Research On Diversity Processing And Detection For Molecular Signals

As an emerging technology in the field of communication at the nanoscale,molecular communication takes messenger molecules as the carrier to complete information transmission through the fluid medium channels in the biological systems,and plays an important role in biomedical communication scenarios requiring microscale and low energy consumption.In the existing research on the signal detection of molecular communication,the traditional coherent detection scheme usually adopts complex channel estimation and matrix calculation to pursue better detection performance,while the traditional non-coherent detection scheme has a slight lack of detection performance in order to meet the requirements of low complexity.This thesis focuses on the biochemical reaction mechanism in molecular communication system,utilizes the theory of diversity processing,designs a non-coherent signal detection scheme based on local feature extraction,and implements the combination decision strategy through information fusion.Simulation analysis shows that the non-coherent detection scheme and decision strategy proposed in this thesis can reduce the bit error rate(BER)at a low complexity,so as to achieve the reliable transmission of molecular signals..The main research contents of this thesis are as follows:1)To deal with the biochemical reaction in biological channel,a system model of single-input multiple-output(SIMO)is formulated based on the idea of diversity reception.To be specific,the transmitter sends single messenger molecules,and the receiver uses the dynamical co-variation of messenger,reactant and product molecules in the biochemical reaction process,to recognize the multiple molecules synchronously by specific receptors,so as to detect the concentration of multiple molecules carrying the same information.2)On the basis of the synchronous reception of multiple molecules,a non-coherent detection scheme based on signal feature extraction is proposed by using the peak concentration and local convexity of molecular signals.In this scheme,the expressions of local feature extraction are constructed and the reasonable threshold is set to make decisions on the information bits in different molecular channels.The simulation results show that the detection performance of our proposed non-coherent detection scheme in this thesis is better than the typical non-coherent detection scheme based on concentration difference.3)Based on the non-coherent detection of multiple messengers,a combination decision algorithm based on information fusion is proposed.The algorithm adopts the maj ority rule and the equal-gain combining mode,to release the potential diversity gain of the communication system and improve the BER performance of the molecular communication.Theoretical analysis and simulation results show that the proposed combination decision algorithm avoids the complex matrix calculation and channel estimation,and obtains the detection performance better than the classical coherent algorithm,which has value of application in the field of biomedical.