Scheduling Sensors by Tiling Lattices
  Suppose that wirelessly communicating sensors are placed in a regular fashion on the points of a lattice. Common communication protocols allow the sensors to broadcast messages at arbitrary times, which can lead to problems should two sensors broadcast at the same time. It is shown that one can exploit a tiling of the lattice to derive a deterministic periodic schedule for the broadcast communication of sensors that is guaranteed to be collision-free. The proposed schedule is shown to be optimal in the number of time slots. 
Andreas Klappenecker, Hyunyoung Lee, Jennifer L. Welch (Texas A&M   University)