Range-Angle Estimation Using FDA-MIMO Radar With Inter-Pulse Coding Modulation

Conventional multiple-input and multiple-output (MIMO) radar with frequency diverse array (FDA) has capability of resolving range ambiguity, however, it lacks range resolution of targets within an identical range cell. Considering this case, the FDA-MIMO radar employing the large frequency offset and inter-pulse coding modulation scheme, which is named the enhanced FDA-MIMO radar in this paper, is explored to resolve range ambiguity and estimate target parameters. Large frequency offset causes the signals of different antennas to occupy different frequency bands. Besides, the orthogonal polyphase codes among pulses are utilized to distinguish range ambiguous targets. Therefore, the proposed framework is advantageous in separating range ambiguity echo and realizing high resolution of target. To further resolve the targets within a range cell, a two-stage estimation method for angle and the principal range difference with the maximum likelihood estimator (MLE) is proposed. Finally, we firstly study the Ziv-Zakai bound (ZZB) and the Cramér-Rao bound (CRB) for the enhanced FDA-MIMO radar, which are performed to assess the estimation performance of the proposed method. Extensive simulations are implemented to demonstrate that the enhanced FDA-MIMO radar is superious in terms of range resolution and range ambiguity resolution.