Transmission Rate Control for Molecular Communication among Biological Nanomachines

TLDR

Molecular communication involves bio‑nanomachines sending molecules that propagate and are chemically reacted by receivers, but if transmission exceeds receiver reaction rates, excess molecules degrade or diffuse, reducing efficiency. This paper frames transmission‑rate control in molecular communication as an optimization problem to address throughput and efficiency trade‑offs. The authors model high‑rate transmission, derive an upper‑bound expression for throughput and efficiency, and design two feedback‑based control schemes—negative and positive feedback—to autonomously adjust rates. Numerical results identify optimal transmission rates that maximize throughput and efficiency, reveal a trade‑off across rates, and demonstrate that the proposed feedback schemes offer practical guidelines for developers.

Abstract

In this paper, we discuss issues concerned with transmission rate control in molecular communication, an emerging communication paradigm for bio-nanomachines in an aqueous environment. In molecular communication, a group of bio-nanomachines acting as senders transmit molecules, the molecules propagate in the environment, and another group of bio-nanomachines acting as receivers chemically react to the molecules propagating in the environment. In the model of molecular communication considered in this paper, senders may transmit molecules at a high rate to accelerate the receiver reactions or to increase the throughput. However, if the senders transmit molecules faster than the receivers react, the excess molecules remain in the environment and eventually degrade or diffuse away, which results in loss of molecules or degradation in efficiency. Such a potential issue associated with throughput and efficiency is in this paper discussed as an optimization problem. A mathematical expression for an upper-bound on the throughput and efficiency is first derived to provide an insight into the impact of model parameters. The optimal transmission rates that maximize the throughput and efficiency are then numerically calculated and presented, and throughput and efficiency are shown to be in trade-off relationships in a wide range of transmission rates. Further, two classes of feedback-based transmission rate control schemes are designed for autonomous bio-nanomachines to dynamically control their transmission rates, respectively based on negative and positive feedback from the receivers. The numerical evaluation of the two transmission rate control schemes is then shown to provide useful guidelines for application developers to satisfy their design goals.