Clock Synchronization Algorithm For Molecular Communication System

Molecular communication is a short range communication technology which uses nanometric scale molecules as the information carriers.As one of the communication solutions between nano-level devices,the characteristics of biological compatibility make molecular communication have a wide application prospect,which has become one of the hot topics in the field of communication.With much advancement in the field of nanotechnol-ogy,bioengineering,and synthetic biology over the past decade,microscales and nanoscales devices are becoming a reality.Similar to traditional radio communications,it is necessary that two nanomachines need a synchronous clock for performing complex tasks.Three problems are solved in this paper.clock synchronization in mobile communication system,one symbol blind synchronization in molecular communication systems and distance estimation in molecular communication via diffusion.Based on probability theory and mathematical statistics,such as probability density function,maximum likelihood estimation,mean square error and newton Newton-Raphson Method,the clock synchronization technology in molecular communication system is studied.The main contributions are as follows.1.Clock synchronization is an essential issue for the collaboration of the nanodevices.How to synchronize the nanomachine in a mobile scenario is a challenge.We propose a method to estimate the clock offset in mobile molecular communication systems.We propose a method to estimate the clock offset base on MaximumLikelihood Estimation(MLE)in mobile molecular communication system.Finally,simulations by MATLAB are performed and the results show that the mean square error(MSE)of the estimated clock offsets can be reduced and converges after a number of rounds of message exchange,which manifests the effectiveness of the proposed solution.2.Clock Similar to other communication paradigms,molecular communication also requires clock synchronization between the transmitter and the receiver nanomachine in many applications.We present a blind clock synchronization mechanism.Without knowing the channel parameters of diffusion coefficient and transmitter-receiver distance,the receiver samples the molecular concentration temporally from one symbol transmission.These samples are used to estimate the propagation delay by least square method and further to achieve clock synchronization.Single-input multiple-output(SIMO)diversity design are proposed to sample the received concentration spatially to mitigate channel noise and therefore to improve the synchronization accuracy.The simulation results show that the proposed clock synchronization mechanism has a good performance.3.The distance between the nanomachines is an important parameter in the molecular communication system.It is useful parameters in the clock synchronization protocol,we propose multiple symbol protocol for estimating distance based on maximum likelihood estimation.The receiver nanomachine estimates the distance by sampling the concentration from multiple symbols.The inter-symbol interference(ISI)and additive noise are considered.The Newton-Raphson method is used to calculate the estimated distance.The performance of the proposed protocol is evaluated by simulation in MATLAB.The results show that the proposed scheme achieves good performance in the ISI scenario.