Algorithm 1. Optimizing the Position of the Cluster-in Nodes.
Input: set of cluster-in nodes Sc(sk), original position of the cluster-in nodes Po(sk). Output: deployed position of the cluster-in node Pd(sk). 1: Initialize Pd(sk) = zeros(|Sc(sk)|, 3), SND, SCD = sk; 2: while Sc(sk) $\ne \varnothing$ 3:   calculate the CRR of the node in Sc(sk); 4:   si = the node with the minimum CRR; 5:   poriginal(si) = [xoriginal, yoriginal, zoriginal] according to Po(sk); 6:   assuming that pdeployed(si) = [xdeployed,ydeployed,zdeployed] and build the fitness function; 7:   initialize N1, N2, Np, G, and the search range; 8:   initialize the position Xj and the speed Vj of each pigeon individual j; 9:   calculate the fitness2 of each pigeon individual; 10:   Xg = arg min[fitness2(Xj)]; 11:   for Nt = 1 to N1 do 12:     for i = 1 to Np do 13:       calculate Vi and Xi according to Equations (8) and (9); 14:     end for 15:     evaluate Xi, and update Xg; 16:   end for 17:   for Nt = 1 to N2 do 18:     if Np > 1 19:       rank the fitness2; 20:       Np = Np/2; 21:        removed the half of pigeons with a lower fitness2; 22:       calculate Xc according to Equation (11); 23:       for i = 1 to Np do (remaining pigeons) 24:         calculate Vi and Xi according to Equation (12); 25:       end 26:        evaluate Xi, and update Xg; 27:     end if 28:  end for 29:  record Xg into Pd(sk), namely, update the value of corresponding row in Pd(sk); 30:  Sc(sk) = Sc(sk) − si; 31:  SND = SND ${\displaystyle \cup }$ si; 32:  SCD = SCD ${\displaystyle \cup }$ si; 33: end while;
	Notice: Po(sk) and Pd(sk) are the matrix with the size |Sc(sk)| × 3, and Po(sk) = [Poriginal(s1); Poriginal(s2);⋯, Poriginal(si)]. In addition, zeros(|Sc(sk)|, 3) is the matrix whose element is zero and whose size is size |Sc(sk)| × 3.