Topics in ad hoc and sensor networks

ireless ad hoc and sensor networks are considered the most interesting evolution of network communications. They are, however, highly evolved from their initial designs, and cover a very large number of applications and communications scenarios. While several researchers are still investigating efficient routing algorithms in a fully self-organized scenario, other research is moving toward the integration of flexible and self-organized networks with fixed IP. They demonstrate their flexibility as the only technology that can be applied in a very opportunistic way, exploiting every available communication possibility. These evolutions are perfectly suited to the large number of scenarios we are going to face in the pervasive world. Wireless sensor networks further increase these capabilities, being a very effective technology for the retrieval of large quantities and high quality of data over long periods of time. Therefore, the self-organized networks covers most of the more critical application scenarios ranging from military and environmental to personal and in-house . Currently, they are starting to also be proposed for data hungry applications, based on object tracking and event identification. As in previous issues, we are very proud to host in this issue a set of articles that survey and discuss some interesting aspects of this very promising field. The Series on Ad Hoc and Sensor Networks of IEEE Communications Magazine has already provided very important articles on the latest developments in this very rich and exciting domain, proposing itself as a very important forum for wireless and mobile networking. The current issue presents four articles that discuss seminal research in this field dealing with innovative challenging aspects of the domain. The main focus of the research in mobile ad hoc networks (MANETs) and sensor networks was and is still the design problem of efficient routing algorithms that can be efficiently applied to several scenarios and applications. However, despite the great efforts expended, existing monolithic solutions can hardly meet this target. The article by M. J. Lee, X. Hu, H. Juan, C. Zhu, and J. Zheng, starting from this observation, proposes a different approach to routing in wireless multihop ad hoc networks. They design a component-based routing protocol where each routing component is represented by a building block. By doing so, the authors argue that it is easier to adjust to the requirements of different scenarios and applications. Rui Teng discusses, in his article, hybrid ad hoc networks where nodes can communicate directly in an ad hoc way, but also via the wired infrastructure. Routing in this scenario can be very different from both traditional MANETs as well as the Internet. The author introduces a new routing algorithm designed specifically for this scenario and presents its evaluation via simulation. The article by Luciana Pelusi, Marco Conti, and Andrea Passarella presents the main challenges and design options of one of the most interesting evolutions of MANETs: opportunistic networks, where the communication between two nodes can happen even if a route connecting them never exists. Any node is opportunistically used as a next hop, provided it is likely to bring the message closer to the final destination. The authors provide a survey of the most interesting case studies in opportunistic networking, along with a taxonomy and a discussion of the main approaches to routing and forwarding in this challenging environment. Finally, the article by Yonghe Liu and Sajal Das presents the design principle of a sensor network for information-rich data applications. The authors present potentials and applications of such a class of sensor networks, which is dramatically distinguished from traditional current sensor networks. They identify the key challenges stemming from system uncertainties unique to video sensor networks related to networking, security, sensor design, and video data analysis. The guest editors are, as usual, very grateful to the authors who have submitted papers and those who agreed to present their work in this issue of the Series on Ad Hoc and Sensor Networks of IEEE Communications Magazine. They would also like to express their sincere thanks to all the reviewers for their tremendous effort in supporting the issue, and whose very critical and helpful comments and suggestions have helped achieve such high quality in the published articles. Special thanks to the editorial team for their invaluable support.