Algorithm 1 Relay Decision (RD) Algorithm for Forming Topology

1: input one value as the iteration time $irt$

2: For $i\in S/\left\{hub\right\}$

3: $r_i=hub$; //initialize a star network topology

4: $cad\left(i\right)=S/\left\{i,hub\right\}$; //obtain relay candidates

5: End

6: While $irt\ne 0$

7: sort elements in $S/\left\{hub\right\}$ into a queue $Q$ in an ascending order of distance

8: While $Q$ is not empty

9: pull out the head $i$ of $Q$;

10: For $j\in cad\left(i\right)$

11: assume an established link$\left(i,j\right)$ for transmission;

12: compute the optimized power $P_{i,j}^{opt}$;

13: compute the candidate assessment function $Se{l}_{i,j}$;

14: End

15: choose node $r_i$ as the relay of $i$ that satisfies $Se{l}_{i,r_i}=\max \left\{Se{l}_{i,j}\right\}$ where $j\in cad\left(i\right)$

16: End

17: $irt=irt-1$;

18: End