Algorithm 1 Node assignment algorithm
1:	For each ${\sigma }_i^j$| $j from 1 to n_i$//collect all the nodes whose aggregation queue is ready to aggregate.
2:	If $l({\sigma }_i^j)\ge N{t}_i^j$ or $t({\sigma }_i^j)\ge T{t}_i^j$ then
3:	${\sigma }_i^j\in {\mathsf{\Sigma }}_i$
4:	End if
5:	End for
6:	If${\mathsf{\Sigma }}_i=\varnothing$then//if ${\mathsf{\Sigma }}_i=\varnothing$, no node in $L_i$ send the aggregation queue.
7:	Return
8:	End if
9:	For each ${\sigma }_{i-1}^k|k from 1 to n_{i-1}$//collect all the nodes whose $\mathsf{\Omega }\le {\omega }_{i-1}^k<1$.
10:	If $\mathsf{\Omega }\le {\omega }_{i-1}^k<1$ then
11:	${\sigma }_{i-1}^k\in {\mathsf{\Sigma }}_{i-1}$
12:	End if
13:	End for
14:	For each ${\sigma }_{i-1}^{k^{\prime }}|$ from ${\sigma }_{i-1}^{k^{\prime }}$ with max ${\omega }_{i-1}^{k^{\prime }}$ to ${\sigma }_{i-1}^{k^{\prime }}$ with min ${\omega }_{i-1}^{k^{\prime }}$ in ${\mathsf{\Sigma }}_{i-1}$//assign ${\sigma }_i^{j^{\prime }}$ to ${\sigma }_{i-1}^{k^{\prime }}$ with the priority of large ${\omega }_{i-1}^{k^{\prime }}$ to small.
15:	While $l({\sigma }_{i-1}^{k^{\prime }})<N_t\mathrm{and}{\mathsf{\Sigma }}_i\ne \varnothing$ then //assign ${\sigma }_{i-1}^{k^{\prime }}$ with sufficient aggregation queues to make the node aggregate.
16:	$l({\sigma }_{i-1}^{k^{\prime }})=l({\sigma }_{i-1}^{k^{\prime }})+l({\sigma }_i^{j^{\prime }})\ast \mathsf{\lambda }$
17:	${\sigma }_i^{j^{\prime }}\notin {\mathsf{\Sigma }}_i$
18:	End while
19:	${\sigma }_{i-1}^{k^{\prime }}\notin {\mathsf{\Sigma }}_{i-1}$
20:	End for
21:	If${\mathsf{\Sigma }}_i\ne \varnothing$then//the remaining queues of nodes in ${\mathsf{\Sigma }}_i$ are transmitted to $\tau ({\sigma }_i^j)$.
22:	While ${\mathsf{\Sigma }}_i\ne \varnothing$ then
23:	$l(\tau ({\sigma }_{i-1}^{j^{″}}))=l(\tau ({\sigma }_{i-1}^{j^{″}}))+l({\sigma }_i^{j^{″}})\ast \mathsf{\lambda }$
24:	${\sigma }_i^{j^{″}}\notin {\mathsf{\Sigma }}_i$
25:	End while
26:	End if