Capacity Analysis of Molecular Communications with Ratio Shift Keying Modulation

TL;DR

This paper analyzes the capacity of molecular communication systems using Ratio Shift Keying (RSK) modulation, showing its potential advantages over traditional methods like CSK under certain conditions.

Contribution

It provides an information-theoretic capacity analysis of RSK modulation in molecular communications and compares its performance with existing techniques.

Findings

RSK can outperform CSK in power-limited scenarios.

RSK offers advantages under time-varying channel conditions.

Numerical results demonstrate the effectiveness of RSK based on ligand similarity and receptor count.

Abstract

Molecular Communications (MC) is a bio-inspired communication technique that uses molecules to encode and transfer information. Many efforts have been focused on developing new modulation techniques for MC by exploiting distinguishable properties of molecules. In this paper, we investigate a particular modulation scheme where the information is encoded into the concentration ratio of two different types of molecules. To evaluate the performance of this so-called Ratio Shift Keying (RSK) modulation, we carry out an information theoretical analysis and derive the capacity of the end-to-end MC channel where the receiver performs ratio estimation based on ligand-receptor binding statistics in an optimal or suboptimal manner. The numerical results, obtained for varying similarity between the ligand types employed for ratio-encoding, and number of receptors, indicate that the RSK can outperform the concentration shift keying (CSK) modulation, the most common technique considered in literature, when the transmitter is power-limited. The results also indicate the potential advantages of RSK over other modulation methods under time-varying channel conditions, when the effects of the dynamic conditions are invariant to the type of the molecules.