Xizeng Dai

Optimizations of Multisite Radar System with MIMO Radars for Target Detection

This paper proposes a novel multisite radar system (MSRS) with multiple-input and multiple-output (MIMO) radars, i.e., MIMO-MSRS system, to improve the detection performance of fluctuating targets. The proposed MIMO-MSRS system increases the local signal-to-noise ratio (SNR) by using digital beamforming (DBF) among all transmitting and receiving channels in a single site. Then it smoothes the targets fluctuation via spatial diversity among the DBF outputs of different sites. For the MIMO-MSRS system, we derive the likelihood ratio test (LRT) detector at first based on the proposed signal model and spatial diversity conditions. Furthermore, with the derived statistics of the LRT detector in the fixed noise background, three optimization problems are discussed on the MIMO-MSRS system configurations, i.e., the numbers of sites and collocated channels in different sites. The first problem is to detect the lowest SNR target with a given probability of false alarm (PF), probability of detection (PD) and total system degrees of freedom (DOF). The second is to detect a target with the highest PD for a given PF, target SNR, and system DOF. The third is on the minimal system DOF to detect a target with a given PF, PD, and target SNR. For the uniform MIMO-MSRS system, both the standard optimal site number, i.e., the diversity DOF, and its closed-form approximation of the above three problems are obtained. Finally, some numerical results are also provided to demonstrate the effectiveness of the proposed MIMO-MSRS systems.

A new method of improving the weak target detection performance based on the MIMO radar

Based on the spatial diversity of the multiple input multiple output (MIMO) radar, a new method is presented to improve the detection performance of weak targets in clutter in this paper. First, the general spatial diversity condition is deduced. Accordingly, by selecting suitable MIMO radar spatial configuration, the target and clutter in a detection unit may be regarded as the non-fluctuating and the fluctuating components, respectively. Therefore, an effective method to exploit the spatial diversity to increase the signal-to-clutter-plus-noise ratio of the receiver is proposed. Compared to the conventional radar, it is shown that superior detection performance may be obtained with the proposed method, especially for the weak target in clutter. Finally, detailed numerical experiments are also provided to demonstrate the effectiveness of the proposed method

Low-sidelobe HRR profiling based on the FDLFM-MIMO radar

The frequency-division linear frequency modulation MIMO (FDLFM-MIMO) radar is proposed in this paper, which can synthesize high-resolution range profile (HRRP) for ISAR/SAR imaging via a group of narrow-band LFM signals without over-demands on system bandwidth and sampling rate. Unfortunately, it is depicted that the HRRP sidelobes of the FDLFM-MIMO radar may be too high. According to the cause of the sidelobes, a novel alternative transmission scheme and an extended matched filter are proposed, and a weighting window is also applied. Finally, the numerical experiments are given to show the effectiveness of the methods.

Using GA to design discrete frequency-coding waveform for orthogonal multistatic ISAR

In this paper, we discussed how to use the genetic algorithm(GA) to design discrete frequency-hopping waveforms for orthogonal multistatic ISAR (inverse synthetic aperture radar). Based on the novel and creative using of GA, the optimization problem is well solved and the design results have good performance in auto-correlation and cross-correlation. The obtained results in this paper can be implemented in real multistatic ISAR systems.

Optimal transmitting diversity degree-of-freedom for statistical MIMO radar

Statistical multiple-input multiple-output (MIMO) radar may improve the fluctuated target detection by utilizing the multiple separate transmitting and receiving elements. Nevertheless, the transmitting power of single element is reciprocal to the transmitting element number, and the ultimate detection performance of MIMO radar may be inversely deteriorated with the increase of the transmitting elements. In this letter, the optimal transmitting diversity DOF, i.e., the optimal separate transmitting elements, is defined based on the proposed likelihood ratio test (LRT) detectors. Furthermore, with the given false alarm probability and detection probability, the closed-form optimal DOF approximations are derived for the two sub-forms of statistical MIMO radar, i.e., distributed MIMO radar and multiple-input single-output (MISO) radar, respectively. It is shown that a small transmitting diversity DOF, as well as the small number of orthogonal transmitting waveforms, may be needed for optimizing the statistical MIMO radar spatial diversity performance. Finally, numerical experiments are also provided to demonstrate the effectiveness of the proposed methods.