Receiver Nanomachine Research Articles

Joint Synchronization and Range Estimation With Correlated Arrival Times in Molecular Communication Networks

Time synchronization is needed in information exchange and collaboration among nanomachines for molecular communication networks. The time of arrival-based synchronization method requires the range information between the transmitter nanomachine (TN) and the receiver nanomachine (RN) in order to improve the accuracy of clock synchronization. The range information between the nanomachines helps to choose the optimal transmission rate. In contrast to the existing methods, this article proposes a joint clock offset and range estimation with correlated arrival times based on the maximum likelihood estimator. The RN uses the molecules' transmission and correlated arrival times to estimate the clock offset and range between the TN and RN. Even with correlated arrival times, the individual clock offset estimation performance is comparable to independent arrival times performance. Notably, the joint estimation problem with correlated arrival times is generic and realistic for molecular applications.

A Survey for Possible Technologies of Micro/Nanomachines Used for Molecular Communication Within 6G Application Scenarios

The Internet of bio-nanothings (IoBNT) is one of the potential application scenarios in the 6th generation (6G) mobile network, which envisions the interaction between biological cells or nanodevices and the Internet. Molecular communication (MC) may offer an appropriate communication method for the nanodevices using chemical molecules as the information carriers. However, due to the complexity of experiments and insufficient interdisciplinary cooperation, MC study mainly focuses on theoretical research, which seriously hinders the MC’s advancement and further applications. Therefore, it is crucial to explore methods for constructing transmitter and receiver nanomachines to realize practical MC systems. Based on the research progress of micro/nanomachines (MNMs) in recent years, this paper summarizes the possible technologies for implementing MNMs used for MC systems within 6G application scenarios.

Feedback-Controlled Adaptive Signal Detection Scheme for Diffusion-Based Molecular Communication Systems

This paper proposes a feedback-controlled adaptive method for detecting signals in diffusion-based molecular communication (MC) systems. Signal detection via a receiver nanomachine is a critical challenge for the exchange of information in MC systems. Incorrect estimations or small errors in signal detection can lead to high data detection errors. Existing methods for improving detection performance require high time costs or computational complexity. This paper proposes a simple and practical method that enables receiver nanomachines to automatically estimate signal detection times according to the measured molecular concentrations and weighted feedback errors. The proposed method adjusts the detection time even when the initial parameter values of the system are unknown to the receiver nanomachines. Simulations were performed to evaluate the bit error rate performance of the proposed and existing methods in terms of different data rates, transmission distances, and estimation error lengths under different initial conditions. The simulation results reveal that the implementation of the proposed method is simpler and demonstrates superior performance compared with that of existing methods.

Channel Characterization and Performance of a 3-D Molecular Communication System With Multiple Fully-Absorbing Receivers

Molecular communication (MC) can enable the transfer of information between nanomachines using molecules as the information carrier. In MC systems, multiple receiver nanomachines often co-exist in the same communication channel to serve common or different purposes. However, the analytical channel model for a system with multiple fully absorbing receivers (FARs), which is significantly different from the single FAR system due to the mutual influence of FARs, does not exist in the literature. The analytical channel model is essential in analyzing systems with multiple FARs, including MIMO, SIMO, and cognitive molecular communication systems. In this work, we derive an analytical expression for the hitting probability of a molecule emitted from a point source on each FAR in a diffusion-based MC system with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$N$ </tex-math></inline-formula> FARs. Using these expressions, we derive the channel model for a SIMO system with a single transmitter and multiple FARs arranged in a uniform circular array (UCA). We then analyze the communication performance of this SIMO system under different cooperative detection schemes and develop several interesting insights.

Molecule Harvesting Transmitter Model for Molecular Communication Systems

This paper develops mathematical models for molecule harvesting transmitters in diffusive molecular communication (MC) systems. In particular, we consider a communication link consisting of a spherical transmitter nano-machine and a spherical receiver nano-machine suspended in a fluid environment. The transmitter and the receiver exchange information via signaling molecules. The transmitter is equipped with molecule harvesting units on its surface. Signaling molecules which come into contact with the harvesting units may be re-captured by the transmitter. For this system, we derive closed-form expressions for the channel impulse response and harvesting impulse response. Furthermore, we extend the harvesting transmitter model to the case of continuous signaling molecule release. In particular, we derive closed-form expressions for the average received signal at the receiver and the average harvested signal at the transmitter for different temporal release rates namely, constant, linearly increasing, and linearly decreasing release rates. Finally, we validate the accuracy of the derived mathematical expressions via particle-based simulations.

Improving Reliability Performance of Molecular Communication Based on Drift Diffusion with Ratio Detection Algorithm

Reliability is a vital issue in the area of communication. In this paper, we particularly investigate the reliability issue for molecular communication based on drift diffusion (MCD2). Since molecules easily accumulate in the channel to produce strong internal symbol interference (ISI), the receiver nanomachine will generate high bit error rate (BER) for the process of decode information. Based on this problem, on the premise of considering channel diffusion noise and ISI noise, the expression of channel BER is deduced to analyze reliability. Then a ratio detection algorithm (RDA) is proposed to reduce BER to improve the reliability performance that enables the receiver nanomachine to adapt the channel condition. Furthermore, an expression of signal to interference plus noise ratio is defined in numerical simulation to verify our goal with different parameters, as well as with the adoption of RDA. The results indicate that the performance of RDA in reducing BER works well in general case in improving reliability performance for MCD2.

TDMA-MTMR-Based Molecular Communication With Ligand-Binding Reception

Multiple access-based molecular communication (MC) is an important way to implement MC nanonetworks for the Internet of Bio-Nano Things. In this letter, we propose a framework for time division multiple access (TDMA)-based MC by considering multiple-type transmission multiple-type reception (MTMR) for a system with multiple transmitter nanomachines and one receiver nanomachine (RN) which is non-ideal and has a switching delay. The reception process is based on ligand-binding reception. We study the drug release management approaches by minimizing the error probability. Besides, we propose a metric to find signal-to-interference ratio based on the channel memory. Analytical results, which are verified by the simulation, show that the TDMA-MTMR MC outperforms the state-of-the-art TDMA framework.

Impacts of Unintended Nanomachine in Diffusion-Based Molecular Communication System

The effect of unintended nanomachine (UN) on the performance of a 3-dimensional (3-D) diffusive point-to-point molecular communication system is investigated in this article. To analyze the impacts of the presence of UN, two different scenarios are considered. In the first scenario, UN is considered as an unintended transmitter nanomachine (UTN). The expression for arrival probability of molecules received at the spherical absorbing receiver, considering exponential molecular degradation, is obtained. Moreover, this scenario is analyzed in terms of average probability of error (APoE) and maximum achievable rate (MAR), with and without Genie-aided assumptions. Further, in the second scenario, wherein we consider UN as a unintended receiver nanomachine (URN), the system is analyzed in terms of information leakage and maximum achievable secrecy rate (MASR). In second scenario, we consider two different models to find the arrival probability of molecules at the intended receiver nanomachine (IRN). In the first model, independence of the particle death in URN and IRN is assumed, and in second model, mutual influences of URN and IRN on each other are assumed. Moreover, in both the scenarios, to optimize the system performance, an optimal detector is used. In the end, the derived analytical expressions are verified through particle-based and Monte-Carlo simulations.

Performance analysis of diffusion-based decode-and-forward relay with depleted molecule shift keying

The distance-decay effect of molecular signals makes communication range a major challenge for diffusion-based Molecular Communication (MC). To solve this problem, the intermediate nano-machine is deployed as a relay between the transmitter and its intended receiver nano-machines. In this work, we employ the Depleted Molecule Shift Keying (D-MoSK) to model a Decode-and-Forward (DF) relay communication scheme. The closed-form expression of Bit Error Rate (BER) for the concerned DF relay with D-MoSK is derived. Meanwhile, the maximum a posteriori probability, minimum error probability, and maximum likelihood schemes are formulated for data detection. The relationships between BER and other key parameters, including the number of released molecules, receiving radius, and relay position, are investigated in detail. Simulation results show that the proposed scheme can improve communication reliability significantly. Moreover, the performance gain can be maximized by optimizing the position of the relay and the receiving radius.

Multiple-Type Transmission Multiple-Type Reception Framework on Molecular Communication

In this letter, we propose a new multiple-input multiple-output (MIMO) molecular communication (MC) system where multiple types of molecules are utilized for transmission and reception of information. We call the proposed framework multiple-type transmission multiple-type reception (MTMR). The receiver nanomachines in the proposed scheme are based on the ligand receptors. For the bidirectional communication between the nanomachines, we consider two-way MC. We also obtain the bit error rate (BER) of the system, and an optimization problem is formulated to minimize BER by optimizing the drug dosage for designing a drug release mechanism. As numerical analysis shows, the BER of MIMO-MTMR in MC is minimized to 10−6 by considering the budget of molecules as 5000 for each transmitter. Furthermore, MIMO-MTMR outperforms single-type transmission single-type reception MIMO from the BER performance point of view as discussed in the numerical analysis.

Energy efficiency analysis of multi-hop mobile diffusive molecular communication

Diffusive molecular communication (DMC), in which molecules are used to deliver information in diffusion channel, is one of the most prominent systems in nanonetworks. In particular, the research on end-to-end mobile DMC system is even more challenging. In this paper, we investigate the energy efficiency of multi-hop mobile DMC system. First, the energy model for this system is proposed based on the mobilities of transmitter nanomachine (TN), relays and receiver nanomachine (RN). Then the mathematical expressions of total energy consumption and throughput are derived. Furthermore, the energy efficiency which is defined as the throughput per unit energy consumption is analyzed. Finally, the numerical results show that the parameters including the diffusion coefficients and velocities of mobile TN, relays and RN, the initial distance of each hop, the number of molecules emitted in each time slot by TN and relays, and each time slot duration have different impacts on the energy efficiency. How to set these system parameters can be used to provide guidelines for designing energy efficient multi-hop mobile DMC system.

Sum capacity analysis of mobile broadcast diffusive molecular communication

In this paper, we study the mobile broadcast diffusive molecular communication (DMC) system which is composed of one mobile transmitter nanomachine (TN) and multiple mobile receiver nanomachines (RNs). Considering that the reception event at each RN is different due to the time-varying impulse response of the mobile diffusion channel, in order to ensure that RNs can share the common information from TN with lower bit error probability (BEP), we add two fusion centers (FCs) in this system which are used to gather the information from RNs to make global decisions by using an N-out-of-K fusion rule. We propose three reporting schemes for the transmission between RNs and FCs including perfect reporting, different type of molecules and same type of molecules. Then the mathematical expressions of the optimal decision thresholds at RNs and FCs by using maximum-a-posterior detection method are obtained. On this basis, the BEP and sum capacity under the three reporting schemes are analyzed. Furthermore, the impacts of different parameters and reporting schemes on the performance of this system are evaluated and discussed by the numerical results. The setting of these parameters and reporting schemes can be used to provide the guideline for designing the mobile broadcast DMC system with lower BEP and higher sum capacity.

Maximising receiver response in molecular communication systems

In this Letter, the authors propose a novel approach to maximise the receiver response for molecular communication systems. The previously reported investigations for such systems are limited to a Dirac impulse and a rectangular pulse to transmit molecular information to a receiver nanomachine. Alternatively, they use a signal matched to the channel impulse response to maximise the molecular concentration delivered to a receiver nanomachine. They also derive an analytical expression for the probability of error. The simulation results confirm that the proposed approach is superior compared to the traditional works.

Spatial Nanomechanical Communications Based on State Transitions.

In this paper, we present a novel framework of a nanomechanical communication (NMC) system where nanomechanical (NM) systems can communicate using mechanical movements to encode and transfer information between a transmitter (TX) nanomachine and a receiver (RX) nanomachine. First, some unique features of the envisioned NMC system have been presented in contrast to traditional communications systems. It is demonstrated that the encoding of distinct repeatable movements or motions is the key to information transfer in an NMC system. Using a state transition framework, we identify rest states (RSs) and motional degrees of freedom (MDoF) as the two essential concepts that determine the transmission rate of an NMC system in the spatial domain in two different modes, namely, synchronous and asynchronous transmissions. While the synchronous transmission is found to achieve much higher transmission rate compared to the asynchronous transmission in the noise-free case, the asynchronous mode is less restrictive and may have wider applicability. A stochastic model is considered to incorporate the influence of thermal noise in the system. A closed-form expression of the symbol error rate (SER) and its bounds have been derived for a particular symbol of a synchronous sliding motion NMC system with MDoF = 2. Numerical results show a promising SER performance in support of developing an NMC system model for nanoscale communications networks.

Health monitoring scheme‐based Forster resonance energy transfer nanocommunications in the Internet of Biological Nanothings

SummaryIn this paper, a health monitoring approach for a targeted drug delivery (TDD) system taking into consideration the binding of drug to a target cell is proposed. The proposed scheme is mainly based on Forster resonance energy transfer (FRET) nanocommunications and the physical phenomenon such as protein–protein interactions in biological systems, in order to propose a molecular communication system with various forms for single and/or multiple ligand–receptor binding. Inspired by classical wireless communication system, the analysis of proposed scheme in terms of bit error rate (BER) and mutual information between the transmitter nanomachine (TN) and receiver nanomachine (RN) is presented. Subsequently, we are able to obtain a closed‐form expression for BER for the proposed scheme. The proposed scheme can be employed in the promising Internet of Biological Nanothings (IoBNT) paradigm. The numerical results reveal that the proposed scheme with multiple donors multiple acceptors system analogous to multiple input multiple output (MIMO) communication system is a superior scheme for transmission therapeutic drug information with achievable BER.

Nanomachine Localization in a Diffusive Molecular Communication System

The information-bearing molecules are used for communication among nanomachines in a diffusion-based molecular communication (DMC) system. The location of the nanomachine is needed for improving the performance of a DMC system. In the literature, only the distance between a transmitter nanomachine (TN) and a receiver nanomachine is estimated. In contrast, an iterative maximum likelihood estimate of the nanomachine location is computed herein. Notably, both the signal-dependent noise and intersymbol interference (ISI) effects are considered for nanomachine localization. Further, the nanomachine localization is performed, when the locations of the receiver nanomachine are both known and unknown. Additionally, the condition for the unique localizability of the TN and the bound of the proposed estimator are obtained. The results illustrate the effectiveness of the proposed method.

Low-Complexity Adaptive Signal Detection for Mobile Molecular Communication.

Currently, most of the researches in molecular communication (MC) domain focus on the static MC scenarios. However, some envisioned important MC applications require mobile MC system. The investigation on mobile MC, especially the signal detection of mobile MC is limited. This work considers the problem of signal detection for mobile MC scenarios where the receiver nano-machine performs random movement. Due to the random movement of the receiver, the channel impulse response (CIR) changes over time which makes the received signal stochastic and complicated. This further complicates the signal detection in mobile MC and leads to that the state-of-the-art signal detection schemes for static MC scenarios fail for the mobile MC scenarios. To solve this issue, an adaptive detection scheme has been proposed by our group previously, based on dynamic estimation of the stochastically varying distance between the transmitter and receiver and the reconstruction of CIR in each interval. However, its computational complexity is high. Limited capability of current nano-machines desire low-complexity detection algorithm. In this work, we further propose an adaptive detection scheme for mobile MC with a low computational complexity by utilizing the local convex property of the CIR. With on-off keying (OOK) modulation, the signal of symbol "1" presents local convex property while that of symbol "0" presents local concave property. The convexity extent varies with the stochastic distance. A simple indicator, local maximum convexity is proposed which adapts to the stochastic distance. By comparing the adaptive indicator with an adaptive threshold within each symbol interval, the signal is detected without the need to estimate the stochastically changing distance or to reconstruct the CIR. Therefore, the computational load is effectively reduced. Numerical simulations are performed to evaluate the proposed scheme. The results show that the proposed scheme achieves good detection accuracy with low computational complexity and it could be a promising detection scheme for mobile MC scenarios.

A Cross-Layer Approach for Optimization of MolCom Systems Toward the Internet of Bio-NanoThings

Inspired by conventional communication network protocols, a cross-layer approach for the optimization of nanonetwork-based molecular communication (MolCom) systems toward the Internet of Bio-NanoThings is presented in this study. According to the proposed molecular-layered architecture, a molecular link layer-based xor biomolecular switch adopts the transmission rate of a molecular frame for transmission in the next frame, based on the available molecular information in a physical layer. Owing to the MolCom environment dynamics, the frame transmission rate is optimized by computing the bond throughput and is efficiently processed at receiver nanomachines. The performance of the proposed cross-layer approach is modulated by adopting the enzymatic feedback signaling. Additionally, we develop the analysis of the proposed cross-layer approach by using queueing system in terms of molecular frame loss rate. The numerical results, such as the average time delay delivery of molecular frame and the tolerant traffic rate, reveal that the proposed cross-layer approach improves the nanonetwork-based MolCom system considerably.

Optimal Transmitted Molecules and Decision Threshold for Drift-Induced Diffusive Molecular Channel With Mobile Nanomachines.

We study a drift-induced diffusive mobile molecular communication system where source, destination and cooperative nanomachines follow the one-dimensional Brownian motion. For information exchange from source nanomachine to receiver nanomachine, both direct and decode-forward (DF) relay-assisted cooperative paths are considered. The closed-form expressions for the probabilities of detection and false alarm are derived at the cooperative and destination nanomachines considering the multiple-source interference (MSI) and the inter-symbol-interference (ISI). The closed-form expressions for end-to-end average probability of error, and maximum achievable rate are also obtained. Moreover, to achieve minimum expected probability of error the optimum number of molecules to be transmitted from transmitter and optimal detection threshold in receiver nanomachine are found. The analytical expressions are validated through particle-based and Monte-Carlo simulation methods.

Signal reconstruction in diffusion‐based molecular communication

AbstractMolecular communication (MC) is an important nanoscale communication paradigm, which is employed for the interconnection of the nanomachines (NMs) to form nanonetworks. A transmitter NM (TN) sends the information symbols by emitting molecules into the transmission medium and a receiver NM (RN) receives the information symbols by sensing the molecule concentration. In this paper, a model of how an RN measures and reconstructs the molecular signal is proposed. The signal around the RN is assumed to be a Gaussian random process instead of the less realistic deterministic approach. After the reconstructed signal is derived as a doubly stochastic poisson process, the distortion between the signal around the RN and the reconstructed signal is derived as a new performance parameter in MC systems. The derived distortion, which is a function of system parameters such as RN radius, sampling period, and the diffusion coefficient of the channel, is shown to be valid by employing random walk simulations. Then, it is shown that the original signal can be satisfactorily reconstructed with a sufficiently low level of distortion. Finally, optimum RN design parameters, namely, RN radius, sampling period, and sampling frequency, are derived by minimizing the signal distortion. The simulation results reveal that there is a trade‐off among the RN design parameters which can be jointly set for a desired signal distortion.