Problem Solving for Wireless Sensor Networks

Many wireless monitoring and control applications are available for the industrial and home markets. Some hardware platforms are specialized for optimizing only one feature (e.g., high data rate, long transfer range, or low-power mode). However, the most restrictive parameters for WSNs are both power consumption and distance. This chapter briefly describes different radio-frequency technologies, although many of them are not appropriate or are not yet fully developed for WSNs. Therefore, only appropriate technologies are discussed in depth, and a brief overview of several integrated circuits from different manufacturers is included.

Many different manufacturers have complete wireless sensor nodes and solutions available. This chapter describes the current main WSN platforms, ranging from systems with radio-frequency bands of 300 MHz to those platforms using a 2.4-GHz radio-frequency band. Much of the information is presented in tabular form to ease comparison between platforms and to have the data in a uniform format. This information has been compiled from a variety of sources, including product brochures and manufacturers’ Web pages. To obtain more detailed information on any product, we highly recommend consulting the references at the end of the chapter or directly contacting the manufacturer.

WSNs pose many challenges to the software applications that run on them. It is not only the scarcity of nodes’ resources, but also the particularities of the WSN applications that make software design and development in WSN an open research issue. This chapter reviews some of the most significant software-related aspects of WSNs that are currently the object of intensive research, namely middleware for WSNs, the applicability of agent technologies to WSNs, and design strategies for and the operation of WSN software. We also review WSN simulation platforms. Although they are not software to be run on top of a WSN, these platforms are a key element when devising new protocols or solutions for this technology, as they eliminate the need to deploy a real WSN network from the beginning.

Wireless sensor networks have been found to be very useful for many military and civil applications such as disaster management, surveillance of battle fields, and security. In many of these environments, the sensor nodes are strongly limited in terms of energy since their batteries usually cannot be recharged. Thus, designing energy-efficient algorithms has become an important factor to lengthen the lifetime of WSNs. Efficient network deployment and management is crucial to set an acceptable quality level in the network operation and to preserve as much of the node energy as possible. Correct energy management assures the desired performance level for data transmissions while lengthening the lifetime of the network. Energy restrictions combined with wide-scale deployments make implementing energy-saving methods necessary in most protocols, including the network and MAC layers. Energy-efficient routing can optimize the lifetime of the network by selecting paths that expend less energy, whereas collision suppression and decreasing energy consumption in the receiver must be the goals of the different Medium Access Control (MAC) mechanisms. Since energy considerations have dominated most of the investigations about WSN network operation and deployment, quality-of-service (QoS) issues such as latency, throughput, delay, or jitter have not been treated with great detail until now, topics that have been identified as interesting open issues for further research.

The use of any technology requires that its users be confident of both its usefulness and its safety. In an effort to guarantee this, standardization bodies around the world generate standards to be followed by product manufacturers. When dealing with electronic communications systems such as WSNs, issues such as electromagnetic compatibility, the safety of their operation, the confidentiality and security of private information, and environmental awareness are of great practical importance. This chapter reviews how these safety issues apply to WSNs and presents some of the significant European regulations on this matter together with some notes on the open issues that may have to be treated in possible future standards.

We summarize some relevant research European projects to give the reader a picture on the work in progress in the industrial and academic communities regarding WSNs. For each project we have included a list with basic information (useful if more data on the project are sought) and a summary of the main project objectives. The large number of projects whose research objectives fall into WSNs (in whole or in part) also gives an idea of the high current interest in this technology.

Wireless sensor network (WSN) technology is a new and modern technology that has already been implemented in a wide variety of scenarios, and its applications are growing every day. As models for mobile wireless networking become more popular, their appeal comes from the fact that they can operate autonomously without the need for an existing infrastructure. This great benefit can be seen even more clearly when looking at the many problems that the use of WSN technology solves. The applications of WSN technology have been classified into four main categories: environmental monitoring, health care, security, and additional applications. After we review the different WSN cases in these fields, we identify three of the most demanding and most representative scenarios to demonstrate the advantages of WSN technology and its boundless potential in today’s world. The technical analysis defines the use cases for multiple-target tracking, surveillance and vital sign, and environmental critical monitoring and specifies the user requirements and technical description of the network infrastructure and overall system that should be designed to support all three application scenarios.