On Effect of Different Sequence Distributions on ISI in an MCvD System

Abstract

In a Molecular-Communication-via-Diffusion (MCvD) channel, the molecules follow a simple Brownian motion that leads to an irregular arrival of the molecules at the receiver and introduces Inter-Symbol-Interference (ISI) in the channel. In this work, we have used different sequence distributions to analyze the effect of ISI in an MCvD channel. It has been shown that the ISI strictly depends on the location of bit-1s in the sequence, and accordingly, the expected ISI has been computed for all the proposed sequences based on the bit-1 positions in the sequence. We have also derived an upper bound on the expected ISI for the proposed sequences. We have shown that One-at-Starting-Position (OSP) sequence shows the best performance among all the proposed sequence distributions, with the expected ISI converging to a constant value. Simulation results also corroborate that the OSP sequence provides the lowest ISI in an MCvD channel compared to other codes studied in the literature.