Special issue: Mobile ad hoc networking—research, trends and applications

Abstract

Tertio millennio ineunte (at the dawn of the third millennium) it is clear that wireless communications are the natural form of communication among people and even things. Virtually every appliance is equipped with a small, cheap, lightweight wireless interface and the possibility of communicating anytime, from anywhere, to anybody/anything, in the world and beyond, is imminent. In the field of wireless communications and mobile computing, mobile ad hoc networks have received great attention recently. Research into ad hoc networks began in the early 1980s as DARPA packet radio networks. Ad hoc networks operate without any central administration (i.e., base stations and mobile switching centers). Because of its independence from fixed infrastructure, ad hoc networking is considered as the most promising network architecture to enable the ‘many any communications.’ The lack of infrastructure in ad hoc networks, which differentiates ad hoc networks from cellular networks, raises several research challenges. Each network node must act as a router and packet forwarder. Each node communicates via wireless radios that have limited transmission radius. If a node wishes to communicate with another node that is not within its transmission range, it must build a multihop route and rely on intermediate nodes to forward the packet. In addition, each node is mobile and hence the network topology constantly changes in an unpredictable manner. These challenges of ad hoc networks in combination with those of traditional wireless networks (e.g., limited bandwidth, power constraints, security, limited storage) make ad hoc networking research interesting and challenging. Ad hoc networks are deployed in places where it is impossible or difficult to build an infrastructure because of cost, security, and timeliness. Examples of these situations are mostly emergency and military scenarios such as search and rescue, battlefield, and disaster recovery. In recent years, new ad hoc networking technologies, Bluetooth for instance, have emerged and enable personal area networks and home networks to be new application areas of wireless mobile ad hoc networks. With this special issue we bring together seven papers that represent state-of-the-art contributions. The papers published in this issue range from papers that thoroughly survey advanced technologies to papers that report cutting-edge research to papers that describe industrial experiences. The first paper is authored by one of the pioneers in ad hoc networking research, Anthony Ephremides. His paper looks back at the history of ad hoc networks and the growth of this research field. Current research problems are also highlighted in this article. The paper by Bisdikian et al. describes recent mobile communications projects by IBM T.J. Watson Research Center. Their work on Bluetooth technology, BlueDrekar software stack based on Bluetooth specification, and WebSplitter middleware that enables web browsing in multiple devices are introduced. Their interesting vision of tomorrow's web in connected devices is also shared in this paper. The paper by Charles Perkins et al. reports connecting the AODV (Ad hoc On-demand Distance Vector) protocol to the IPv6 Internet. Several technologies are required to achieve this: general Internet gateway connectivity, address auto-configuration, mobile IPv6, changes to router advertisement, changes to treatment of default routes, and multi-gateway operations. These innovations are illustrated in this paper. The following two papers are survey papers. Camp et al. review the mobility models used in ad hoc networking simulations. They categorize the mobility models into entity models where each node's movement is independent of other nodes and group models where a number of nodes in a group share similar mobility patterns. The impact of the selection of mobility models on ad hoc networks performance is studied through extensive simulations. Achieving QoS in ad hoc networks is a difficult task. Perkins and Hughes survey the recent work in this area. They examine the research area in three components: routing, resource reservation, and MAC. The authors also give insights and suggestions for future work for QoS research in ad hoc networking. The paper by Belding-Royer proposes a new hierarchical routing scheme for ad hoc networks called Adaptive Routing along Clustering (ARC). This protocol increases routing flexibility, robustness, and scalability. ARC uses limited broadcasting to minimize the control message overhead. The simulation results show that when combined with AODV, ARC performs favorably over other clustering algorithms. Finally, Kong et al. describe an adaptive security framework for military wireless networks with Unmanned Aerial Vehicles (UAVs). When mobile backbone infrastructure is available, UAVs perform authentication for security services. When the infrastructure is absent, their system localizes the security services at each node for ad hoc communications mode. The paper reports results from their testbed and simulation implementations. We thank the WCMC Editor-in-Chief Mohsen Guizani for his support and the staff at Wiley (Mark Hammond, Laura Kempster, and Claire Bailey). Our deep gratitude also goes to over sixty reviewers for their excellent and detailed reviews. We also thank the authors of all the submitted papers. Enjoy the issue!