315 research outputs found
Novel Modulation Techniques using Isomers as Messenger Molecules for Molecular Communication via Diffusion
In this paper, we propose novel modulation techniques using isomers as
messenger molecules for nano communication via diffusion. To evaluate
achievable rate performance, we compare the proposed techniques with
concentration-based and molecular-type-based methods. Analytical and numerical
results confirm that the proposed modulation techniques achieve higher data
transmission rate performance than conventional insulin based concepts.Comment: 5 pages, 7 figure
Recommended from our members
Theoretical insights into selective electrochemical conversion of carbon dioxide.
Electrochemical conversion of CO2 and water to valuable chemicals and fuels is one of the promising alternatives to replace fossil fuel-based processes in realizing a carbon-neutral cycle. For practical application of such technologies, suppressing hydrogen evolution reaction and facilitating the activation of stable CO2 molecules still remain major challenges. Furthermore, high production selectivity toward high-value chemicals such as ethylene, ethanol, and even n-propanol is also not easy task to achieve. To settle these challenges, deeper understanding on underlying basis of reactions such as how intermediate binding affinities can be engineered at catalyst surfaces need to be discussed. In this review, we briefly outline recent strategies to modulate the binding energies of key intermediates for CO2 reduction reactions, based on theoretical insights from density functional theory calculation studies. In addition, important design principles of catalysts and electrolytes are also provided, which would contribute to the development of highly active catalysts for CO2 electroreduction
Effect of ISI Mitigation on Modulation Techniques in Communication via Diffusion
Communication via diffusion (CvD) is an effective and energy efficient method
for transmitting information in nanonetworks. In this work, we focus on a
diffusion-based communication system where the reception process is an
absorption via receptors. Whenever a molecule hits to the receiver it is
removed from the environment. This kind of reception process is called first
passage process and it is more complicated compared to diffusion process only.
In 3-D environments, obtaining analytical solution for hitting time
distribution for realistic cases is complicated, hence we develop an end-to-end
simulator for he diffusion-based communication system that sends consecutive
symbols.
In CvD, each symbol is modulated and demodulated in a time slot called symbol
duration, however the long tail distribution of hitting time is the main
challenge that affects the symbol detection error. The molecules arriving in
the following slots become an interference source when detection takes place.
End-to-end simulator enables us to analyze the effect of inter symbol
interference (ISI) without making any assumptions on the ISI. We propose an ISI
cancellation technique that utilizes decision feedback for compensating the
effect of previously demodulated symbol. Three different modulation types are
considered with pulse, square, and cosine carrier waves. In case of constraints
on transmitter or receiver node it may not be possible to use pulse as a
carrier, and peak-to-average messenger molecule metric is defined for this
purpose. Results show that, the proposed ISI mitigation technique improves the
symbol detection performance and the amplitude-based modulations are improved
more than frequency-based modulations.Comment: 9 pages, 10 figures, 27 references, conference, two-column forma
Symbol interval optimization for molecular communication with drift
In this paper, we propose a symbol interval optimization algorithm in
molecular communication with drift. Proper symbol intervals are important in
practical communication systems since information needs to be sent as fast as
possible with low error rates. There is a trade-off, however, between symbol
intervals and inter-symbol interference (ISI) from Brownian motion. Thus, we
find proper symbol interval values considering the ISI inside two kinds of
blood vessels, and also suggest no ISI system for strong drift models. Finally,
an isomer-based molecule shift keying (IMoSK) is applied to calculate
achievable data transmission rates (achievable rates, hereafter). Normalized
achievable rates are also obtained and compared in one-symbol ISI and no ISI
systems
Multiple Access for 5G New Radio: Categorization, Evaluation, and Challenges
Next generation wireless networks require massive uplink connections as well
as high spectral efficiency. It is well known that, theoretically, it is not
possible to achieve the sum capacity of multi-user communications with
orthogonal multiple access. To meet the challenging requirements of next
generation networks, researchers have explored non-orthogonal and overloaded
transmission technologies-known as new radio multiple access (NR-MA)
schemes-for fifth generation (5G) networks. In this article, we discuss the key
features of the promising NR-MA schemes for the massive uplink connections. The
candidate schemes of NR-MA can be characterized by multiple access signatures
(MA-signatures), such as codebook, sequence, and interleaver/scrambler. At the
receiver side, advanced multi-user detection (MUD) schemes are employed to
extract each user's data from non-orthogonally superposed data according to
MA-signatures. Through link-level simulations, we compare the performances of
NR-MA candidates under the same conditions. We further evaluate the sum rate
performances of the NR-MA schemes using a 3-dimensional (3D) ray tracing tool
based system-level simulator by reflecting realistic environments. Lastly, we
discuss the tips for system operations as well as call attention to the
remaining technical challenges.Comment: 9 pages, 4 figures, 2 table
Prototyping Real-Time Full Duplex Radios
In this article, we present a real-time full duplex radio system for 5G
wireless networks. Full duplex radios are capable of opening new possibilities
in contexts of high traffic demand where there are limited radio resources. A
critical issue, however, to implementing full duplex radios, in real wireless
environments, is being able to cancel self-interference. To overcome the
self-interference challenge, we prototype our design on a software-defined
radio (SDR) platform. This design combines a dual-polarization antenna-based
analog part with a digital self-interference canceller that operates in
real-time. Prototype test results confirm that the proposed full-duplex system
achieves about 1.9 times higher throughput than a half-duplex system. This
article concludes with a discussion of implementationchallenges that remain for
researchers seeking the most viable solution for full duplex communications.Comment: To appear in IEEE Communications Magazin
Novel Modulation Techniques using Isomers as Messenger Molecules for Nano Communication Networks via Diffusion
In this paper, we propose three novel modulation techniques, i.e.,
concentration-based, molecular-type-based, and molecular-ratio-based, using
isomers as messenger molecules for nano communication networks via diffusion.
To evaluate achievable rate performance, we compare the proposed tech- niques
with conventional insulin based concepts under practical scenarios. Analytical
and numerical results confirm that the proposed modulation techniques using
isomers achieve higher data transmission rate performance (max 7.5 dB
signal-to-noise ratio gain) than the insulin based concepts. We also
investigate the tradeoff between messenger sizes and modulation orders and
provide guidelines for selecting from among several possible candidates.Comment: 10 pages and 15 figures. arXiv admin note: substantial text overlap
with arXiv:1201.091
A Universal Channel Model for Molecular Communication Systems with Metal-Oxide Detectors
In this paper, we propose an end-to-end channel model for molecular
communication systems with metal-oxide sensors. In particular, we focus on the
recently developed table top molecular communication platform. The system is
separated into two parts: the propagation and the sensor detection. There is
derived, based on this, a more realistic end-to-end channel model. However,
since some of the coefficients in the derived models are unknown, we collect a
great deal of experimental data to estimate these coefficients and evaluate how
they change with respect to the different system parameters. Finally, a noise
model is derived for the system to complete an end-to-end system model for the
tabletop platform
Channel and Noise Models for Nonlinear Molecular Communication Systems
Recently, a tabletop molecular communication platform has been developed for
transmitting short text messages across a room. The end-to-end system impulse
response for this platform does not follow previously published theoretical
works because of imperfect receiver, transmitter, and turbulent flows.
Moreover, it is observed that this platform resembles a nonlinear system, which
makes the rich body of theoretical work that has been developed by
communication engineers not applicable to this platform. In this work, we first
introduce corrections to the previous theoretical models of the end-to-end
system impulse response based on the observed data from experimentation. Using
the corrected impulse response models, we then formulate the nonlinearity of
the system as noise and show that through simplifying assumptions it can be
represented as Gaussian noise. Through formulating the system's nonlinearity as
the output a linear system corrupted by noise, the rich toolbox of mathematical
models of communication systems, most of which are based on linearity
assumption, can be applied to this platform.Comment: 10 pages, 12 figure
Network Massive MIMO for Cell-Boundary Users: From a Precoding Normalization Perspective
In this paper, we propose network massive multiple- input multiple-output
(MIMO) systems, where three radio units (RUs) connected via one digital unit
(DU) support multiple user equipments (UEs) at a cell-boundary through the same
radio resource, i.e., the same frequency/time band. For precoding designs,
zero-forcing (ZF) and matched filter (MF) with vector or matrix normalization
are considered. We also derive the formulae of the lower and upper bounds of
the achievable sum rate for each precoding. Based on our analytical results, we
observe that vector normalization is better for ZF while matrix normalization
is better for MF. Given antenna configurations, we also derive the optimal
switching point as a function of the number of active users in a network.
Numerical simulations confirm our analyticalComment: 5 pages, 5 figure
- …