Array Design And DOA Estimation Of MIMO Radar Based On Sparse Nested Array

Multiple-input multiple-output(MIMO) radar is a new radar system developed in recent years. Compared with the traditional radar, it has many unique advantages, such as the breakthrough of the limit that the array element spacing can not be greater than the half wavelength, increasing the angle resolution, improving the system degree of freedom, the enhancement of the interference and the clutter suppression ability. Therefore, the MIMO radar has become a hot spot in the domestic and foreign research, and has become one of the main development directions of the next generation radar.Co-located MIMO radar is one of the MIMO radar main categories. Originally, the antennas array structure of Co-located MIMO radar is even, which has low resolution and high price. In order to improve the resolution and reduce the cost of antenna array, MIMO radar began to gradually adopt the sparse array. This paper is based on a new sparse array-- nested array,and it mainly studies on the array design and the direction of arrival(DOA) estimation of MIMO radar, which is based on the nested array. The Main contents are as follows:Describe the development of sparse array in array antenna, types and key technologies of MIMO radar. Introduce the basic model of MIMO radar, including the principle of virtual array, waveform design and signal model of co-located MIMO.Describe the basic concept and principle of sparse array, and discuss the two different sparse arrays-- the principle of minimum redundancy array and a new type sparse arrays named nested array. Carry out DOA estimation of the targets by using two level nested array, and make a conclusion that the forward backward spatial smoothing algorithm can not increase the degree of freedom of the system, which is analyzed in theory.Discover that the main interpolation algorithm of DOA estimation at present are unable to estimate the DOA of the targets when using optimally nested array, which is also analyzed in theory.Carry out the DOA estimation of two level nested array and minimum redundancy array by using forward spatial smoothing method. Make a conclusion that although the freedom of two level nested array is slightly smaller than the minimum redundant array, but it can solve the problem that the array design of minimum redundant array needs a large number of search, which can save a lot of time.Describe an array design and an improved DOA estimation of MIMO radar which are based on the nested array and are simulated. Simulation results show:(1) Compared with the conventional array design method of MIMO radar, nested array MIMO radar described in this paper can effectively increase the degree of freedom. And it can solve the problem of the underdetermined DOA estimation in the traditional MIMO radar.(2)The DOA estimation algorithm of the sparse array in this paper has high spatial resolution and it can effectively solve the problem of the existence of pseudo peaks in the results. Compared with other earlier proposed algorithms, this algorithm has better performance in terms of angle estimation.