1089-7798 (c) 2018 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/LCOMM.2018.2875445, IEEE Communications Letters IEEE COMMUNICATIONS LETTERS 1 Experimental Results on the Open-Air Transmission of Macro-Molecular Communication using Membrane Inlet Mass Spectrometry Daniel Tunc ¸ McGuiness, Stamatios Giannoukos, Alan Marshall, Senior Member, IEEE and Stephen Taylor Abstract—Molecular communication (MC) is a method where the transmission of information involves the use of molecules rather than electromagnetic (EM) waves. In this paper an open-air transmission MC experiment is conducted to study signal behavior and the noise. A mass spectrometer is used as the detector and an in-house-built odor generator is used as transmitter. It is shown that the signal amplitude loss of the signal can be modelled by using advection-diffusion with decay equation. In addition, the noise of the system has shown to have similar characteristics to that of additive white Gaussian noise (AWGN). Index Terms—Molecular Communication; Mass Spectrometry; Open-air Transmission I. I NTRODUCTION T RANSMISSION of information using chemicals, Molec- ular Communication (MC), has been utilized by nature for many years [1]. However, as this communication can involve both very small scales (intercellular, DNA etc.) and large scales (bees, eels [2]), MC can be classified based on the transmission distance: micro- and macro-scale. The first study of MC was done in the micro-scale, which can be defined as a system within the transmission range of nm - μm [3]. The antennae size poses a significant problem when shrinking an EM-based system to the micro-scale [4], and because of this, MC has been shown to be a good alternative for micro-scales. There have been numerous studies in micro- scale, such as transmission using diffusion [5], modulation [6] and channel capacity [7]. Using MC at the macro-scale (cm - m) [8] is a relatively new field of study compared to micro-scale. There have been a few practical [9]–[13] and theoretical [14] studies, which has shown the possibility macro-scale molecular communi- cations. There are areas in which the use of macro-scale communications can be a better choice compare to EM. In [15] it was shown that signal attenuation per unit length in a copper pipe for MC was less than EM. There are several applications of macro-scale communications, such as infrastructure monitoring [16], a tool for studying biological communications [2] and odor transmission using digital media [17]. The research was funded from the Engineering and Physical Sciences Re- search Council (EPSRC) under the grant agreement: EP/M029425/1 ’Creating a Stink - Investigating Olfactory Transport Streams’. The authors are with the Department of Electrical Engineering & Electron- ics, University of Liverpool, L69 3GJ, UK (emails: danielmc@liverpool.ac.uk, stamgian@liverpool.ac.uk, alanm@liverpool.ac.uk, S.Taylor@liv.ac.uk) Corresponding author: Daniel Tunc ¸ McGuiness As mentioned, macro-scale MC is a new field with relatively few experimental studies done [10]–[13]. Some of the impor- tant aspects of communication systems; noise analysis, signal energy and signal amplitude analysis of open environment transmission have yet to be studied. In this study the open-air transmission and the noise analysis of MC is investigated at the macro-scale. In the experiment, an in-house-built gas generator and a quadrupole mass analyzer were used. Noise analysis were undertaken and it is shown that the loss in signal amplitude and signal energy over distance can be modelled using advection-diffusion equation (ADE) with decay. The results show that the amplitude of the transmitted signal experiences a non-linear attenuation that differs significantly from EM-wave propagation channels. II. EXPERIMENTAL SETUP In order to test the open-air transmission of MC, two devices were employed. The generation and transmission of chemicals based on a message was made using an in-house-built odor generator [18], [19], and the detection of the chemical was made with a membrane inlet mass spectrometer (MIMS) having a quadrupole mass analyzer (QMA) [12], [18]. A QMA is an instrument capable of analyzing and distinguishing charged ions or sample molecules by their motion in an applied electric field. The analyzer of the MS allows the detection of ions with a particular mass-to-charge (m/z) ratio [12], [18], making it a useful tool for use in MC. The details of the experiment can be seen in [12], [18] with the major difference is the difference of the medium whereby the transmission environment is open space instead of a cylindrical pipe. The diagram for the experimental setup can be seen in Figure 1. In this study, the open-air transmission of macro-MC is con- ducted. Here, open-air transmission, is defined as a boundary- less area where the space between the transmitter and the receiver is open to outside interference and not protected by a medium. This makes it challenging for the system as small disturbances from the ambient environment, in addition to the unwanted diffusion of the transmitted signal flow, can cause problems in retrieving the signal and the unguided medium can see a sudden shift in the concentration, producing lower signal amplitude and energy values with increasing distance. The parameters of the experiment are given in Table I. III. MOLECULAR TRANSMISSION Molecular propagation in a medium can be explained using the general convection-diffusion equation is shown below [20]; brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by University of Liverpool Repository