5,538 research outputs found
Amplify-and-Forward Relaying in Two-Hop Diffusion-Based Molecular Communication Networks
This paper studies a three-node network in which an intermediate
nano-transceiver, acting as a relay, is placed between a nano-transmitter and a
nano-receiver to improve the range of diffusion-based molecular communication.
Motivated by the relaying protocols used in traditional wireless communication
systems, we study amplify-and-forward (AF) relaying with fixed and variable
amplification factor for use in molecular communication systems. To this end,
we derive a closed-form expression for the expected end-to-end error
probability. Furthermore, we derive a closed-form expression for the optimal
amplification factor at the relay node for minimization of an approximation of
the expected error probability of the network. Our analytical and simulation
results show the potential of AF relaying to improve the overall performance of
nano-networks.Comment: 7 pages, 6 figures, 1 table. Submitted to the 2015 IEEE Global
Communications Conference (GLOBECOM) on April 15, 201
Molecular Signal Modeling of a Partially Counting Absorbing Spherical Receiver
To communicate at the nanoscale, researchers have proposed molecular
communication as an energy-efficient solution. The drawback to this solution is
that the histogram of the molecules' hitting times, which constitute the
molecular signal at the receiver, has a heavy tail. Reducing the effects of
this heavy tail, inter-symbol interference (ISI), has been the focus of most
prior research. In this paper, a novel way of decreasing the ISI by defining a
counting region on the spherical receiver's surface facing towards the
transmitter node is proposed. The beneficial effect comes from the fact that
the molecules received from the back lobe of the receiver are more likely to be
coming through longer paths that contribute to ISI. In order to justify this
idea, the joint distribution of the arrival molecules with respect to angle and
time is derived. Using this distribution, the channel model function is
approximated for the proposed system, i.e., the partially counting absorbing
spherical receiver. After validating the channel model function, the
characteristics of the molecular signal are investigated and improved
performance is presented. Moreover, the optimal counting region in terms of bit
error rate is found analytically.Comment: submitted to Transactions on Communication
Receivers for Diffusion-Based Molecular Communication: Exploiting Memory and Sampling Rate
In this paper, a diffusion-based molecular communication channel between two
nano-machines is considered. The effect of the amount of memory on performance
is characterized, and a simple memory-limited decoder is proposed and its
performance is shown to be close to that of the best possible imaginable
decoder (without any restriction on the computational complexity or its
functional form), using Genie-aided upper bounds. This effect is specialized
for the case of Molecular Concentration Shift Keying; it is shown that a
four-bits memory achieved nearly the same performance as infinite memory. Then
a general class of threshold decoders is considered and shown not to be optimal
for Poisson channel with memory, unless SNR is higher than a value specified in
the paper. Another contribution is to show that receiver sampling at a rate
higher than the transmission rate, i.e., a multi-read system, can significantly
improve the performance. The associated decision rule for this system is shown
to be a weighted sum of the samples during each symbol interval. The
performance of the system is analyzed using the saddle point approximation. The
best performance gains are achieved for an oversampling factor of three.Comment: Submitted to JSA
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