| MIMO radar has been proved to perform better than the traditional phased array radar in target imaging, target parameters estimation and target tracking. However the problem of phase mismatch deteriorates the detection performance greatly. There are some problems need to be solved in the existing synchronization algorithms for phase synchronization: firstly, they only achieve the phase synchronization between the transmitting antennas while the channel phase mismatch between the transmitting antennas and the target, which may be more important; secondly, the synchronized overhead of the existing algorithms increases rapidly as the number of transmitting antennas increases, which limits its application greatly; thirdly, up to my best knowledge, there is no public literatures which deal with the phase mismatch problem in a moving target scenario.In order to solve these problems, this thesis proposed a new kind, i.e., the interactive MIMO radar which consists of two antenna arrays. Both of them are capable of transmitting and receiving. In addition, we proposed a phase synchronization algorithm for the MIMO radar system. For the new algorithm, the two arrays are operating by a time-slotted way, which means, the first array transmits the detection signals in odd timeslot while the second array transmits in even timeslot. The proposed phase synchronization algorithm needs only one extra timeslot to achieve phase synchronization at the target no matter how many transmitters are. Therefore, the proposed radar system improves the performance obviously but with low overhead compared with the existing algorithms.The proposed phase synchronization algorithm has been further extended to a moving-target scenario. We considered two scenarios, i.e., the target moves along a circular and straight line. We took the signal processing of the first array as an example to describe the details of implementation scheme. For a defined loop which contains two timeslots, the first array estimates their frequencies and phases of the received signals and predicts the trajectory of moving target firstly. Then, the prediction results are utilized to compensate the phase mismatch of moving target in the subsequent timeslots. For the straight line trajectory, two loops are required to obtain the moving state and three loops for the circular trajectory. Therefore, after at least 4 and 6 time slots, an relatively ideal phase synchronization will be achieved in the straight line and circular trajectory respectively. Through both the theoretical probability of detection and the simulation results, the efficiency of the proposed phase synchronization algorithm in the proposed MIMO radar has been verified in both the static target and moving target scenarios. |
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