TOPICS IN AD HOC AND SENSOR NETWORKS

obile and wireless networks are widely recognized as the means to realize the vision of ubiquitous computing, as well as a powerful means of monitoring events and environments over large areas and long periods of time. They perfectly suit both static and dynamic scenarios, as well as several critical application scenarios. The Series on Ad Hoc and Sensor Networks of IEEE Communications Magazine started an interesting debate on research methodologies and approaches in the April 2007 issue. Theoretical research and simulation studies are fundamental for understanding the behavior of phenomena, and their relevance is even higher in such areas as wireless and mobile networking, where experimentation is not easy to realize. However, there is a need to conduct these studies in a very solid convincing way. In the past issue we discussed the importance of considering realistic scenarios, since otherwise the results may lead to conclusions that will not be confirmed in real experiments. In this issue we continue this discussion by presenting other related aspects, such as the role of information theory and simulation, as well as the introduction of novel approaches such as knowledge exploitation to coordinate mobile and wireless networks. This issue presents three articles dealing with the need for a network information theory, a proper approach to simulation, and innovative approaches that can coordinate mobile and wireless networks while taking into account dynamic network performance. We argue that these articles are very pertinent to the real development of wireless networks, and can eventually lead to industrial development and commercial applications. Understanding the performance limits of mobile and wireless networks, in particular in terms of network capacity, is essential to removing barriers to the growth and development of commercial wireless networks, including emergency, military, sensor, and community mesh networks. Information theory can provide the necessary scientific foundation for this development, as it has done in the past in some of society’s most advanced and beloved technologies, including computers, cellular phones, and the Internet. Jeff Andrews, Nihar Jindal, Martin Haenggi, Randy Berry, Syed Jafar, Dongning Guo, Sanjay Shakkottai, Robert Heath, Michael Neely, Steven Weber, and Aylin Yener identify the three main roadblocks that have so far prevented information theory from truly characterizing the limits of deployed mobile ad hoc networks (MANETs). The article describes some of the shifts in thinking that may be needed to overcome these roadblocks and develop a more general theory. The article by Ivan Stojmenovic naturally continues this argument by discussing the key points in carrying out a proper and effective simulation activity for protocol design. Network simulation studies have been criticized for their lack of proper lower-layer modeling and statistical validity, and for producing results that are not repeatable. The author presents a more general view of simulation as support for new ideas and theories, providing a platform on which to compare these new proposals with truly competing existing solutions. This goes beyond merely validating the new proposals. The article discusses the role of simulation to produce a proof of concept, how variables must be selected to be valid for a variety of heterogeneous scenarios, and notes that simplicity of design is