Thanks to key advances in wireless communication and electronics, sensors have emerged as an appealing technology for several interesting applications, such as civilian (health and environment monitoring), natural (disaster detection), military (battlefield surveillance), and agricultural (precision agriculture) applications, to name a few. When grouped together, these sensors form a network to measure and gather data of the surrounding environment with respect to a specific phenomenon. The sensors are battery-powered, tiny devices that possess all the characteristics of a traditional computer, including storage, processing, and communication capabilities. In addition, these sensors are capable of sensing the environment and collecting data regarding several parameters, such as temperature, light, sound, vibration, etc. Unfortunately, all the sensors' capabilities are limited due to their physical size. In particular, the sensors have limited battery power as usually they are equipped with AA/AAA batteries whose lifetime is short. Therefore, the main challenge in the design of this type of network is the sensors' battery power (or energy), which is a critical component for the operation of the whole network. Moreover, these sensors communicate (possibly) wirelessly with each other to collect sensed data and accomplish the goals of their missions. To this end, the sensors are required to know their locations and those of their neighbors. Therefore, sensor localization is a crucial aspect for the design and development of wireless sensor networks. Various algorithms and protocols have been developed for sensor localization in both two-dimensional and three- dimensional wireless sensor networks. However, the problem of sensor localization in a three-dimensional space has not been investigated in the literature as extensively as its counterpart in a two-dimensional space. In this book chapter, we propose to study the sensor localization problem in three-dimensional wireless sensor networks. More precisely, this book chapter's sole focus will be on three-dimensional sensor deployment, and it aims to provide an overview of the existing solutions to the localization problem in a three-dimensional space. Basically, it proposes a classification of localization algorithms, and discusses different three-dimensional sensor localization approaches along with their motivation and evaluation.
Improved Virtual Potential Field Algorithm Based on Probability Model in Three-Dimensional Directional Sensor Networks
