Abstract:

In many sensor network applications, data need tune stamps to record me moment of prooucmg me uata. Time stamps are indispensable for packet scheduling and other time-related tasks. The paper proposes a method of time stamping without the requirement of time synchronization. The time stamp of a datum   records the time span from the moment when the data is produced to the moment it arrives at the destination. The destination node of a datum can obtain   the moment of the datum＇s production by its clock of the datum＇s arrival minus the time stamp on the datum. In the proposed method,the inaccuracy of t the time record mainly comes from the indeterminate wireless communication delay. Estimation based on the measurement of communication delay is used to  compensate the inaccurate time record. Theoretical analysis proves that the method is superior to the existing methods on both expense and accuracy. Our  experiments on UC Berkeley Micaz within the TinyOS framework show that the time stamp method can achieve the average accuracy of one clock tick per hop  in multiple-hop sensor networks.

Key words: sensor network, time stamping, delay measurement