Performance Analysis and ISI Mitigation with Imperfect Transmitter in Molecular Communication

TL;DR

This work analyzes molecular communication with an imperfect transmitter realized by two reservoirs containing mixed signaling molecules due to finite purification energy $E$, which induces ISI. It derives the relation $m = \sqrt{ \frac{c n}{2 k T_e} E }$ and shows how reservoir fractions become $c_L = c - \frac{m}{n_L}$ and $c_H = c + \frac{m}{n_H}$, linking energy cost to transmitter impurity. A ratio-based Neyman-Pearson detector is proposed to mitigate ISI, with BER analyzed under Gaussian approximations for the diffusion channel and counting noise. Simulations confirm an energy–BER tradeoff: higher energy cost yields larger reservoir separation and improved BER, though with diminishing returns, and the proposed detector outperforms conventional counting-based approaches.

Abstract

In molecular communication (MC), molecules are released from the transmitter to convey information. This paper considers a realistic molecule shift keying (MoSK) scenario with two species of molecule in two reservoirs, where the molecules are harvested from the environment and placed into different reservoirs, which are purified by exchanging molecules between the reservoirs. This process consumes energy, and for a reasonable energy cost, the reservoirs cannot be pure; thus, our MoSK transmitter is imperfect, releasing mixtures of both molecules for every symbol, resulting in inter-symbol interference (ISI). To mitigate ISI, the properties of the receiver are analyzed and a detection method based on the ratio of different molecules is proposed. Theoretical and simulation results are provided, showing that with the increase of energy cost, the system achieves better performance. The good performance of the proposed detection scheme is also demonstrated.

Figures (9)

• Figure 1: A depiction of the communication system. $\rm{A}$ molecules are filled circles, while $\rm{B}$ molecules are unfilled circles (cf. eckford2018thermodynamic). Both the low reservoir and high reservoir are filled with $\rm{A}$ and $\rm{B}$ molecules. By moving B molecules from the low reservoir to the high reservoir, a difference in the concentrations of A and B molecules is created between the two reservoirs.
• Figure 2: The number of moved molecules versus energy cost under $c = 0.5$.
• Figure 3: The number of moved molecules versus energy cost under $n_L = n_H =5 \times 10^8$.
• Figure 4: The BER versus the detection threshold $\gamma$.
• Figure 5: The BER versus the initial fraction of $\rm{B}$ molecules in the low reservoir $c_L$.