Joint Estimation of MIMO-OTH Radar Measurements and Ionospheric Parameters

To avoid the disadvantage of the traditional over-the-horizon (OTH) radar, which uses only the measurements of ionospheric parameters obtained from an ionosonde to estimate the target parameters, this paper proposes a new multiple-input multiple-output skywave OTH radar, which estimates the ionospheric and target parameters jointly by exploiting the data received by both the ionosonde and the radar receivers. First, we consider the scenario where the prior distribution of ionospheric parameters is unknown, the joint maximum likelihood estimator is developed and the Cramér–Rao bound (CRB) is derived to analyze the estimation performance. Then, the case with known Gaussian ionospheric prior distribution is analyzed, we develop the hybrid maximum likelihood and maximum a posteriori estimator, and the hybrid CRB (HCRB) is derived for analyzing the estimation performance. Finally, we show that the proposed joint estimation approaches lead to better accuracy for the ionospheric and target parameters estimation. We prove that both the CRB and the HCRB vary with the ionosonde measurement error covariance, and the corresponding upper and lower bounds are derived.