Algorithm 2. Proposed RAB method.

1: Calculate the SCM $\widehat{\mathit{R}}$ using (8) and eigen decompose $\widehat{\mathit{R}}$ to obtain ${\mathit{U}}_S$ and ${\tilde{\sigma }}_n^2$; 2: Obtain the blocking matrix $\mathit{G}$ using (13) and the projection matrix $\mathit{\Phi }={\mathit{U}}_s{\mathit{U}}_s^H\mathit{G}$; 3: Eigen decompose $\mathit{\Phi }$ to obtain ${\mathit{B}}_s$ and reconstruct INCM via (17); 4: Using the iterative mismatch approximation method in Algorithm 1 to estimate the SOI SV; 5: Substitute ${\tilde{\mathit{R}}}_{i+n}$ and ${\tilde{\mathit{a}}}_0$ back into (20) to obtain the weight vector.