**Author details**

Giuseppe Procaccianti, Luca Ardito, Antonio Vetro' and Maurizio Morisio *Politecnico di Torino, Italy*

20 Will-be-set-by-IN-TECH 372 Energy Effi ciency – The Innovative Ways for Smart Energy, the Future Towards Modern Utilities **Chapter 0**

#### **7. References**

[1] Basili, V. R., Caldiera, G. & Rombach, H. D. [1994]. The goal question metric approach, *Encyclopedia of Software Engineering*, Wiley.

**Energy Efficiency in Cooperative**

Glauber Brante, Marcos Tomio Kakitani and Richard Demo Souza

Wireless Sensor Networks (WSNs) are composed by a large number of sensor nodes, which are usually small in size and are deployed inside or close to some phenomenon of interest. Moreover, since usually there is no need for regular or predefined deployment, the sensors can be placed over irregular or inaccessible areas. Therefore, according to [2], it is expected that the sensors possess self-organizing capabilities. Such attributes provide to the WSNs a large number of applications such as medical, military, and commercial. For instance, in medical applications wireless sensor networks can be used in patient monitoring systems. In the military, the fast set-up and self-organizing characteristics of the sensors make WSNs interesting for communication applications, security, monitoring, and terrain recognition. Commercial applications can include inventory management, product quality control and

**Chapter 18**

The nodes in a WSN are typically equipped with limited power sources such as batteries, whose recharge or replacement may not always be possible or of economical interest. Moreover, batteries capacity presented a modest increase in the last decades when compared to the gains obtained in computational capacity and wireless throughput, which motivates the study of the energy efficiency of these devices. The wireless throughput has grown by roughly one million times and the computational capacity has had an increase of 40 million times since 1957, while the average nominal battery capacity has increased only 3.5 percent per year over the last two decades, as shown in [11, 24]. Thus, according to [9], due to these power source limitations, the overall energy consumption and energy efficiency have great importance and are major concerns in the design and analysis of wireless sensor networks. Another challenge faced by WSNs is the wireless environment itself. The wireless channel is a difficult and unpredictable communication medium. A signal transmitted through wireless is subjected to many factors, such as noise, random fluctuations in time (usually referred to as fading), attenuation due to moving objects, etc. Therefore, a reliable system design comes at the expense of a significant amount of power, required to transmit a block of data from

> ©2012 Brante et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0),which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly

and reproduction in any medium, provided the original work is properly cited.

© 2012 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

**Wireless Sensor Networks**

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/47780

**1. Introduction**

monitoring disaster areas.

cited.

