Molecule Harvesting Transmitter Model for Molecular Communication Systems

Abstract

This paper develops mathematical models for molecule harvesting transmitters in diffusive molecular communication (MC) systems. In particular, we consider a communication link consisting of a spherical transmitter nano-machine and a spherical receiver nano-machine suspended in a fluid environment. The transmitter and the receiver exchange information via signaling molecules. The transmitter is equipped with molecule harvesting units on its surface. Signaling molecules which come into contact with the harvesting units may be re-captured by the transmitter. For this system, we derive closed-form expressions for the channel impulse response and harvesting impulse response. Furthermore, we extend the harvesting transmitter model to the case of continuous signaling molecule release. In particular, we derive closed-form expressions for the average received signal at the receiver and the average harvested signal at the transmitter for different temporal release rates namely, constant, linearly increasing, and linearly decreasing release rates. Finally, we validate the accuracy of the derived mathematical expressions via particle-based simulations.

Analysis of Receiver Covered by Heterogeneous Receptors in Molecular Communications

“…is the ratio of the area of the ith receptor to the area of the TX surface, and h e (t) is the total hitting rate of molecules on the TX membrane which is given by (10). We recall that A is the ratio of the total area of receptors to the area of the TX surface, as mentioned in Section II-A3.…”

“…Then, P (t) can be obtained as P (t) = (f c (t) −h e (t)) * P u (t). By substituting (10) into this expression, we obtain (21).…”

“…This mechanism is essential for synaptic communication as it enables the recycling of neurotransmitters and regulates the duration of signal transmission. Inspired by this biological example, a recent study [10] developed a spherical molecule harvesting TX model, where the membrane is equipped with receptors capable of reacting with information molecules. Specifically, the authors considered a homogeneous TX surface and assumed that an infinite number of receptors cover the entire TX surface or a finite number of receptors of identical sizes are uniformly distributed over the TX surface.…”

“…Specifically, the authors considered a homogeneous TX surface and assumed that an infinite number of receptors cover the entire TX surface or a finite number of receptors of identical sizes are uniformly distributed over the TX surface. However, the analysis in [10] did not address the practical case where receptors on the TX surface can have different sizes and arbitrary locations.…”

“…To explicitly examine the impact of the considered TX model on performance, we investigate the channel impulse response (CIR) for a transparent RX, accounting for the possibility of molecule degradation during propagation from the TX to the RX. In this context, we note that the analysis in [10] is not applicable when considering heterogeneous boundary conditions and vesicle-based molecule release at the TX. Furthermore, we incorporate NFM at the TX, assuming that the TX stops releasing molecules after a specific time period.…”