Effective inter-symbol interference mitigation with a limited amount of enzymes in molecular communications

In molecular communication via diffusion (MCvD), the inter-symbol interference (ISI) is a well-known severe problem that deteriorates both data-rate and link reliability. ISI mainly occurs because of the slow and highly random propagation of the messenger molecules, which causes the emitted molecules from the previous symbols to interfere with molecules from the current symbol. An effective way to mitigate the ISI is using enzymes to degrade undesired molecules. Prior work on ISI mitigation by enzymes has assumed an infinite amount of enzymes randomly distributed around the molecular channel. Taking a different approach, this paper assumes an MCvD channel with a limited amount of enzymes. The main question this paper addresses is how to deploy these enzymes in an effective structure so that ISI mitigation is maximized. To find an effective MCvD channel environment, this study considers optimization of the shape of the transmitter node, the deployment location and structure, the size of the enzyme deployed area, and the half-lives of the enzymes. It also analyzes the dependence of the optimum size of the enzyme area on the distance and half-life. Lastly, the paper yields interesting results regarding the actual shape of the enzyme region itself.