Fig. 10
From: Geographical model-derived grid-based directional routing for massively dense WSNs
Sequence diagram for 
in the iteration of DGSI-FEM. For example, in the forward sweep, 
and 
update and then send their \(\widetilde {\Phi }\)s and DONEs to 
After updating \(\widetilde {\Phi }_{{i},{j}}\) and DONE
i,j
, 
sends \(\widetilde {\Phi }_{{i},{j}}\) and DONE
i,j
to 
and 
. The dark rectangles drawn on top of the lifelines indicate that grid points are updating \(\widetilde {\Phi }\)s and DONEs (or PRECISEs in the backward sweep)