Channel Modeling of Diffusive Molecular Communication with Heterogeneous Spherical Boundaries

Involving proper boundaries is an important aspect of molecular communication, especially when considering it as a potential candidate for intra-body communication. Inspired by the massive cellular environments, this paper proposes a novel approach to model the channel for a diffusive molecular communication (DMC) system in a bounded spherical environment. Specifically, this spherical boundary is made up of a reflecting and absorbing portion, whose property depends on whether it is covered by absorbing receptors (ARs). To obtain an accurate channel impulse response (CIR), we employ the homogenization technique to convert the mixed Dirichlet-Neumann boundary into a Robin boundary. Assuming these ARs with the same size and uniform distribution, we derive a valid CIR expression for the bounded DMC system with arbitrary sizes and numbers of ARs. Numerical results based on the particle-based simulation validate our analysis.