The most difficult problem in operating synchronized MAC protocols is to maintain tight time synchronization among nodes.
This necessitates algorithms that achieve and maintain global time synchronization at all network nodes, that is, algorithms that align all nodes to a common notion of time.
In a variety of applications, sensor nodes are required to maintain accurate time synchronization, for example, moving object tracking, reconnaissance and surveillance, environmental monitoring, and so forth [1].
This necessitates network algorithms that achieve and maintain global time synchronization at all network nodes, that is, algorithms that align all network nodes to a common notion of time.
In a variety of applications, these sensor nodes are collectively required to maintain accurate time synchronization, for example, moving object acquisition and tracking, habitat monitoring, reconnaissance and surveillance, environmental monitoring, traffic control, and so forth [1].
In order to limit the impact of statistical jamming but still benefit from the above energy and timeliness performance, we maintain the time synchronization but change the schedule, transmission duration, and routes in a randomized yet coordinated manner along small time scales.
The data logger maintains the time synchronization using a GPS and an atomic clock module (SA.45 s CSAC) from Symmetricom.
Such simple and repetitive patterns are maintained with tight time synchronization and result in minimal energy consumption, deterministic end-to-end delay, and perhaps maximal transmission concurrency.
Time synchronization is maintained using SYNC messages exchanged during active period.
Time synchronization is maintained in the main processor based on time received according to the NTP (network time protocol) through communication with an internet time server.
