Smart antennas for diffusion-based molecular communications

Diffusion-based molecular communications are characterized by the Brownian motion of the signal molecules in their path from the transmitting nanomachine to the receiving one, which prevents directionality in the transmitted signal. In order to make diffusion-based molecular communications more reliable, we worked on the receiver side to improve the capability of receiving biological signals. Inspired by smart antennas in conventional wireless communications, we designed a directional receiver nanomachine, with the aim of increasing the average concentration of signal molecules close to its surface so as to improve the received signal strength. In more detail, we considered a spherical receiver covered by a finite number of receptors, and provided with a purely reflecting shell at a configurable distance from the receiver surface, whose shape is a spherical cap or a cylinder. The presence of the shell allows a number of signal molecules to remain trapped close to the receiver surface for a while. This phenomenon increases the probability of assimilating a signal molecule by one of the receptors deployed on the receiver surface. Through an extensive simulation campaign, we compared the received signal intensity obtained with the smart antennas with the that obtainable in standard settings. From the analysis of results, we identified the most suitable settings in terms of aperture of the shell and distance of the shell from the receiver.