Research On Key Technologies Of Array Single-photon Communication For Dynamic Light Intensity

With the rapid growth of people's demand for information transmission services and the progress of solid-state lighting technology,visible light communication as a new wireless communication technology has attracted more and more attention.Single photon detection devices with high sensitivity further expand the distance of visible light communication,and make breakthroughs in the research of various complex channel conditions.However,the traditional single photon detection devices have some defects,such as low detection efficiency,small dynamic range and dead time effect,which are difficult to meet the needs of the development of visible light communication system.In order to solve the above problems,arrayed single photon detector becomes the focus of the next stage.This paper studies the multi-pixel photon counter based on the array structure,analyzes the photon counting models under different conditions,and proposes the corresponding detection algorithm.Finally,the visible light communication experimental system is designed and implemented.The main research contents are as follows1.Aiming at the problems of small detection dynamic range and serious dead time effect of single point structure single photon detector,the response model of multi-pixel photon counter is studied,and the maximum likelihood detection algorithm in weak light environment is proposed.Firstly,the working principle and structural characteristics of the array photonic receiver are introduced.Then,several main noise factors affecting the performance of the receiver are analyzed.Based on this design,a large-scale photon level Monte Carlo numerical simulation based on the array receiver is completed,and the photon count distribution model is obtained.Then,the visible light communication system model under ideal weak light condition is established,and the simulation results are derived The maximum likelihood detection algorithm in the linear response region and the BER expression are given.Finally,the BER performance of the system is simulated.The results show that the performance of the proposed detection algorithm is better than the existing detection algorithms in the linear region.2.For the applicability of array single photon detector in light intensity changing scene,the distribution model of receiver under different illumination conditions is studied,and the nonlinear likelihood detection algorithm is proposed.Multi pixel photon counter has the characteristics of high dynamic detection range,and its response characteristics are different in the scene of light intensity change.Firstly,the visible light communication link model based on pulse amplitude modulation is established,and the design of multi wick light source and the signal processing model of receiver are introduced.Then,the relationship between the number of photons in the process of transmission is analyzed,and the response curve is divided into three working areas according to different incident light intensity,and the photon counting model in different working areas is studied.Finally,according to the actual photon response relationship,a nonlinear likelihood detection algorithm is proposed.Simulation and experimental results show that the nonlinear likelihood detection algorithm takes dead time effect and saturation effect into account,and performs better than the detection algorithm based on ideal model.3.Design and implement the indoor visible light communication experimental system based on array single photon detector,and verify the accuracy of the distribution model and detection algorithm.Due to the performance limitations of existing single photon detection devices,firstly,a visible light communication system in darkroom environment is built by using multi-pixel photon counter as the receiving end,and the signal synchronization mode suitable for the system is designed and implemented in the development board.Then the eye diagram of the system is recorded to verify the correctness of the theoretical model under the condition of dynamic light intensity.Finally,the simulation results are given.The algorithm is applied to the system,and the effectiveness of the proposed algorithm is verified by comparing the experimental data.