Mobile Molecular Communication Research Articles

Classification of Diffusion Constants of Transmitter and Receiver and Distance Between Them Using Mobile Molecular Communication via Diffusion Model

Classification of Diffusion Constants of Transmitter and Receiver and Distance Between Them Using Mobile Molecular Communication via Diffusion Model

An Informer-Based Signal Sequence Detector for Mobile Molecular Communication

An Informer-Based Signal Sequence Detector for Mobile Molecular Communication

Detection and ISI mitigation in mobile molecular communication system for targeted drug delivery

This paper proposes a targeted drug delivery system based on mobile molecular communication (MMC). The system consists of a mobile transmitter and a mobile reactive receiver. The transmitter can sense the required drug concentration and send commands to the receiver for drug delivery in the extracellular fluid (ECF). The commands are sent in the form of bits and the received signal is prone to noise and inter-symbol interference (ISI). Hence, at the receiver, two detection techniques, differential amplitude detector (DAD) and differential energy detector (DED) with ISI mitigation are proposed for MMC. Manchester-coded bits are transmitted using modified concentration shift keying (MCSK). In the proposed detection mechanism, an adaptive threshold technique is used for estimating the number of signaling molecules using the maximum a posteriori probability (MAP) rule. Further in each bit interval, dynamic distance estimation, signal reconstruction, and ISI mitigation are performed. Particle-based simulation for reactive receiver is also carried out to validate the results. A low bit error rate (BER) in the MMC system signifies the promising performance of the drug delivery system.

Evaluation of Non-Coherent Signal Detection Techniques for Mobile Molecular Communication.

In recent years, there have been more and more research on molecular communication (MC). Because the deployment of mobile nanomachines may be required in some applications of MC, research on mobile MC has become a trend. The signal detection schemes for static MC are no longer applicable due to the time varying channel impulse response (IR), which is caused by the mobile characteristics of nanomachines. In this paper, a low complexity and non-coherent detection scheme is proposed for mobile scenario, which is based on the energy difference between two adjacent symbols. Most of the existing signal detection methods do not consider inter-symbol interference (ISI). Compared with those methods, the proposed scheme can achieve signal detection utilizing ISI without knowing channel state information (CSI). The bit error rate (BER) performance of the proposed method is investigated under different conditions through simulations. Besides, the influence of mobility features of nanomachines on the signal detection accuracy is also investigated in detail. The simulation results demonstrate that the BER performance of the proposed scheme outperforms the latest signal detection scheme for short-distance mobile MC system with high velocity. Consequently, the detection scheme proposed in this paper can reduce the influence of nanomachines' mobility and has the potential to be used in mobile MC systems.

Rescaled Brownian Motion of Molecules and Devices in Three-Dimensional Multiuser Mobile Molecular Communication Systems

This paper considers a three-dimensional anomalous-diffusive mobile molecular communication (MC) channel. Herein, the communicating devices, i.e., point transmitter (Tx) and passive receiver (Rx) can also move anomalously with the information-carrying molecule (ICM). In order to incorporate the anomalous diffusion phenomenon, the concept of rescaled-Brownian motion is explored. Two different scenarios, named point-to-point and multi-user MC systems, are considered for the analysis. First, considering the point-to-point scenario, the expressions for the channel impulse response (CIR) incorporating static and mobile Tx and Rx are derived. Further, the expressions for the peak time of CIR and the corresponding peak value are also derived. Furthermore, the point-to-point MC system is exploited in terms of bit-error-rate (BER), minimum BER, maximum mutual information, and throughput. A multi-user MC system is considered in the second scenario, and a molecular division multiple access (MDMA) method is used. The system is analyzed in terms of BER and throughput. Further, the system performance is optimized using two schemes known as min-max fairness for error probability and max-min fairness for throughput. Furthermore, we use best-to-best and best-to-worst assignment strategies to allocate different types of ICMs for each Rx. Subsequently, the optimal allocation for the number of ICMs is obtained when specific ICMs are assigned to all users/receivers for a two-user scenario. All the channel metrics are verified through particle-based and Monte-Carlo simulations.

An Extended Kalman Filter for Distance Estimation and Power Control in Mobile Molecular Communication

In this paper, we consider a mobile molecular communication (MC) system consisting of two mobile nanomachines, a transmitter and a receiver, propelled by a positive drift velocity and Brownian motion in a realistic blood-vessel-type flow regime. Considering the nonlinear movement of the nanomachines, an extended Kalman filter is employed to estimate the distance from the transmitter. Furthermore, based on the predicted distance, to keep the number of received molecules for bit 1 at a stable level, we employ power control on the number of transmitted molecules based on the distance between the transmitter and the receiver and the residual molecules in the channel from the previous transmission. Finally, the optimal detection threshold is obtained by minimizing the error probability. It is verified that a fixed optimal detection threshold can be effective for the power control scheme in the mobile MC. The bit error rate (BER) performance of our scheme is verified via simulation results.

Joint Optimizations of Relays Locations and Decision Threshold for Multi-Hop Diffusive Mobile Molecular Communication With Drift.

In this paper, we study diffusive multi-hop mobile molecular communication (MMC) with drift in one-dimensional channel by adopting amplify-and-forward (AF) relay strategy. Multiple and single molecules type are used in each hop to transmit information, respectively. Under these two cases, the mathematical expressions of average bit error probability (BEP) of this system based on AF scheme are derived. We implement joint optimization problem whose objective is to minimize the average BEP with (Q + 2) optimization variables including (Q + 1) -hop distance ratios and decision threshold. Q is the number of relay nodes. Furthermore, considering that more optimization variables result in higher computation complexity, we use efficient algorithm which is adaptive genetic algorithm (AGA) to solve the optimization problems to search the location of each relay node and the decision threshold at destination node simultaneously. Finally, the numerical results reveal that AGA has a faster convergence speed and it is more efficient with fewer iterations compared with Bisection algorithm. The performances of average BEP with optimal distance ratio of each hop and decision threshold are evaluated. These results can be used to design multi-hop MMC system with optimal optimization variables and lower average BEP.

Mobile Two-Way Molecular Communication via Diffusion Using Amplify-and-Forward and Analog Network Coding.

Mobile molecular communication via diffusion (MCvD) has attracted lots of attentions due to its time-varying channels. In this paper, we investigate a mobile two-way MCvD model, which consists of two mobile source nanomachines and a mobile relay nanomachine. The amplify-and-forward (AF) relaying and analog network coding (ANC) are utilized to implement the exchange of information between two source nanomachines in this model. To explore the performance of the mobile two-way MCvD system, we first adopt the depleted molecule shift keying (D-MoSK) modulation, and then the mathematical expressions of symbol error probability (SEP) and mutual information are derived by using AF and ANC scheme on the basis of maximum a posteriori (MAP) probability detection. Finally, we present the numerical and simulation results. Compared with the AF-No-ANC scheme which is without use of ANC scheme, the scheme of combining AF and ANC can significantly improve the performance of SEP and mutual information. Moreover, the D-MoSK modulation outperforms the molecule shift keying (MoSK) modulation for this mobile two-way MCvD system. In addition, we propose the evaluation and discussion about the impacts of several important parameters on the performance of this system. These results can be used to design mobile two-way MCvD system with lower SEP and higher mutual information.

Analysis and classification of the mobile molecular communication systems with deep learning

Analysis and classification of the mobile molecular communication systems with deep learning

How mobility of transmitter and receiver affects the communication quality

Nano-networks focused on communication of nano-sized devices (nanomachines) are a new communication concept, which is known as Molecular Communication (MC) in the literature. In this study, on the contrary to the literature, a mobile MC model is proposed in a diffusion environment by using 5 bits because it is known that besides the molecules, which transport information between the transmitter and receiver, the transmitter and receiver parts of the biological cells are mobile in the blood or any other fluid media. In this study, both the transmitter and the receiver can be chosen as mobile and/or fixed for some specific duties, such as drug delivery systems. Their mobility values can also be regulated separately for the proposed mobile MC model. The proposed model is analyzed for the different situations of the transmitter and receiver (fixed and/or mobile) by considering the fraction of the received molecules. Finally, the number of bits, the time step, and the bit duration are analyzed to find the best MC model. It is concluded that when the receiver and the transmitter are mobile, the distance between them changes, and finally, this affects the probability of the received molecules at the receiver.

Membrane Fusion-Based Transmitter Design for Static and Diffusive Mobile Molecular Communication Systems

This paper proposes a novel imperfect transmitter (TX) model, namely the membrane fusion (MF)-based TX, that adopts MF between a vesicle and the TX membrane to release molecules encapsulated within the vesicle. For the MF-based TX, the molecule release probability and the fraction of molecules released from the TX membrane are derived. Incorporating molecular degradation and a fully-absorbing receiver (RX), the channel impulse response (CIR) is derived for two scenarios: 1) Both TX and RX are static, and 2) both TX and RX are diffusion-based mobile. Moreover, a sequence of bits transmitted from the TX to the RX is considered. The average bit error rate (BER) is obtained for both scenarios, wherein the probability mass function (PMF) of the number of molecules absorbed in the mobile scenario is derived. Furthermore, a simulation framework is proposed for the MF-based TX, based on which the derived analytical expressions are validated. Simulation results show that a low MF probability or low vesicle mobility slows the release of molecules and reduces the molecule hitting probability at the RX. Simulation results also indicate the difference between the MF-based TX and an ideal point TX in terms of the inter-symbol interference (ISI).

Modulation and Signal Detection for Diffusive-Drift Molecular Communication with a Mobile Receiver

Molecular communication (MC), which allows nanomachines to communicate with each other by using chemical molecules, is considered to be a promising method for communications in liquid environment. Available works on MC mainly focus on modulation and signal detection schemes for MC systems with fixed nanomachines, i.e., fixed molecular communication (FMC) systems. However, the more complex systems with mobile nanomachines (i.e., mobile molecular communication (MMC) systems) have been largely unexplored. This paper considers a MMC system with a fixed transmitter and a mobile receiver communicating over diffusive-drift channels of a limited boundary. We first propose a new modulation scheme to address the issue of misalignment in the signal detection of MMC systems by adopting three types of molecules in the signal modulation and modulating the transmitted signals into blocks with equal length to avoid the transferring of a signal error in the current block on the signal detection in other blocks. We then propose a new signal detection scheme of the MMC systems by calculating the distance between the transmitter and the receiver based on a distance prediction method and detecting signals at the receiver based on the decided adaptive concentration threshold in each time interval. To verify the efficiency of our proposed scheme, we then conducted extensive simulations by the Monte Carlo simulation, and comparisons are also made among our proposed schemes, a well-known fixed threshold signal detection scheme, the CATD scheme, the PAD scheme, and a low complexity signal detection scheme for MMC systems in terms of the BER (bit error rate). Results show that our proposed schemes can outperform these schemes regarding the BER.

Particle-Based Simulation of the Differential Detectors for Mobile Molecular Communication

In this work, a particle-based simulation of two differential detectors for a reactive receiver in mobile molecular communication (MMC) is presented. The received signal is filtered and used for detection. On-off keying (OOK) is used as the modulation in both schemes. The detector in first scheme finds two-time instants in the filtered signal to maximize absolute concentration difference within the same bit duration. Then the concentration difference is used as the decision metric. The second scheme uses Manchester coding at the transmitter where the bit-0 and bit-1 are represented as the symbol [0 1] and symbol [1 0] respectively. The difference between the peak values of filtered signals in successive bit durations is used as the decision metric. Correlation between the analytical signal and particle-based signal is also found. Further, the bit error rate (BER) of the proposed detection schemes is calculated using the analytical signal and validated using the particle-based signal. Simulation results show a good agreement between the BER obtained using the analytical signal and the particle-based signal.

Transmission and detection techniques for Internet of Bio-Nano Things applications with static and mobile molecular communication: A survey

Recent studies have shown that designing communication systems at nanoscale and microscale for the Internet of Bio-Nano Things (IoBNT) applications is possible using Molecular Communication (MC), where two or multiple nodes communicate with each other by transmitting chemical molecules. The basic steps involved in MC are the transmission of molecules, propagation of molecules in the medium, and reception of the molecules at the receiver. Various transmission schemes, channel models, and detection techniques have been proposed for MC in recent years. This paper, therefore, presents an exhaustive review of the existing literature on detection techniques along with their transmission schemes under various MC setups. More specifically, for each setup, this survey includes the transmission and detection techniques under four different environments to support various IoBNT applications: (i) static transmitter and receiver in a pure-diffusive channel, (ii) static transmitter and receiver in a flow-induced diffusive channel, (iii) mobile transmitter and receiver in a pure-diffusive channel, (iv) mobile transmitter and receiver in a flow-induced diffusive channel. Also, performances and complexities of various detection schemes have been compared. Further, several challenges in detection and their possible solutions have been discussed under both static and mobile scenarios. Furthermore, some experimental works in MC are presented to show realistic transmission and detection procedures available in practice. Finally, future research directions and challenges in the practical design of the transmitter and receiver are described to realize MC for IoBNT health applications.

Performance Evaluation of Mobile Molecular Communication System Using Neural Network Detector

This letter proposes a neural network (NN) detector for mobile molecular communication (MMC). The NN uses Broyden–Fletcher–Goldfarb–Shanno (BFGS), and Levenberg-Marquardt (LM) algorithms for optimization. In the proposed work, the received signal is filtered and three different techniques for supervised training and detection are used. The three different techniques are (a) the filtered signal, (b) slope values of the filtered signal, and (c) concentration difference values of the filtered signal within a bit interval. The trained NN is used for detecting the unknown bits for time-varying parameters such as the distance between transmitter (Tx) and receiver (Rx), noise, and the number of released molecules by the Tx. Bit error rate (BER) with the signal-to-noise ratio (SNR) is shown for different parameters such as coherence time of the channel, diffusion coefficient of the Tx, and the initial distance between the Tx and the Rx. Simulation results show that the BFGS algorithm trains the NN faster compared to the LM algorithm and the trained NN can perform well in a time-varying MMC environment.

Clock Synchronization for Mobile Molecular Communication Systems.

Molecular communication (MC) is a promising paradigm, which conveys messages at the nano- or micro- scale for information exchange by using molecules or particles as signal carriers. Clock synchronization between transmitters and receivers in MC systems plays an important role in information exchange and nanodevices' collaboration. The current research about the synchronization mainly focuses on fixed MC systems. However, the movements of transmitters and receivers commonly exist in MC systems. In this paper, two clock synchronization schemes, the least square method and the peak time method, are proposed to estimate the clock offset between a mobile transmitter and a mobile receiver in mobile MC systems. The synthesis time of information molecules is also taken into consideration in the proposed schemes, and by using different types of molecules, the influence of the synthesis time of molecules can be solved. The effects of the movement of receiver on the received signal are discussed. The performance of the proposed schemes is evaluated by simulations and discussed.

Power Control for ISI Mitigation in Mobile Molecular Communication

In mobile molecular communication (MC), inter-symbol interference (ISI) can be mitigated by power control, requiring accurate estimates of the distance from transmitter to receiver. We present two power control strategies based on binary concentration shift keying (BCSK), namely BCSK with power control based on distance (BCSK-d), and BCSK with power control jointly considering distance and residual molecules in the channel (BCSK-d-RM). Performance of BCSK-d and BCSK-d-RM are analyzed in terms of the bit error rate (BER), the average energy consumption per bit, and the optimal detection threshold. Simulation results show that BCSK-d-RM and BCSK-d outperform BCSK in BER with the varying distance and the number of transmitted molecules. As BCSK-d-RM has higher performance, while BCSK-d has lower complexity, these schemes present a useful design tradeoff for mobile MC.

DMole: A Novel Transreceiver for Mobile Molecular Communication Using Robust Differential Detection Techniques.

This paper proposes two differential detection techniques for signal detection in mobile molecular communication (MMC) for targeted drug delivery (TDD) application. In MMC, a nano-transmitter and a nano-receiver are considered to be in Brownian motion in an extracellular fluid medium. Transmitter uses calcium molecules to communicate with the receiver. Detection is performed using concentration difference based detector (CDD) at the receiver which calculates the maximum absolute concentration difference of the received signal within the same bit interval to detect the bit. This improves the bit error rate (BER) performance in MMC. The performance is further enhanced using manchester coded transmission with differential detection (MCD). In MCD, Bit-1 is coded by the symbol [1 0] and Bit-0 is coded by the symbol [0 1] and the difference between peaks of signals received in consecutive bit duration is taken to detect the bit. Simulation results prove that the MCD technique is 3 dB less sensitive to inter symbol interference (ISI) than the CDD technique. The detection threshold is selected using maximum a posteriori probability (MAP) rule. The performance of these detectors is compared with other existing detection techniques. Results reveal that BER performance of the CDD and MCD better by at least 3 dB and 6 dB, respectively. The proposed CDD and MCD techniques perform better in different bit-sequence length, various initial distance and different bit duration than other existing techniques.

Performance Analysis of D-MoSK Modulation in Mobile Diffusive-Drift Molecular Communications

Molecular communication (MC), in which molecules serve as the carrier for data transmission, plays an essential role in nanonetworks. In this article, a mobile diffusive-drift MC model is investigated, which consists of a mobile transmit nanomachine (TN) and a mobile receive nanomachine (RN). The depleted molecule shift keying (D-MoSK) modulation is utilized in this model to perform end-to-end communication. To explore the performance of D-MoSK, we derive the closed-form expressions of symbol error rate (SER) as well as the channel capacity, and then we give out the numerical results. It is observed from the numerical results that, if compared with the molecule shift keying modulation, the D-MoSK modulation can exhibit better performances in terms of SER, channel capacity, and complexity under the employed model. Also, the impacts of several crucial parameters on the performance are evaluated and discussed comprehensively. The obtained results are expected to provide guidance significance for the design of a practical mobile diffusive-drift MC system.

Initial Distance Estimation and Signal Detection for Diffusive Mobile Molecular Communication.

Mobile molecular communication (MC) attracts much attention in recent years where mobile nanomachines exchange information using molecules. In this paper, we consider a diffusion-based mobile MC system consisting of a pair of diffusive nanomachines. Due to the Brownian motion of nanomachines, the communication distance between the transmitter and the receiver is dynamic. Thus, the channel impulse response (CIR) is a stochastic process. The stochastic CIR brings the difficulty in the detection process. Contrast to the common static MC characterized by the deterministic CIR, in a mobile MC system, the receiver needs to estimate the dynamic distance for CIR reconstruction and detection threshold setting at each bit interval, which achieve high computational complexity. To tackle these difficulties, a new detection technique for mobile MC is proposed in this paper. It is unnecessary to estimate the dynamic communication distance at each bit interval. Instead, the receiver estimates the initial distance between it and the transmitter. The estimated initial distance can be used to reconstruct the statistical characteristics of CIR, setting detection threshold for all the bit intervals in advance. To achieve this goal, a novel two-step scheme based on maximum likelihood (ML) is proposed to estimate the initial distance. In the first step, the transmitter releases some molecules as a pilot signal before the information bits transmission. Then the receiver estimates releasing distance by observations of received signal. In the second step, the estimated value obtained in the previous step is used to estimate the initial distance by ML estimation. The performances of proposed two-step scheme and the detection technique are evaluated via particle-based simulation of the Brownian motion.