n this seventh issue of the Automotive Networking and Applications Series, we are pleased to present five articles that address issues related to research challenges in intervehicular communications, traffic information systems, and IP mobility support for Internet-enabled cars. Intervehicular communications (IVC) has recently attracted much attention within the networking research community. Over the past few years, significant progress has been made in new technologies for managing and

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... ling network connections among vehicles and between vehicles and communications infrastructures, to support numerous emerging applications. Given that so much has been achieved, is IVC still a worthwhile field for basic and applied research? A group of leading researchers in this field gathered at the Schloss Dagstuhl -Leibniz Center for Informatics in Germany in October 2010 to discuss the future of IVC, with a particular focus on open challenges and new research directions in IVC. The first article, "Research Challenges in Intervehicular Communication: Lessons of the 2010 Dagstuhl Seminar" by F. Dressler et al., summarizes the findings of the Dagstuhl meeting. The authors describe their findings in four broad areas: fundamental limits and opportunities in IVC, IVC communication principles and patterns, security and privacy in IVC, and IVC simulation and modeling. Vehicular ad hoc networks (VANETs) are expected to enhance driving safety and roadway traffic efficiency, and as such have received much research effort in recent years. One of the key non-safety applications of VANETs is traffic information systems, which are less delay-sensitive compared to safety applications. The second and third articles deal with issues related to the design of fully distributed traffic information systems. The second article, "Design and Evaluation of a Two-Tier Peer-to-Peer Traffic Information System" by S.-L. Tsao and C.-M. Cheng, describes architectural designs toward building decentralized traffic information systems to support traffic information services. The authors investigate existing single-tier architectures, and propose a two-tier architecture that exploits both VANETs and peer-to-peer technologies, and is shown to achieve better lookup success rate, latency, and maintenance cost than single-tier systems. The third article, "Traffic Information Systems: Efficient Message Dissemination via Adaptive Beaconing" by C. Som-mer et al., describes dissemination of information in VANETs in a completely distributed fashion, and proposes a message dissemination protocol (called Adaptive Traffic Beacon) that uses adaptive beaconing and adapts to highly dynamic communications environments according to the complementary metrics of channel conditions and message utilities, instead of using only one of these metrics. The authors further show that adaptive beaconing results in much broader dissemination of messages, an important metric for traffic information applications, while a flooding-based approach outperforms beaconing in terms of dissemination speed, an important metric for safety applications. Recent advances in computing, sensing, control, and communications technologies have contributed significantly to the emergence of networked cars and advanced applications in safety, mobility, car maintenance, passenger entertainment, and Internet-enriched applications. Vehicle-to-infrastructure (V2I) communications can enable cars to utilize a variety of wireless infrastructures to access resources and services from the Internet. The fourth and fifth articles survey existing IP mobility solutions and highlight open issues for V2I communications. The fourth article, "Supporting Mobility for Internet Cars" by Z. Zhu et al., surveys existing IP mobility solutions, analyzes different design choices, and evaluates their suitability in providing mobility support for V2I communications. The authors then highlight special requirements in automotive mobility support and open challenges. The fifth article, "IP Mobility Management for Vehicular Communication Networks: Challenges and Solutions" by S. Cespedes et al., examines the specific requirements of vehicular communications networks in terms of IP mobility support, surveys and evaluates the existing approaches to improve the performance of network mobility basic support (NEMO BS) in vehicular scenarios, and highlights remaining challenges. We thank all contributors who submitted manuscripts for this series, as well as all the reviewers who helped with thoughtful and timely reviews. We thank Dr. Steve Gorshe, Editor-in-Chief, for his support, guidance, and suggestions throughout the process of putting together this issue. We also thank the IEEE publication staff, particularly Ms. Jennifer Porcello, for their assistance and diligence in preparing the issue for publication.