High Resolution Direction Of Arrival And Range Estimation In Multipath Environment Of Millimeter Wave Radar

As a common target detection tool,mil imeter wave radar has the advantages of strong anti-interference ability,no fear of rain and snow,long detection distance,high detection accuracy,low cost and so on,and has a good application prospect in the civil field.At present,companies in various fields of security and automobile companies have increased investment in research and development of millimeter wave radar.However,when facing the real environment,mil imeter wave radar still faces many challenges,such as the interference caused by multi-path false targets in the multi-path environment,the detection accuracy compared with laser radar still has some shortcomings and so on.In multipath environment,the signal may produce correlation or even coherence,and some high-resolution algorithms based on subspace will fail.Because the working environment of radar is complex and multi-path propagation is common,it is necessary to study how to accurately estimate the true direction and distance of target in multi-path environment.Based on the frequency modulation continuous wave(FMCW)commonly used in millimeter wave radar,this paper studies the following contents:1.This paper studies the principle of ranging and angle measurement when FMCW adopts sawtooth wave modulation waveform,as well as related concepts,such as narrowband signal model and uniform linear array.2.The common DOA estimation algorithms,such as MUSIC algorithm,Min-Norm MUSIC algorithm and ESPRIT algorithm,are studied,and their application in beamspace is also studied.3.This paper studies the signal coherence model in multipath environment,studies Toeplitz and Forward-Backward Smoothing algorithm,analyzes the principle of these two algorithms,improves the Forward-Backward Smoothing algorithm,and proposes a new smoothing algorithm with better performance compared with Forward-Backward Smoothing algorithms.The beamspace,DOA estimation and the new smoothing algorithm are used together,which can not only reduce the computational complexity of the algorithm,but also effectively solve signal coherence.4.This paper studies how to use MUSIC algorithm to measure distance on the basis of FMCW,which can bring better range resolution than traditional DFT.The data received by the array is adjusted appropriately,and a 2-D TDOA joint estimation algorithm is proposed,and the smoothing algorithm proposed in this paper is also extended to 2-D case.When the smoothing algorithm is extended to two-dimensional application,not only the signal coherence can be removed,but also more time average data can be obtained,which can reduce the amount of data that needs to be sampled for TDOA estimation.The beamspace is also combined to reduce the computational complexity.Finally,the related parameters and signal processing flow of mil imeter radar platform are introduced,and the feasibility of the proposed algorithm is verified by real data.