5,355 research outputs found
Experimental Demonstration of Staggered CAP Modulation for Low Bandwidth Red-Emitting Polymer-LED based Visible Light Communications
In this paper we experimentally demonstrate, for the first time, staggered
carrier-less amplitude and phase (sCAP) modulation for visible light
communication systems based on polymer light-emitting diodes emitting at ~639
nm. The key advantage offered by sCAP in comparison to conventional multiband
CAP is its full use of the available spectrum. In this work, we compare sCAP,
which utilises four orthogonal filters to generate the signal, with a
conventional 4-band multi-CAP system and on-off keying (OOK). We transmit each
modulation format with equal energy and present a record un-coded transmission
speed of ~6 Mb/s. This represents gains of 25% and 65% over the achievable rate
using 4-CAP and OOK, respectively.Comment: 6 pages, 9 figures, IEEE ICC 2019 conferenc
Low-complexity non-coherent signal detection for nano-scale molecular communications
Nano-scale molecular communication is a viable way of exchanging information between nano-machines. In this letter, a low-complexity and non-coherent signal detection technique is proposed to mitigate the intersymbol-interference (ISI) and additive noise. In contrast to existing coherent detection methods of high complexity, the proposed non-coherent signal detector is more practical when the channel conditions are hard to acquire accurately or hidden from the receiver. The proposed scheme employs the concentration difference to detect the ISI corrupted signals and we demonstrate that it can suppress the ISI effectively. The concentration difference is a stable characteristic, irrespective of the diffusion channel conditions. In terms of complexity, by excluding matrix operations or likelihood calculations, the new detection scheme is particularly suitable for nano-scale molecular communication systems with a small energy budget or limited computation resource
Towards high-speed optical quantum memories
Quantum memories, capable of controllably storing and releasing a photon, are
a crucial component for quantum computers and quantum communications. So far,
quantum memories have operated with bandwidths that limit data rates to MHz.
Here we report the coherent storage and retrieval of sub-nanosecond low
intensity light pulses with spectral bandwidths exceeding 1 GHz in cesium
vapor. The novel memory interaction takes place via a far off-resonant
two-photon transition in which the memory bandwidth is dynamically generated by
a strong control field. This allows for an increase in data rates by a factor
of almost 1000 compared to existing quantum memories. The memory works with a
total efficiency of 15% and its coherence is demonstrated by directly
interfering the stored and retrieved pulses. Coherence times in hot atomic
vapors are on the order of microsecond - the expected storage time limit for
this memory.Comment: 13 pages, 5 figure
MOL-Eye: A New Metric for the Performance Evaluation of a Molecular Signal
Inspired by the eye diagram in classical radio frequency (RF) based
communications, the MOL-Eye diagram is proposed for the performance evaluation
of a molecular signal within the context of molecular communication. Utilizing
various features of this diagram, three new metrics for the performance
evaluation of a molecular signal, namely the maximum eye height, standard
deviation of received molecules, and counting SNR (CSNR) are introduced. The
applicability of these performance metrics in this domain is verified by
comparing the performance of binary concentration shift keying (BCSK) and BCSK
with consecutive power adjustment (BCSK-CPA) modulation techniques in a
vessel-like environment with laminar flow. The results show that, in addition
to classical performance metrics such as bit-error rate and channel capacity,
these performance metrics can also be used to show the advantage of an
efficient modulation technique over a simpler one
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