Molecular MIMO: From Theory to Prototype (1603.03921v1)

Abstract: In diffusion-based molecular communication, information transport is governed by diffusion through a fluid medium. The achievable data rates for these channels are very low compared to the radio-based communication system, since diffusion can be a slow process. To improve the data rate, a novel multiple-input multiple-output (MIMO) design for molecular communication is proposed that utilizes multiple molecular emitters at the transmitter and multiple molecular detectors at the receiver (in RF communication these all correspond to antennas). Using particle-based simulators, the channel's impulse response is obtained and mathematically modeled. These models are then used to determine inter-link interference (ILI) and inter-symbol interference (ISI). It is assumed that when the receiver has incomplete information regarding the system and the channel state, low complexity symbol detection methods are preferred since the receiver is small and simple. Thus four detection algorithms are proposed---adaptive thresholding, practical zero forcing with channel models excluding/including the ILI and ISI, and Genie-aided zero forcing. The proposed algorithms are evaluated extensively using numerical and analytical evaluations.

• The paper "Molecular MIMO: From Theory to Prototype" explores applying MIMO principles to molecular communications, proposing novel detection algorithms and a prototype to address slow data rates and interference.
• Numerical simulations demonstrate that the proposed molecular MIMO approach significantly reduces inter-symbol and inter-link interference, improving bit error rates compared to single-input single-output systems.
• A practical macro-scale tabletop testbed validated the theory, achieving a 1.7-fold increase in data transmission rates over SISO systems and showing the practical viability of molecular MIMO.

Molecular MIMO: Advancements in Molecular Communications

The development of molecular communications promises to establish a transformative mode of communication at micro and nano scales, as evidenced by the comprehensive exploration of molecular multiple-input multiple-output (MIMO) communication systems presented in the paper "Molecular MIMO: From Theory to Prototype." This paper offers a significant contribution to the field of molecular communication by addressing inherent challenges such as low data rates due to slow diffusion processes and interference issues, including inter-symbol interference (ISI) and inter-link interference (ILI) inherent in molecular communication channels.

Molecular MIMO communication leverages multiple molecular emitters and receivers, akin to antennas in conventional radio frequency (RF) MIMO systems, to potentially enhance data rates in diffusion-based systems. The research presented in this paper introduces novel detection algorithms tailored to the molecular MIMO environment, characterized by a simple receiver design constrained by incomplete system and channel state information. Notably, four algorithms were devised to address symbol detection challenges: adaptive thresholding, practical zero forcing with and without consideration of ILI and ISI, and Genie-aided zero forcing. These algorithms are evaluated through comprehensive numerical and analytical techniques, demonstrating substantial improvements in bit error rates, a critical performance metric in communication systems.

Significant numerical results gleaned from extensive simulations reveal that the innovative MIMO approach noticeably reduces inter-symbol and inter-link interference, crucial for increasing data rates in molecular communication systems. Furthermore, the theoretical models for channel impulse response formulated in this paper incorporate both ILI and ISI, providing a structured methodology to evaluate interference and detect transmitted symbols effectively. The mathematical rigor in establishing performance benchmarks through bit error rate (BER) analysis underscores the distinguishing capability of the proposed MIMO configurations in molecular communication systems.

Practically, the implications of these findings are noteworthy. The introduction of a macro-scale tabletop testbed represents an empirical validation of theoretical constructs, bridging conceptual insights with real-world applications. By implementing detection algorithms on this testbed, the authors have successfully demonstrated the practical viability of molecular MIMO systems, recording a 1.7-fold increase in data transmission rates over single-input single-output (SISO) systems. This empirical evidence reinforces the potential of molecular communications to eventually support high-efficiency data transmission networks at scales where traditional RF methods are untenable.

Theoretically, this work extends the knowledge of molecular communication systems by introducing mechanisms to model, predict, and mitigate interference in a MIMO setup. The channel modeling incorporating fitted non-linear functions provides a sophisticated and customizable approach, accommodating diverse environmental and topological parameters. The development of this model invites further exploration and experimentation, particularly in enhancing the accuracy of detections and optimizing system configurations for specific applications.

Looking forward, the progression of molecular communications, particularly in MIMO configurations, stands to influence diverse domains such as biological and chemical sensing networks, nanomedicine, and environmental monitoring. Continued innovation in this frontier promises to expand the utility of nanoscale communication, potentially enabling sophisticated, networked nanosystems capable of dynamic, adaptive interaction environments.

In summary, "Molecular MIMO: From Theory to Prototype" presents crucial advancements in the field of molecular communication, both theoretical and practical, laying the groundwork for future exploration and exploitation of molecular MIMO systems. Through rigorous modeling, simulation, and real-world testing, this work amplifies our understanding of molecular communication systems and propels us closer to their widespread application.