Discrete Grid based Detection Strategies for Distributed MIMO Radars

This paper considers the detection problem for distributed multiple-input multiple-output (DMIMO) radars under the “defocused transmit-defocused receive” (DTDR-DMIMO) operating mode. In particular, the range cells of different transmit-receive channels are not in superposition, but intersecting with each other, so the test cell, which is the cell under test (CUT) corresponding to each test, is hard to determine for jointly processing of sampling data from all channels. To address this problem, we first propose shape fitting method (SFM) to divide the surveillance area into a number of closely spaced and small size discrete grids, and determine the authentic test cells by condensing the grids, which share the same data, into one test cell. Since the number of test cells is enormous, the cost for SFM is huge. To reduce the implementation expenses, we furthermore propose homogeneously covering method (HCM) to set a smaller number of identically rectangle shaped grid cells in the surveillance area, and select the best fitted data for one grid cell by matching the range cells of every channel with this grid cell. In addition, two likelihood ratio test (LRT) detectors with constant false alarm rate (CFAR) for SFM and HCM are derived, respectively. Finally, simulation experiments have shown that both SFM and HCM can efficiently solve this problem.

I. Introduction

Multiple-input multiple-output (MIMO) radars has received great attentions in both the academic and the industrial field [1], [2]. There are mainly two important categories of MIMO radars according to the antenna elements relative to the transmitted wavelength. In the first category, different transmit and receive antenna elements are sufficiently close to each other. Parameter identifiability and detection performance can be significantly improved with waveform diversity in this system [3]–[5]. In the second category, distributed MIMO (DMIMO) radars is well-known with widely separated transmit/receive antenna elements. We can improve detection and localization performances, and decrease the radar cross section (RCS) fluctuation effect with DMIMO radars by utilizing space diversity [6]–[9]. The DMIMO radars under the “defocused transmit-defocused receive” (DTDR-DMIMO) operating mode, in which each transmitter forms a completely defocused beam to illuminate the whole surveillance area and each receiver adopts a defocused beam, is a common one with little time consumption [10].