Hybrid Cramér-Rao bound for joint estimation of target and ionospheric parameters using MIMO-OTH radar

Exploiting the received signals, which are usually not employed in the traditional OTH radar for ionospheric parameter estimation, we study joint estimation of target and ionospheric parameters for multiple-input multiple-output skywave OTH (MIMO-OTH) radar. We employ a parabolic layer model to characterize the ionospheric distortions. We model the target and ionospheric parameters as deterministic and random unknowns, respectively, and carry out the joint estimation using a hybrid maximum likelihood and maximum a posterior (ML/MAP) method. The corresponding hybrid Cramér-Rao bound (HCRB) is derived. We show that the proposed joint estimation approach leads to an improved accuracy for the target and ionospheric parameter estimation compared with the traditional methods.