
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