As part of our continuing research, we plan to re-implement our time synchronization experiment on hardware that is more akin to hardware that will be found in sensor networks: slower, lower-power nodes that have wireless radio links. While using PCs with wired stimuli and event delivery did provide an important proof-of-concept, we wish to investigate the effects on precision of factors such as slower clock speeds, variable latency of radios, and nondeterminism introduced by radio propagation anomalies. We plan to do these tests using the wireless sensor network testbed in place as part of the related SCADDS project [4].
In addition to characterizing post-facto synchronization, we plan to use it in the context of a real application: localization. Building on Girod's prototype acoustic rangefinder [5], we plan to use post-facto time synchronization to facilitate measurement of the time of flight of sound from an audio source to a set of receivers, allowing them to trilaterate with high precision.
We also plan to build on this work by developing additional time sync methods with the ultimate goal of providing a palette to applications that covers a good portion of the parameter space we described in of the parameter space we described in Section 2. Because it is impossible for any single synchronization method to appropriate in all situations, sensors should have multiple methods available. If a node can dynamically trade precision for energy, or scope for convergence time, it can avoid ``paying'' for something that it doesn't need. Ideally, the algorithms should also be tunable--allowing finer control over an algorithm than simply turning it on or off.