  In the wireless sensor networks composed of battery-powered sensor nodes, one
of the main issues is how to save power consumption on each node. The usual
approach to this problem is to activate only necessary nodes (e.g., those nodes
which compose a backbone network), and to put other nodes to sleep. One such
algorithm using location information is GAF (Geographical Adaptive Fidelity),
and GAF is enhanced to HGAF (Hierarchical Geographical Adaptive Fidelity). In
this paper, we study the energy-efficient partition of a 3 dimensional sensor
field into cells. Further, we give a theoretical upper bound on cell size for
this problem.
