Channel Impulse Responses in Diffusive Molecular Communication with Spherical Transmitters

TL;DR

This paper derives and verifies closed-form channel impulse responses for spherical molecular transmitters in diffusive communication, improving accuracy over point source assumptions especially at short distances.

Contribution

It introduces a spherical transmitter model for molecular communication, providing closed-form responses in 1D and numerical solutions in 3D, enhancing modeling accuracy.

Findings

Spherical transmitter model is more accurate than point source assumption at short distances.

Derived closed-form responses are validated with particle-based simulations.

Surface molecule release from spherical transmitters is also analyzed via simulation.

Abstract

Molecular communication is an emerging paradigm for systems that rely on the release of molecules as information carriers. Communication via molecular diffusion is a popular strategy that is ubiquitous in nature and very fast over distances on the order of a micron or less. Existing closed-form analysis of the diffusion channel impulse response generally assumes that the transmitter is a point source. In this paper, channel impulse responses are derived for spherical transmitters with either a passive or absorbing receiver. The derived channel impulse responses are in closed-form for a one-dimensional environment and can be found via numerical integration for a three-dimensional environment. The point transmitter assumption (PTA) is formally defined so that its accuracy can be measured in comparison to the derived spherical transmitter impulse responses. The spherical transmitter model is much more accurate than the PTA when the distance between a transmitter and its receiver is small relative to the size of the transmitter. The derived results are verified via microscopic particle-based simulations using the molecular communication simulation platform AcCoRD (Actor-based Communication via Reaction-Diffusion). A spherical transmitter variation where molecules are released from the surface of a solid sphere is also considered via simulation.