Research On Low-complexity Direction Finding Method Of MIMO Radar System

Making reference to the MIMO (Multiple-Input Multiple-Output) thought in mobile communication field, MIMO radar draws lots of attention once proposed. MIMO radar uses multiple transmit array elements to send mutually orthogonal signals and multiple receive array elements to receive the back waves. Compared to traditional phased array radar, MIMO radar owns higher degree of freedom, better parameter estimation ability and outstanding anti-interference and stealth target detection performance. Therefore, MIMO radar has extensive application prospects. Direction finding based on MIMO radar is a research focus currently. However, pertinent algorithms can’t meet the realtime requirement because of the accordingly rising computational complexity caused by the complicated MIMO radar signal model and massive data volume. Discussion and research are done based on monostatic MIMO radar and bistatic MIMO radar signal model respectively to reduce the computational complexity of direction finding method of MIMO radar. Relevant computationally efficient direction finding methods of MIMO radar are proposed in this paper.Firstly, the current situation and basic theories of direction finding of MIMO radar are studied. The array model and direction finding mathematical model of MIMO radar are presented. Several popular direction finding algorithms of MIMO radar are studied then with their principles intruded and performance analyzed thoroughly.Secondly, direction finding methods of monostatic MIMO radar are studied to improve computational efficiency, data efficiency and decoherent performance. By using the particular monostatic MIMO radar signal model and non-circular character, a DOA estimation method using non-circular signals for monostatic MIMO radar is proposed in this paper. Further to detect coherent targets, a coherent DOA estimation method using non-circular signals for monostatic MIMO radar is proposed by making reference to the spatial smoothing technology and the method correctly detects coherent targets.Finally, joint DOA (Direction of Arrival) and DOD (Direction of Departure) estimation methods of bistatic MIMO radar are studied to improve computational efficiency, data efficiency and decoherent performance. To reduce computational complexity and improve decoherent power of current algorithm, a unitary Root-MUSIC algorithm is proposed in this paper. A real-valued operation is used to transform the conjugate computation to real-valued computation and reduce computational complexity efficiently. Without using the spatial smoothing technology, the proposed method detects coherent targets without debasing array effective aperture.