22 research outputs found
Channel impulse response-based source localization in a diffusion-based molecular communication system
Molecular source localization finds its applications in future healthcare systems, including proactive diagnostics. This work localizes a molecular source in a diffusion based molecular communication (DbMC) system via a minimal set of passive anchor nodes and a fusion center. Two methods are presented which both utilize (the peak of) the channel impulse response measurements to uniquely localize the source, under the assumption that the molecular source of interest lies within the open convex鈥恏ull of the sensor/anchor nodes. The first method is a one鈥恠hot, triangulation鈥恇ased approach which estimates the unknown location of the molecular source using least鈥恠quares method. The second method is an iterative approach, which utilizes the gradient鈥恉escent control law to minimize a non鈥恈onvex cost function. The corresponding Cramer鈥怰ao bound (CRB) is also derived. Simulation results reveal that: i) the gradient鈥恉escent method outperforms the triangulation method (in terms of mean squared error performance) for a wide range of values of signal鈥恡o鈥恘oise ratio; ii) the gradient鈥恉escent method converges to the true source location uniformly (in less than hundred iterations)
Insights from the Design Space Exploration of Flow-Guided Nanoscale Localization
Nanodevices with Terahertz (THz)-based wireless communication capabilities
are providing a primer for flow-guided localization within the human
bloodstreams. Such localization is allowing for assigning the locations of
sensed events with the events themselves, providing benefits in precision
medicine along the lines of early and precise diagnostics, and reduced costs
and invasiveness. Flow-guided localization is still in a rudimentary phase,
with only a handful of works targeting the problem. Nonetheless, the
performance assessments of the proposed solutions are already carried out in a
non-standardized way, usually along a single performance metric, and ignoring
various aspects that are relevant at such a scale (e.g., nanodevices' limited
energy) and for such a challenging environment (e.g., extreme attenuation of
in-body THz propagation). As such, these assessments feature low levels of
realism and cannot be compared in an objective way. Toward addressing this
issue, we account for the environmental and scale-related peculiarities of the
scenario and assess the performance of two state-of-the-art flow-guided
localization approaches along a set of heterogeneous performance metrics such
as the accuracy and reliability of localization.Comment: 6 pages, 4 figures, 2 table
Diffusive MIMO Molecular Communications: Channel Estimation, Equalization and Detection
In diffusion-based communication, as for molecular systems, the achievable
data rate is low due to the stochastic nature of diffusion which exhibits a
severe inter-symbol-interference (ISI). Multiple-Input Multiple-Output (MIMO)
multiplexing improves the data rate at the expense of an inter-link
interference (ILI). This paper investigates training-based channel estimation
schemes for diffusive MIMO (D-MIMO) systems and corresponding equalization
methods. Maximum likelihood and least-squares estimators of mean channel are
derived, and the training sequence is designed to minimize the mean square
error (MSE). Numerical validations in terms of MSE are compared with Cramer-Rao
bound derived herein. Equalization is based on decision feedback equalizer
(DFE) structure as this is effective in mitigating diffusive ISI/ILI.
Zero-forcing, minimum MSE and least-squares criteria have been paired to DFE,
and their performances are evaluated in terms of bit error probability. Since
D-MIMO systems are severely affected by the ILI because of short transmitters
inter-distance, D-MIMO time interleaving is exploited as countermeasure to
mitigate the ILI with remarkable performance improvements. The feasibility of a
block-type communication including training and data equalization is explored
for D-MIMO, and system-level performances are numerically derived.Comment: Accepted paper at IEEE transaction on Communicatio
Abnormality Detection inside Blood Vessels with Mobile Nanomachines
Motivated by the numerous healthcare applications of molecular communication
within Internet of Bio-Nano Things (IoBNT), this work addresses the problem of
abnormality detection in a blood vessel using multiple biological embedded
computing devices called cooperative biological nanomachines (CNs), and a
common receiver called the fusion center (FC). Due to blood flow inside a
vessel, each CN and the FC are assumed to be mobile. In this work, each of the
CNs perform abnormality detection with certain probabilities of detection and
false alarm by counting the number of molecules received from a source, e.g.,
infected tissue. These CNs subsequently report their local decisions to a FC
over a diffusion-advection blood flow channel using different types of
molecules in the presence of inter-symbol interference, multi-source
interference, and counting errors. Due to limited computational capability at
the FC, OR and AND logic based fusion rules are employed to make the final
decision after obtaining each local decision based on the optimal likelihood
ratio test. For the aforementioned system, probabilities of detection and false
alarm at the FC are derived for OR and AND fusion rules. Finally, simulation
results are presented to validate the derived analytical results, which provide
important insights.Comment: Submitted to IEEE Transactions on Molecular, Biological, and
Multi-Scale Communications Letters for possible publicatio
Adaptive detection and ISI mitigation for mobile molecular communication
Current studies on modulation and detection schemes in molecular communication mainly focus on the scenarios with static transmitters and receivers. However, mobile molecular communication is needed in many envisioned applications, such as target tracking and drug delivery. Until now, investigations about mobile molecular communication have been limited. In this paper, a static transmitter and a mobile bacterium-based receiver performing random walk are considered. In this mobile scenario, the channel impulse response changes due to the dynamic change of the distance between the transmitter and the receiver. Detection schemes based on fixed distance fail in signal detection in such a scenario. Furthermore, the intersymbol interference (ISI) effect becomes more complex due to the dynamic character of the signal which makes the estimation and mitigation of the ISI even more difficult. In this paper, an adaptive ISI mitigation method and two adaptive detection schemes are proposed for this mobile scenario. In the proposed scheme, adaptive ISI mitigation, estimation of dynamic distance and the corresponding impulse response reconstruction are performed in each symbol interval. Based on the dynamic channel impulse response in each interval, two adaptive detection schemes, concentration-based adaptive threshold detection (CATD) and peak-time-based adaptive detection (PAD), are proposed for signal detection. Simulations demonstrate that, the ISI effect is significantly reduced and the adaptive detection schemes are reliable and robust for mobile molecular communication
Biologically inspired bio-cyber interface architecture and model for internet of Bio-NanoThings applications
With the advent of nanotechnology, concepts related
to the Internet of Things, such as the Internet of NanoThings
and Internet of Bio-NanoThings (IoBNT) have also emerged
in the classical literature. The main concern of this paper is
the IoBNT, which projects the prospective application domain
where the activities of very tiny, biocompatible, and non-intrusive
devices operating in an in-body nanonetwork can be monitored
and controlled through the Internet. In this paper, we present
an illustrative scenario and system model of an IoBNT for
application in an advanced healthcare delivery system. To address
one of the major challenges of the IoBNT, we present an
exemplary architecture and model of a bio-cyber interface
for connecting the conventional electromagnetic-based Internet
to the biochemical signaling-based bionanonetwork. The biocyber
interface is designed and modeled by employing biological
concepts, such as the responsiveness of certain biomolecules to
thermal and light stimuli, and the bioluminescence phenomenon
of some biochemical reactions. The analysis in this paper focuses
on the system that comprises the bio-cyber interface and the
information propagation network of the blood vessel that leads to
the in-body nanonetwork location. The effects of the system and
design parameters associated with the IoBNT models presented
are numerically evaluated.The Sentech Chair in Broadband Wireless Multimedia Communications at the University of Pretoria and the Department of Trade and Industry THRIP Program.http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=26hb2016Electrical, Electronic and Computer Engineerin