16 research outputs found
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
A Vertical Channel Model of Molecular Communication based on Alcohol Molecules
The study of Molecular Communication(MC) is more and more prevalence, and
channel model of MC plays an important role in the MC System. Since different
propagation environment and modulation techniques produce different channel
model, most of the research about MC are in horizontal direction,but in nature
the communications between nano machines are in short range and some of the
information transportation are in the vertical direction, such as transpiration
of plants, biological pump in ocean, and blood transportation from heart to
brain. Therefore, this paper we propose a vertical channel model which
nano-machines communicate with each other in the vertical direction based on
pure diffusion. We first propose a vertical molecular communication model, we
mainly considered the gravity as the factor, though the channel model is also
affected by other main factors, such as the flow of the medium, the distance
between the transmitter and the receiver, the delay or sensitivity of the
transmitter and the receiver. Secondly, we set up a test-bed for this vertical
channel model, in order to verify the difference between the theory result and
the experiment data. At last, we use the data we get from the experiment and
the non-linear least squares method to get the parameters to make our channel
model more accurate.Comment: 5 pages,7 figures, Accepted for presentation at BICT 2015 Special
Track on Molecular Communication and Networking (MCN). arXiv admin note: text
overlap with arXiv:1311.6208 by other author
Local convexity inspired low-complexity non-coherent signal detector for nano-scale molecular communications
Molecular communications via diffusion (MCvD) represents a relatively new area of wireless data transfer with especially attractive characteristics for nanoscale applications. Due to the nature of diffusive propagation, one of the key challenges is to mitigate inter-symbol interference (ISI) that results from the long tail of channel response. Traditional coherent detectors rely on accurate channel estimations and incur a high computational complexity. Both of these constraints make coherent detection unrealistic for MCvD systems. In this paper, we propose a low-complexity and noncoherent signal detector, which exploits essentially the local convexity of the diffusive channel response. A threshold estimation mechanism is proposed to detect signals blindly, which can also adapt to channel variations. Compared to other noncoherent detectors, the proposed algorithm is capable of operating at high data rates and suppressing ISI from a large number of previous symbols. Numerical results demonstrate that not only is the ISI effectively suppressed, but the complexity is also reduced by only requiring summation operations. As a result, the proposed noncoherent scheme will provide the necessary potential to low-complexity molecular communications, especially for nanoscale applications with a limited computation and energy budget