Fine-Grained Time Synchronization for Mission-Critical DTSNs

It is generally considered a trivial task to synchronize time in a distributed sensor network having a GPS module on board for each sensor node. This is not quite true depending on the application at hand. Commissioned to implement YuShanNet, a Delay-Tolerant Sensor Network (DTSN) enabling encounter information collection for hiker search and rescue, the authors find that the naive use of standard GPSs time acquisition functionalities gives a synchronization error at the scale of 10- 100s milliseconds, which is not sufficient given two application-specific considerations: data goodput and energy efficiency.