On the Capacity of Level and Type Modulation in Molecular Communication with Ligand Receptors

TL;DR

This paper compares the capacity of level-based and type-based molecular communication strategies using ligand receptors, deriving bounds and analyzing receptor blocking effects to understand their trade-offs.

Contribution

It introduces a capacity analysis framework for ligand receptor communication considering both level and type modulation, including bounds and receptor blocking effects.

Findings

Type scenario can outperform level scenario under certain conditions

Derived upper and lower bounds on receptor capacity

Receptor blocking impacts communication capacity significantly

Abstract

In this paper, we consider the bacterial point-to-point communication problem with one transmitter and one receiver by considering the ligand receptor binding process. The most commonly investigated signalling model, referred to as the Level Scenario (LS), uses one type of a molecule with different concentration levels for signaling. An alternative approach is to employ multiple types of molecules with a single concentration level, referred to as the Type Scenario (TS). We investigate the trade-offs between the two scenarios for the ligand receptor from the capacity point of view. For this purpose, we evaluate the capacity using numerical algorithms. Moreover, we derive an upper bound on the capacity of the ligand receptor using a Binomial Channel (BIC) model using symmetrized Kullback-Leibler (KL) divergence. A lower bound is also derived when the environment noise is negligible. Finally, we analyse the effect of blocking of a receptor by a molecule of a different type, by proposing a new Markov model in the multiple-type signalling.