Simulation Algorithms for Absorbing Receivers in Diffusion-Based Molecular Communication Systems: An A Priori Approach

Molecular Communication (MC) has emerged as a cutting edge technique for exchanging and conveying information among nano-devices in very small dimensions or specific environments, such as water, tunnels, and human bodies. It is worthwhile noting that existing simulation algorithms for diffusion-based MC systems incur high computational complexity when simulating the absorption of molecules at receiver(s). Specifically, the existing algorithms require a very small simulation time step length to accurately model the absorption, leading to a long simulation run time. Against this background, this thesis aims to reduce the computational complexity for the simulation of absorption at receiver(s) in a diffusion-based MC system. In Chapter 3, the system models of the investigated problem are introduced. To be specific, the MC system with both a single absorbing receiver and that with multiple absorbing receivers are considered. The analytical reaction probabilities of molecules with absorbing receiver(s) are discussed. Furthermore, the intra-step absorption probabilities used in algorithms for simulating absorbing receiver(s) are presented. In Chapter 4, existing simulation algorithms for absorbing receiver(s) in diffusion-based MC systems are carefully examined and the similarities and differences among algorithms are discussed. To quickly predict the simulation accuracy of an existing algorithm, the refined Monte Carlo (RMC) algorithm, a new expression is proposed as a function of the simulation time step length and system parameters. After discovering that the RMC algorithm enables accurate simulation for a relatively small simulation time step length only, a novel a priori Monte Carlo (APMC) algorithm is proposed to accurately simulate the molecules absorbed at spherical absorbing receiver(s) with low computational complexity for relatively large simulation time step lengths. Moreover, by analyzing the computational complexity of the APMC algorithm and the RMC algorithm, a likelihood threshold is proposed to reduce the computational complexity for both algorithms. In Chapter 5, numerical results are shown to evaluate the aforementioned simulation algorithms. It is obvious from the results that using the prediction expression for the RMC algorithm, we can characterize the accuracy of the simulation results of the RMC algorithm without running it, which facilitates the selection of simulation time step length for a given system. It is also demonstrated that the APMC algorithm effectively overcomes the shortcoming of the existing algorithms. It is further shown that after applying an appropriate likelihood threshold to the APMC algorithm and the RMC algorithm, the computational complexity is significantly saved while only an extremely small loss in accuracy is caused

A Novel A Priori Simulation Algorithm for Absorbing Receivers in Diffusion-Based Molecular Communication Systems

A novel a priori Monte Carlo (APMC) algorithm is proposed to accurately simulate the molecules absorbed at spherical receiver(s) with low computational complexity in diffusion-based molecular communication (MC) systems. It is demonstrated that the APMC algorithm achieves high simulation efficiency since by using this algorithm, the fraction of molecules absorbed for a relatively large time step length precisely matches the analytical result. Therefore, the APMC algorithm overcomes the shortcoming of the existing refined Monte Carlo (RMC) algorithm which enables accurate simulation for a relatively small time step length only. Moreover, for the RMC algorithm, an expression is proposed to quickly predict the simulation accuracy as a function of the time step length and system parameters, which facilitates the choice of simulation time step for a given system. Furthermore, a rejection threshold is proposed for both the RMC and APMC algorithms to significantly save computational complexity while causing an extremely small loss in accuracy.Comment: 11 pages, 14 figures, submitted to IEEE Transactions on NanoBioscience. arXiv admin note: text overlap with arXiv:1803.0463

Modeling and Simulation of Molecular Communication Systems with a Reversible Adsorption Receiver

In this paper, we present an analytical model for the diffusive molecular communication (MC) system with a reversible adsorption receiver in a fluid environment. The widely used concentration shift keying (CSK) is considered for modulation. The time-varying spatial distribution of the information molecules under the reversible adsorption and desorption reaction at the surface of a receiver is analytically characterized. Based on the spatial distribution, we derive the net number of newly-adsorbed information molecules expected in any time duration. We further derive the number of newly-adsorbed molecules expected at the steady state to demonstrate the equilibrium concentration. Given the number of newly-adsorbed information molecules, the bit error probability of the proposed MC system is analytically approximated. Importantly, we present a simulation framework for the proposed model that accounts for the diffusion and reversible reaction. Simulation results show the accuracy of our derived expressions, and demonstrate the positive effect of the adsorption rate and the negative effect of the desorption rate on the error probability of reversible adsorption receiver with last transmit bit-1. Moreover, our analytical results simplify to the special cases of a full adsorption receiver and a partial adsorption receiver, both of which do not include desorption.Comment: 14 pages, 8 figures, 1 algorithm, submitte

Detection Algorithms for Molecular MIMO

In this paper, we propose a novel design for molecular communication in which both the transmitter and the receiver have, in a 3-dimensional environment, multiple bulges (in RF communication this corresponds to antenna). The proposed system consists of a fluid medium, information molecules, a transmitter, and a receiver. We simulate the system with a one-shot signal to obtain the channel's finite impulse response. We then incorporate this result within our mathematical analysis to determine interference. Molecular communication has a great need for low complexity, hence, the receiver may have incomplete information regarding the system and the channel state. Thus, for the cases of limited information set at the receiver, we propose three detection algorithms, namely adaptive thresholding, practical zero forcing, and Genie-aided zero forcing.Comment: 6 pages, 6 figures, 2015 IEEE ICC accepte