Time Synchronization for Wireless Sensor Networks - Adaptive Signal Processing in Wireless Communications - page 403

TPSN for large N values. Moreover, the adaptive features in AMTS make it applicable to
various different types of sensor network applications.

13.6 Conclusions

In recent years, huge attention has been paid to WSNs due to their capability of serv-
ing a variety of purposes. Time synchronization is a significant part in WSNs, and a
number of fundamental operations, like data fusion, power management, and trans-
mission scheduling, require accurate time synchronization. Since the conventional time
synchronization protocol for the Internet cannot be directly applied to WSNs, a number
of synchronization protocols have been developed to meet the unique requirements of
sensor network applications.
The importance of time synchronization also comes from the evolution of WSNs,
which has been driven by technological advances in diverse areas. For instance, unlike
the currently deployed WSNs, next-generation sensor networks may consist of dynamic
mobile sensors or a mixture of static and dynamic sensors. In this scenario, far more
sophisticated time synchronization protocols that efficiently deal with mobility of sen-
sors will be required. Indeed, as the network becomes more complicated, the role of time
synchronization becomes much more important.
In this chapter, basic features and theoretical backgrounds of the time synchroni-
zation problem in WSNs have been introduced, and three different basic approaches
are analyzed and compared to reveal the general ideas and characteristics of time syn-
chronization protocols in WSNs. In addition, a survey of existing time synchroniza-
tion protocols in the literature has been provided, including the most recent results. The
material of this chapter is presented from a signal processing viewpoint, which makes
it distinguishable from other existing surveys. Furthermore, we shed light on adaptive
time synchronization schemes for WSNs because of their huge benefits and flexibility to
topology changes. We believe that the analysis and summary in this chapter will assist
researchers in this area to select and develop more powerful synchronization protocols
tailored specifically to the needs of their applications.

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