\left| {{B}_{{{R}_{j}}}}\left( {{\pi }_{S}} \right) \right| \right) \\   & =\left( 0-\tfrac{L}{N} \right)\tfrac{{{\left| {{B}_{{{R}_{j}}}}\left( {{\pi }_{S}} \right) \right|}^{0}}}{\left| {{B}_{{{R}_{j}}}}\left( {{\pi }_{S}} \right) \right|+\left( D\left( {{\pi }_{S}} \right)\left| {{B}_{{{R}_{j}}}}\left( {{\pi }_{S}} \right) \right| \right)},   \end{split}$$ 