Modulation Analysis in Macro-Molecular Communications

Molecular communication (MC) involves the transmission of information using particles (i.e., molecules). Research into the field has been dominated by micro-scale, and most of the effects of macro-scale communication have yet to be studied. In this paper, the modulation and transmission of MC at macro-scale are investigated. For the transmitter, an in-house-built odor generator was used, and as the detector, a mass spectrometer with a quadrupole mass analyzer was employed. Various 2-level, 4-level, and 8-level modulation schemes were tested experimentally. A simulation framework, developed for the first time, was used for comparison with the experimental results. It was shown that communication can be modeled using a variant of the advection-diffusion equation and that it gives good agreement with the experimental results. A symbol-error-rate (SER) analysis of both the experimental and simulation results was analyzed. It was found that increasing the distance has a detrimental effect on both the channel capacity and the SER, whereas velocity and diffusivity have a decreasing effect on the SER and an increasing effect on the channel capacity. A channel model was developed based on the asymmetric behavior of the communications, and the optimal sampling period was developed that subsequently permitted analysis of the ISI of the communications scheme.