Identifiability Analysis of Local Oscillator Phase Self-Calibration Based on Hybrid Cramér–Rao Bound in MIMO Radar

The identifiability of self-calibration of local oscillator phase perturbation in multiple-input multiple-output (MIMO) radar is analyzed in this paper. Four cases are considered: the absolute phase perturbation (APP) and phase perturbation differences (PPDs) in MIMO radar with widely separated antennas (SMIMOR), and the APP and PPDs in co-located MIMO radar (CMIMOR). The tightness of the hybrid Cramér-Rao bound (HCRB) is proved in all four cases. It is interesting that the problem in this paper is a special case in which HCRB is asymptotically tight for nonlinear observation models containing unknown deterministic and random parameters. For each case, a signal model for multiple stationary targets is constructed. The closed-form HCRB of phase perturbation is derived and used to analyze the identifiability of phase perturbation. It is proven that only the PPDs in CMIMOR in the above-mentioned four cases are identifiable. Numerical simulations verify the conclusion.