**1. Introduction**

Wireless sensor networks (WSNs) have attracted a lot of recent research interest due to their applicability in security, monitoring, disaster relief and environmental applications. WSNs consist of a number of low-cost sensors scattered in a geographical area of interest and connected by a wireless RF interface. Sensors gather information about the monitored area and send this information to gateway nodes. The radio on board these sensor nodes has limited range and allows the node to transmit over short distances. In most deployment scenarios, it is not possible for each node to communicate directly to the sink and hence, the model of communication is to transmit over short distances to other peers in the direction of the sink nodes.

In order to keep their cost low, the sensors are equipped with limited energy and computational resources. The energy supply is typically in the form of a battery and once the battery is exhausted, the sensor is considered to be dead. The nodes also have limited memory and processing capabilities. Hence, harnessing the potential of these networks involves tackling a myriad of different issues from algorithms for network operation, programming models, architecture and hardware to more traditional networking issues. For a more detailed survey on the various computational research aspects of Wireless Sensor Networks, see the survey papers [2, 13, 24, 37, 39], or the more recent books [23, 28] and a special issue of the CACM [14].

This section focuses on the algorithmic aspects of Wireless Sensor Networks. Specifically, we look at the problem of covering a set of targets or an area for the longest duration possible. The next section focuses on a more detailed discussion of the problem and provides a formal statement for it. It is worth mentioning that there is an abundance of algorithmic research related to WSNs. A lot of this focuses on traditional distributed computing issues like localization, fault tolerance, robustness. This naturally raises the interesting question of how different are WSNs as a computational model than more traditional distributed computing environments or even ad-hoc networks? This question has been explored briefly in [43].

©2012 Dhawan, 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 cited. ©2012 Dhawan, licensee InTech. This is a paper 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 cited.

### 2 Will-be-set-by-IN-TECH 26 Wireless Sensor Networks – Technology and Protocols
