Performance Of Molecular Communication Research Articles

A Pulse Position-Based Spatio-Temporal Coded Modulation for Molecular MIMO Systems

Multiple-input multiple-output (MIMO) technology is helpful with improving the communication throughput and performance of molecular communication (MC) systems. Though index modulation (IM) approaches aid to alleviate intersymbol interference (ISI) and interlink interference (ILI) issues in molecular MIMO systems by encoding the information in the antenna index, ISI and ILI problems still exist in such environments. Coded modulation strategies show promising results in terms of system error performance due to their better ISI and ILI combating capability. In this letter, a novel coded modulation scheme is proposed where the pulse position constellation is incorporated with the coded antenna indices. The proposed scheme is shown to yield an improved error performance owing to its better ILI mitigating strength.

Molecular Communications Enhanced by Time-Varying Electric Field.

In this work, we propose applying a time-varying electric field to a time-slotted molecular communication system with ionized message particles to combat inter-symbol interference (ISI) and enhance the transmission performance. Firstly, the solution to the Nernst-Planck equation, which describes the motion of ions under the electric field, is derived. With the derived solution, the bit error probability (BEP) and the receiver operating characteristic (ROC) curve are analyzed. Then, the time-varying electric field is optimized by the proposed algorithms to respectively minimize the error probability (MinEP), maximize the signal-to-interference ratio (MaxSIR), and maximize the sensing probability (MaxSP). For solving the MinEP and MaxSIR problems, algorithms based on the approximate gradient descent method are proposed. In addition, an efficient algorithm is proposed for solving the MaxSP problem. The proposed MinEP and MaxSIR schemes are shown to effectively mitigate ISI, and the proposed MaxSP scheme delivers the near-optimal performance with low complexity, demonstrating that the performance of molecular communications can be significantly enhanced by applying the time-varying electric field.

Effects of Framing Errors on the Performance of Molecular Communications With Memory

In conventional digital communication systems, synchronous transmission is achieved by embedding the clocking information into the data signal. However, the implementation of this technique in molecular communication systems, which rely on the diffusion of molecules as information carriers, becomes very complex due to the randomness of the diffusion process. Hence, in this paper we consider the molecular communication between two nanoscale devices with no exchange of any clock signal. To initiate the communication, the transmitter sends a special molecular symbol called beacon in order to trigger the detection process in the receiver. Therefore, this beacon symbol is equivalent to the start bit used for framing in asynchronous serial communication systems. We assume that both transmitter and receiver clocks are perfect, but not synchronized. Accordingly, the analysis focuses on the effects of framing errors on the performance of the molecular channel, measured via the symbol error probability. These errors are inherent to the random nature of the beacon arrival instant, which tends to degrade the alignment between the transmitter and receiver frames. We also assume a molecular channel with any level of inter-symbol interference and the use of different types of molecules to encode information symbols. We validate the derived SEP expression by means of extensive simulation experiments, and finally we develop a design scheme for the beacon symbol that satisfactorily mitigates the effects of framing errors.

Reliability Analysis of Molecular Communication Based on Drift Diffusion in Different Topologies

Molecular communication is a novel nanoscale communication method. It can use ions, biochemical molecules or other information carriers to transmit information. However, due to molecules are easily accumulated in the channel to produce strong internal symbol interference, the information transmission in the channel is vulnerable to a low reliability. Therefore, reliability has become an important research issue in the field of molecular communication. At present, the existing reliability model of molecular communication does not take into account the drift velocity of the medium. Nevertheless, in some scenarios, it is often necessary to consider the effect of the drift velocity of the medium on the reliability of molecular communication. In this paper, we introduce the drift velocity of the medium and propose a reliability model of molecular communication based on drift diffusion (MCD2) in different topologies. Furthermore, in the case of transmission failure, a retransmission mechanism is used to ensure reliable transmission of information. Finally, we also compare the reliability performance of molecular communication between reliability model of MCD2 and reliability model of molecular communication based on free diffusion. The simulation results indicate that the proposed reliability model is superior to the existing reliability model of molecular communication based on free diffusion in analyzing the reliability of MCD2.

On Flow-Induced Diffusive Mobile Molecular Communication: First Hitting Time and Performance Analysis

This paper investigates the problem of flow-induced diffusive molecular communication under various mobility conditions, such as: 1) both transmitter (TX) and receiver (RX) nanomachines are mobile; 2) TX is mobile and RX is fixed; and 3) TX is fixed and RX is mobile. In particular, a 1-D environment with a point TX and a fully absorbing point RX is considered. Closed-form expressions for the probability density function (PDF) of the first hitting time under the aforementioned mobile scenarios are derived, by characterizing the movement of the nanomachines and information molecules using Brownian motion with positive drift. The derived PDF expressions are validated through particle-based simulations. Based on these results, the performance of molecular communication with on-off keying (OOK) modulation in flow-induced diffusive channels is investigated. In particular, closed-form expressions for the probabilities of detection and false alarm with likelihood ratio test (LRT)-based decision rule, probability of error, and the achievable rate in the presence of inter-symbol interference, counting errors, and noise from the other sources are derived. Simulation results are presented to verify the theoretical results and to yield insights into the system performance for different mobility conditions.

Effect of Receptor Density and Size on Signal Reception in Molecular Communication via Diffusion With an Absorbing Receiver

The performance of molecular communication is significantly impacted by the reception process of the messenger molecules. The receptors' size and density, however, have yet to be investigated. In this letter, we analyze the effect of receptor density and size on the signal reception of an absorbing receiver with receptors. The results show that, when the total receptor area is the same, better hitting probability is achieved by using a higher number of relatively small receptors. In addition, deploying receptors, which cover a small percentage of the receiver surface, is able to create an effective communication channel that has a detectable signal level.