On the Impact of Time-Synchronization in Molecular Timing Channels

TL;DR

This paper analyzes the effects of time synchronization on molecular timing channels, comparing synchronized and asynchronous modulation schemes, and introduces a geometric power measure for stable distributions to evaluate system performance.

Contribution

It introduces a geometric power framework for stable distributions and compares synchronization schemes in molecular timing channels, highlighting performance trade-offs.

Findings

Synchronization significantly improves BER performance.

Using distinguishable particles in asynchronous schemes approaches synchronized performance.

The paper derives optimal detection rules for binary communication in these channels.

Abstract

This work studies the impact of time- synchronization in molecular timing (MT) channels by analyzing three different modulation techniques. The first requires transmitter-receiver synchronization and is based on modulating information on the release timing of information particles. The other two are asynchronous and are based on modulating information on the relative time between two consecutive releases of information particles using indistinguishable or distinguishable particles. All modulation schemes result in a system that relate the transmitted and the received signals through an additive noise, which follows a stable distribution. As the common notion of the variance of a signal is not suitable for defining the power of stable distributed signals (due to infinite variance), we derive an expression for the geometric power of a large class of stable distributions, and then use this result to characterize the geometric signal-to-noise ratio (G-SNR) for each of the modulation techniques. In addition, for binary communication, we derive the optimal detection rules for each modulation technique. Numerical evaluations indicate that the bit error rate (BER) is constant for a given G-SNR, and the performance gain obtained by using synchronized communication is significant. Yet, it is also shown that by using two distinguishable particles per bit instead of one, the BER of the asynchronous technique can approach that of the synchronous one.