Semantic Information in MC: Chemotaxis Beyond Shannon

The recently emerging molecular communication (MC) paradigm intents to leverage communication engineering tools for the design of synthetic chemical communication systems. These systems are envisioned to operate on nanoscale and in biological environments, such as the human body, and catalyze the emergence of revolutionary applications in the context of early disease monitoring and drug targeting. However, while a plethora of theoretical (and more recently also more and more practical) MC system designs have been proposed over the past years, some fundamental questions remain open, hindering the breakthrough of MC in real-world applications. One of these questions is: What is a useful measure of information in the context of MC-based applications? While most existing works in MC build upon the concept of syntactic information as introduced by Shannon, in this paper, we explore the framework of semantic information as introduced by Kolchinsky and Wolpert for the information theoretical analysis of a natural MC system, namely bacterial chemotaxis. Exploiting the computational modeling tool of agent-based modeling (ABM), we are able to demonstrate that the semantic information framework can provide a useful information theoretical framework for quantifying the information exchange of chemotactic bacteria with their environment. In particular, we show that the measured semantic information provides a useful measure of the ability of the bacteria to adapt to and survive in a changing environment. Encouraged by our results, we envision that the semantic information framework can open new avenues for developing theoretical and practical MC system designs and in this way help to unleash the full potential of MC for complex adaptive systems-based nanoscale applications.