Chemical Propagation Pattern for Molecular Communications

In a diffusion-based molecular communication system, molecules are employed to convey information. When we focus on absorbing receivers, we need to consider propagation and reception processes in a framework of first passage processes. For this kind of molecular communication system, the characteristics of the channel is also affected by the shape of the transmitter. In the literature, most studies focus on systems with a point transmitter due to circular symmetry. In this letter, we address the propagation and reception patterns of chemical signals emitted from a spherical transmitter. We also investigate the directivity gain achieved by the reflecting spherical transmitter. We quantify the power gain by measuring the received power at different angles on a circular region.