Research On Molecular Communication Channels With Binding Reception

Molecular communication(MC)is a novel communication paradigm focusing on the research of nano-scale information exchange,where chemical or biological molecules are employed as information carriers.Compared to the conventional electromagnetic communication,MC is mainly applicable for transmitting signals within fluid media,e.g.,body fluids and chemical solutions.MC systems are bio-compatible,where the transceivers are nanodevices and require very little energy to generate or detect molecular signals.Thus,MC can be used for biomedical engineering applications,including drug delivery,targeting substances,and virus transmission analysis.The diversity of the potential applications leads to MC system models of multiple different types.Learning the method of biological cells receiving molecular signals,the MC systems based on ligand-binding reception mechanism are with high realizability and prevalent in the designs of nano-networks and the development of brain-machine interfaces in recent years.Hence,channel modeling and analysis for the MC systems using ligand-binding reception mechanism is one of the hot topics in theoretical research.Thus,this dissertation concentrates on the MC systems based on ligand-binding reception mechanism,for which the channel models and the information rates in different communication scenarios are investigated.The main work of this dissertation is as follows.(1)Channel modeling and characteristic analysis for the signal transduction channel(STC)were investigated.According to the Markovian nature of the ligand-binding process,a probability model of the STC is developed.When the channel inputs are constrained to IID random variables,the maximum information rate was proved to be achieved by a discrete input distribution.The sufficient and necessary conditions of the IID maximum-rateachieving distribution were also investigated,based on which a numerical algorithm was developed to compute the maximum information rate and its achieving input distribution.The numerical results verified the discreteness of the IID maximum-rate-achieving distribution.(2)Channel modeling and achievable rate analysis for the diffusion binding channel with finite ligand receptors were presented.For a binding receiver with finite receptors,a new boundary condition was proposed to model the reversible binding reaction.By taking the diffusion process of information molecules into account,a two-step method was proposed to approximate the binding receiver to an ideal one.Based on the proposed approximation method,an iterative algorithm was developed to model the diffusion-binding channel.Then,by constraining the channel inputs to IID random variables,a lower and an upper bounds on the diffusion-binding channel were derived.At last,the numerical results verified the effectiveness of the iterative algorithm.(3)Channel modeling and achievable rate analysis for the 2 × 2 MIMO diffusion-binding channel were explored.Firstly,an analytical channel model was proposed for the 2×2 MIMO MC system equipped with two spherical binding units,where the mutual impact between the binding units was taken into consideration.For a target binding unit,its impacted area was then investigated by comparing the channel model to the one obtained in the corresponding SISO scenario.Based on the normalized root-mean-square error criterion,the impacted area was numerically analyzed.Besides,the achievable rate of the MIMO system was analyzed,for which a lower and an upper bounds were developed.The numerical results verified the effectiveness of the proposed channel model,and showed the remarkable improvement of the MIMO technique in data rate.