“…They are modeled as zero-mean complex Gaussian random variables with variances σ 2 s1,ri and σ 2 ri,s2 respectively, and it is also assumed that the channels are symmetrical, which means that the channel coefficients of both directions between the two corresponding nodes are the same, which is a common assumption in two-way networks investigated in Refs. [6,[16][17][18][19][20][21]. So the signal to be forwarded by R i can be expressed as…”