Research On Information Transmission Techniques For Multi-scale Molecular Communication Systems

Living organisms in nature,from the micro-scale cells to the macro-scale animals and plants,use specific types of molecules as carriers for information transmission.Molecular communication(MC)is defined as the mechanism that uses characteristics of the information molecules,such as concentration,type,and release time,to carry information,whose concept was first proposed in 2005.Compared with other communication technologies,the research history of molecular communication is relatively short.MC has multi-scale application scenarios,mainly divided into two types,i.e.,micro-scale and macro-scale.In the micro-scale,nanomachines can build the connection and networking in vivo to achieve intelligent medical services such as targeted drug delivery via MC.The research problem for micro-scale MC is eliminating inter-symbol interference(ISI)and non-stationary noise,whose variance correlates to the signal strength.Moreover,the computational complexity of the emission and detection algorithms should be taken into account.Alternatively,the macroscale MC is used for pollution detection or the alternative communication paradigm when traditional communication schemes are limited.Its current task is mainly to realize the information transmission of the prototype.Specifically,the main contributions of this thesis are summarized as follows:1)In addition to the traditional time-domain analysis,the micro-scale molecular communication system is studied via the frequency perspective for the first time.The bandwidth of the channel impulse response(CIR)is defined based on frequency domain analysis,and the sampling frequency is also proposed.Besides,inspired by the molecular release mechanism in the macro-scale MC prototype,a new three-stage micro-scale channel model is presented.2)Concerning the single-input single-output based MC(SISO-MC)system,a signal detection scheme that uses frequency domain equalization(FDE)techniques is proposed to combat the severe influence of ISI.The FDE achieves a lower complexity relative to time-domain equalization and maximum likelihood sequence detection to combat the severe problem of ISI,achieving ideal detection performance.3)The multiple-input multiple-output based molecular communication(MIMO-MC)system has the problem of existing both the ISI and the inter-link interference(ILI).Spatial modulation(SM)technique is proposed for MC to overcome ILI and achieve a lower complexity signal detection algorithm for the micro-scale MC receiver,where the corresponding detection performance is also derived.4)The signal detection and design issues for the MC prototype are considered.According to the characteristics of the air channel prototype signal,a detection algorithm based on the strength of the rising edge is proposed for the system.Besides,the SISO-MC and MIMO-MC prototypes in the liquid channel are proposed.