Energy Allocation for Multi-User Cooperative Molecular Communication Systems in the Internet of Bio-Nano Things

TL;DR

This work addresses energy-constrained cooperative molecular communication in IoBNT by modeling imperfect transmitters built from two reservoirs per transmitter and moving molecules between reservoirs to create concentration differences for MoSK signaling. The authors derive an energy-cost model $E_{u_k}$ and formulate a BER-minimization problem under a total energy constraint $E_{ ext{total}}$ and BER thresholds, solving it analytically for $K=2$ and with a genetic algorithm for $K>2$. The key contributions include a closed-form optimal energy split $\rho=0.5$ for two symmetric transmitters, a GA-based approach for larger multi-user cases, and Monte Carlo simulations validating improved BER under energy-aware allocation. The results reveal a thermodynamic tradeoff between reservoir size and BER, offering design guidance for energy-limited IoBNT deployments and highlighting avenues for channel-aware optimization in future work.

Abstract

Cooperative molecular communication (MC) is a promising technology for facilitating communication between nanomachines in the Internet of Bio-Nano Things (IoBNT) field. However, the performance of IoBNT is limited by the availability of energy for cooperative MC. This paper presents a novel transmitter design scheme that utilizes molecule movement between reservoirs, creating concentration differences through the consumption of free energy, and encoding information on molecule types. The performance of the transmitter is primarily influenced by energy costs, which directly impact the overall IoBNT system performance. To address this, the paper focuses on optimizing energy allocation in cooperative MC for enhanced transmitter performance. Theoretical analysis is conducted for two transmitters. For scenarios with more than two users, a genetic algorithm is employed in the energy allocation to minimize the total bit error rate (BER). Finally, numerical results show the effectiveness of the proposed energy allocation strategies in the considered cooperative MC system.

Figures (7)

• Figure 1: A depiction of the cooperative communication system with the multi-user scenario. The users communicate with the receiver by releasing different types of molecules.
• Figure 2: A depiction of the imperfect transmitter. $k_1$ molecules are filled circles, while $k_2$ molecules are unfilled circles. Both the low reservoir and high reservoir are filled with $k_1$ and $k_2$ molecules. The model is inspired by the Maxwell's Demon thought experiment leff2002maxwell.
• Figure 3: The total BER at the transmitter for $u_1$ and $u_2$, where the number of molecules in the reservoirs are both $12\times10^8$.
• Figure 4: The total BER at the transmitter for $u_1$ and $u_2$, where the number of molecules in the reservoirs are $12\times10^8$ and $16\times10^8$, respectively.
• Figure 5: The total BER at the transmitter varies with $\rho$ under different numbers of molecules in the reservoirs. The number of transmitted molecules $N_m=5\times10^4$.