Table 2 Computational complexity

MR

0

FZF

\(\sum \limits _{n = 1}^N {\left( {\frac{{3\tau _{\mathrm{p}}^2 M}}{2} + \frac{{\tau _{\mathrm{p}} M}}{2} + \frac{{\tau _{\mathrm{p}}^3 - \tau _{\mathrm{p}} }}{3}} \right) } \times {\mathbb {I}}\left( {{\mathcal {K}}_n \ne \emptyset } \right)\)

PWPFZF

\(\begin{aligned} \sum \limits _{n = 1}^N {\left[ {\left( {\frac{{3\tau _{{\mathcal {S}}_n }^2 M}}{2} + \frac{{\tau _{{\mathcal {S}}_n } M}}{2} + \frac{{\tau _{{\mathcal {S}}_n }^3 - \tau _{{\mathcal {S}}_n } }}{3}} \right) \times {\mathbb {I}}\left( {{\mathcal {S}}_n \ne \emptyset } \right) } \right. } \\ \quad \;\left. { + 2\left( {\tau _{\mathrm{p}} - \tau _{{\mathcal {S}}_n } } \right) \tau _{{\mathcal {S}}_n } M \times {\mathbb {I}}\left( {{\mathcal {W}}_n \ne \emptyset } \right) } \right] \\ \end{aligned}\)

LRZF

\(\sum \limits _{n = 1}^N {\left( {\frac{{3M^2 \left| {{\mathcal {K}}_n } \right| }}{2} + \frac{{M\left| {{\mathcal {K}}_n } \right| }}{2} + \frac{{M^3 - M}}{3}} \right) } \times {\mathbb {I}}\left( {{\mathcal {K}}_n \ne \emptyset } \right)\)

LP-MMSE

\(\sum \limits _{n = 1}^N {\left( {\frac{{3M^2 \left| {{\mathcal {K}}_n } \right| }}{2} + \frac{{M\left| {{\mathcal {K}}_n } \right| }}{2} + \frac{{M^3 - M}}{3}} \right) } \times {\mathbb {I}}\left( {{\mathcal {K}}_n \ne \emptyset } \right)\)

Proposed combining

\(\sum \limits _{n \in {\mathcal {G}}} {\frac{{3M^2 \left| {{\mathcal {K}}_n } \right| }}{2} + \frac{{M\left| {{\mathcal {K}}_n } \right| }}{2} + \frac{{M^3 - M}}{3}}\)