| Smart home,intelligent security and other technologies have gradually penetrated into people’s daily life in the era of artificial intelligence nowadays.Non-line-of-sight target detection technology has very important value in such applications,so it has become a research hotspot at home and abroad.With the booming development of wireless communication technology,it is of great significance to design a low-cost and small-size target detection system in indoor non-line-of-sight scene.Researchers have paid extensive attention to the advantages of low-cost indoor Wi Fi signal detection with the deployment of low-cost Wi Fi signal.The existing indoor non-line-of-sight target detection technology based on Wi Fi channel state information has great limitations in practical application because of its poor interference suppression effect and single signal parameter extraction.To solve the above problems,this thesis studies the passive dynamic target detection algorithm in indoor non-line-of-sight scene based on Wi Fi channel state information,focuses on the principle of interference signal suppression in indoor non-line-of-sight scene,proposes a low complexity multi-dimensional signal parameter estimation algorithm and target detection scheme,and its validity is verified by tests.The main research contents of this thesis are as follows:Firstly,the interference signal suppression algorithm is studied.The error source analysis,interference signal analysis and signal model construction of the received signal under the commercial Wi Fi platform are carried out.Then,the phase error and interference signal in the monitoring channel are suppressed by constructing the reference channel,and the interference suppression algorithm is realized,the channel state information of the target signal after final interference suppression is obtained.Secondly,the low complexity multi-dimensional signal parameter estimation algorithm is studied.By using the channel state information obtained under multi antenna and multi carrier after interference signal suppression,a two-dimensional multi packet matrix beam algorithm is proposed for joint estimation of Angle of Arrival and Time of Fight.While reducing the complexity of the traditional matrix beam algorithm,through multi packet accumulation,the accuracy of parameter estimation is guaranteed in the environment of low signal-to-noise ratio.Finally,the non-line-of-sight dynamic target detection algorithm is studied.Based on the multi-dimensional parameters of the signal,a signal feature extraction algorithm is designed to extract the characteristic parameters of the signal,and the machine learning algorithm is used to classify the characteristic parameters to achieve indoor non-line-of-sight passive dynamic target detection.Our system built a multi-antenna commercial Wi Fi test and verification platform,and tested in multiple scenarios.The detection accuracy reached 98.52%,94.56% and 91.27% respectively in the non-lineof-sight environment with glass wall,brick wall and concrete wall. |
