Gain and phase uncertainties would destroy the invariance property of both the transmit array and the receive array in bistatic MIMO radar, so the computationally efficient ESPRIT algorithm cannot be applied directly. Proposed is a novel ESPRIT-like algorithm, which uses the instrumental sensors method (ISM), to estimate the direction of departures and direction of arrivals. The ESPRIT-like algorithm is able to achieve favourable and unambiguous angle estimation without any information of the gain and phase uncertainties. The effectiveness of the proposed algorithm is verified by simulation results.Introduction: Multiple-input multiple-output (MIMO) radar is characterised by using multiple antennas to simultaneously transmit orthogonal waveforms and multiple antennas to receive the reflected signals [1]. Direction of departure (DOD) and direction of arrival (DOA) have been recently investigated in [2][3][4]. All of them are based on the assumption that the transmit array and receive array steering vector are exactly known corresponding to the array geometry. But the transmit array and receive array steering vector cannot be obtained precisely when there exist gain and phase uncertainties. Therefore, the performance of the algorithms proposed in [2 -4] will seriously degrade. To deal with the problem of gain and phase uncertainties of the transmit array and the receive array, a novel ESPRIT-like angle estimation algorithm is proposed in this Letter. As there is not requirement of space searching or iterative procedure, the computational complexity is low.

A novel beamspace ESPRIT (B-ESPRIT) algorithm is proposed to estimate the direction of departures (DODs) and direction of arrivals (DOAs) for bistatic MIMO radar. It restores the rotational invariance structure lost in the beamspace transformation for both the transmit array and the receive array, and then the DODs and DOAs can be estimated through ESPRIT. The proposed algorithm can achieve a significant computational saving over the element-space ESPRIT (E-ESPRIT) algorithm for bistatic MIMO radar. Simulation results validate these conclusions.Introduction: Multiple-input multiple-output (MIMO) radar [1] can transmit orthogonal waveforms to enhance parameters, identifiability and resolution by virtual array which would greatly increase the degrees of freedom (DOF) of MIMO radar. The DOF of MIMO radar is often proportional to the product of the number of transmitters and the number of receivers, so it can be very large. In [2,3], the ESPRIT algorithm is used for direction of departures (DODs) and direction of arrivals (DOAs) estimation in bistatic MIMO radar, which necessitates eigendecomposition of the sample covariance matrix. But huge computation will be involved when the DOF is very large. Beamspace transformation is one way of reducing computation and sometimes improving the estimated robustness. As a consequence of beamspace transformation being performed, arrays such as uniform linear arrays (ULAs) would lose their rotational invariance structure. As a result, computational complexity may actually increase since the computationally efficient ESPRIT algorithm cannot be applied directly. In this Letter, we show how the beamspace ESPRIT (B-ESPRIT) algorithm exploits the beamspace invariance property of both the transmit array and receive array for DODs and DOAs estimation in the bistatic MIMO radar system. Notation: ( . ) T , ( . ) H and ( . ) * denote transpose, conjugatetranspose, conjugate operators; ⊙ and ⊗ denote the Khatri-Rao product and the Kronecker product; | . | denotes the modulus operation.