Algorithm 1 Location Refinement

Input: ${\widehat{d}}_{ij}$ and ${\delta }_{ij}$

Output: Location of node i

While (T > 0 and $\overrightarrow{F}$ < ω2)

Location initiation; //centroid algorithm

While ($\overrightarrow{F}$ < ω1) node i updates its location according to step size calculated by ${\overrightarrow{f}}_{ij}$;

node i updates its location according to step size calculated by ${\overrightarrow{f}}_{ij}^{\prime }$;

end;