6 research outputs found
Symbol Synchronization for Diffusive Molecular Communication Systems
Symbol synchronization refers to the estimation of the start of a symbol
interval and is needed for reliable detection. In this paper, we develop a
symbol synchronization framework for molecular communication (MC) systems where
we consider some practical challenges which have not been addressed in the
literature yet. In particular, we take into account that in MC systems, the
transmitter may not be equipped with an internal clock and may not be able to
emit molecules with a fixed release frequency. Such restrictions hold for
practical nanotransmitters, e.g. modified cells, where the lengths of the
symbol intervals may vary due to the inherent randomness in the availability of
food and energy for molecule generation, the process for molecule production,
and the release process. To address this issue, we propose to employ two types
of molecules, one for synchronization and one for data transmission. We derive
the optimal maximum likelihood (ML) symbol synchronization scheme as a
performance upper bound. Since ML synchronization entails high complexity, we
also propose two low-complexity synchronization schemes, namely a peak
observation-based scheme and a threshold-trigger scheme, which are suitable for
MC systems with limited computational capabilities. Our simulation results
reveal the effectiveness of the proposed synchronization~schemes and suggest
that the end-to-end performance of MC systems significantly depends on the
accuracy of symbol synchronization.Comment: This paper has been accepted for presentation at IEEE International
Conference on Communications (ICC) 201
A Survey on Modulation Techniques in Molecular Communication via Diffusion
This survey paper focuses on modulation aspects of molecular communication,
an emerging field focused on building biologically-inspired systems that embed
data within chemical signals. The primary challenges in designing these systems
are how to encode and modulate information onto chemical signals, and how to
design a receiver that can detect and decode the information from the corrupted
chemical signal observed at the destination. In this paper, we focus on
modulation design for molecular communication via diffusion systems. In these
systems, chemical signals are transported using diffusion, possibly assisted by
flow, from the transmitter to the receiver. This tutorial presents recent
advancements in modulation and demodulation schemes for molecular communication
via diffusion. We compare five different modulation types: concentration-based,
type-based, timing-based, spatial, and higher-order modulation techniques. The
end-to-end system designs for each modulation scheme are presented. In
addition, the key metrics used in the literature to evaluate the performance of
these techniques are also presented. Finally, we provide a numerical bit error
rate comparison of prominent modulation techniques using analytical models. We
close the tutorial with a discussion of key open issues and future research
directions for design of molecular communication via diffusion systems.Comment: Preprint of the accepted manuscript for publication in IEEE Surveys
and Tutorial