Table 1 Computational complexity in term of complex multiplications

S_ref=FFT (s_ref,0)

T₀=Nlog₂N/2

S_surv=FFT (s_surv)

T₁=Nlog₂N/2

s_MF=IFFT\(\left (\boldsymbol {S}_{{surv}} \boldsymbol {S}_{{ref}}^{\ast }\right)\)

T₂=N+Nlog₂N/2

\(\phantom {\dot {i}\!} \left (\boldsymbol {S}_{r_{\varLambda }}^{H} \boldsymbol {S}_{r_{\varLambda }}\right) \)

T₃=Q²N

\(\phantom {\dot {i}\!} \left (\boldsymbol {S}_{r_{\varLambda }}^{H} \boldsymbol {S}_{r_{\varLambda }}\right)^{-1} \)

T₄=Q³

\(\phantom {\dot {i}\!} \left (\boldsymbol {S}_{r_{\varLambda }}^{H} \boldsymbol {S}_{r_{\varLambda }}\right)^{-1} \boldsymbol {S}_{r_{\varLambda }}^{H} \boldsymbol {s}_{{surv}}^{} \)

T₅=Q²

\(\phantom {\dot {i}\!}\boldsymbol {S}_{r_{\varLambda }}\left (\boldsymbol {S}_{r_{\varLambda }}^{H} \boldsymbol {S}_{r_{\varLambda }}\right)^{-1} \boldsymbol {S}_{r_{\varLambda }}^{H} \boldsymbol {s}_{{surv}}^{}\)

T₆=QN

Total complexity

\(T = {T_{0}} + k\sum \limits _{i = 1}^{6} {{T_{i}}} \)

k is the number of iterations