Multiple user and channel interference reduction methods for molecular communication via diffusion systems

Abstract

Molecular Communication via Diffusion (MCvD) is a very efficient way of com municating at the nano-scale, due to its simplicity and low energy cost. However, MCvD systems are subject to severe inter-symbol interference which inhibits high data rates. Overall interference is exacerbated when multiple nano-machines are connected to one another. Stemming from the need to establish good schemes to combat both these sources of interference, the thesis revolves around the idea of incorporating a full communication frame inside a molecule’s inner chemical structure. Inspired by the frame structure in traditional networks, the molecule frame consists of an overhead of frame identifier bits, and an information bearing payload. Using the frame identifier bits in a cyclic manner is found to combat the inter-symbol interference very effec tively, since it exponentially increases the time interval between cycles. However, due to the constraint on the energy consumption per bit, having a longer overhead causes to transmit fewer molecules per transmission, since it decreases the length of the payload. This, in turn, makes the received signal more noisy. Since the frame length is fixed due to the messenger molecule’s chemical structure, a trade-off between the lengths of the overhead and payload arises, which suggests there is an optimal allocation between them. By finding the optimal allocation point, high data rates while preserving low error rates can be achieved. Furthermore, by attaching a header in front of the frame molecules, destination addressing can be provided, and interference among different receivers can be eliminated by creating orthogonal channels between the receivers.