Diffusive Mobile Molecular Communications Over Time-Variant Channels

TLDR

The stochastic motion of transmitter and receiver nano‑machines causes the channel impulse response statistics to vary over time. This letter introduces a formalism for modeling time‑variant channels in diffusive molecular communication systems. The authors model a fluid environment where transmitter and receiver nano‑machines undergo Brownian motion in addition to molecular diffusion, and derive an analytical expression for the expected error probability of a simple detector. The time‑variant channel behaviour is accurately captured by adjusting the diffusion coefficient, and the derived analytical expression for error probability is validated by particle‑based simulation.

Abstract

This letter introduces a formalism for modeling time-variant channels for diffusive molecular communication systems. In particular, we consider a fluid environment where one transmitter nano-machine and one receiver nano-machine are subjected to Brownian motion in addition to the diffusive motion of the information molecules used for communication. Due to the stochastic movements of the transmitter and receiver nano-machines, the statistics of the channel impulse response change over time. We show that the time-variant behaviour of the channel can be accurately captured by appropriately modifying the diffusion coefficient of the information molecules. Furthermore, we derive an analytical expression for evaluation of the expected error probability of a simple detector for the considered system. The accuracy of the proposed analytical expression is verified via particle-based simulation of the Brownian motion.