Improving the capacity of molecular communication using enzymatic reaction cycles

TL;DR

This paper demonstrates that enzymatic reaction cycles can enhance the capacity of diffusion-based molecular communication links by increasing channel gain and reducing noise, especially when the substrate amount is increased.

Contribution

It introduces a novel analysis of enzymatic reaction cycles' impact on molecular communication capacity using singular perturbation techniques.

Findings

Enzymatic reaction cycles increase channel gain.

They reduce noise in the communication link.

Capacity improves with more substrate in the cycle.

Abstract

This paper considers the capacity of a diffusion-based molecular communication link assuming the receiver uses chemical reactions. The key contribution is we show that enzymatic reaction cycles, which is a class of chemical reactions commonly found in cells consisting of a forward and a backward enzymatic reaction, can improve the capacity of the communication link. The technical difficulty in analysing enzymatic reaction cycles is that their reaction rates are nonlinear. We deal with this by assuming that the amount of certain chemicals in the enzymatic reaction cycle is large. In order to simplify the problem further, we use singular perturbation to study a particular operating regime of the enzymatic reaction cycles. This allows us to derive a closed-form expression of the channel gain. This expression suggests that we can improve the channel gain by increasing the total amount of substrate in the enzymatic reaction cycle. By using numerical calculations, we show that the effect of the enzymatic reaction cycle is to increase the channel gain and to reduce the noise, which results in a better signalto- noise ratio and in turn a higher communication capacity. Furthermore, we show that we can increase the capacity by increasing the total amount of substrate in the enzymatic reaction cycle.