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Clustering of nodes provides an efficient means of establishing a hierarchical structure in mobile ad hoc networks. In this paper, we introduce two new stability-driven clustering algorithms for pseudolinear highly mobile ad hoc networks such as that of communication between aircraft, ships, trains, and cars on highways. The new algorithms aim at establishing stable clusters, where clusterhead reelection is reduced, and cluster membership periods are increased in the targeted system. The first algorithm is used for scenarios where the position information of nodes is not available, and the second algorithm is aimed at scenarios where position information is available [e.g., nodes are equipped with the Global Positioning System (GPS)]. The algorithms involve dynamic clusterhead election, and the scheme incorporates cluster maintenance to cater to changes in network topology as time progresses. Simulations show that the proposed clustering algorithms provide highly stable clusters with several advantages over previous one-hop clustering schemes. Index Terms--Aeronautical ad hoc networks, clustering methods, hierarchical routing, stable clustering.

There are numerous research challenges that need to be addressed until a wide deployment of vehicular ad hoc networks (VANETs) becomes possible. One of the critical issues consists of the design of scalable routing algorithms that are robust to frequent path disruptions caused by vehicles' mobility. This paper argues the use of information on vehicles' movement information (e.g., position, direction, speed, and digital mapping of roads) to predict a possible link-breakage event prior to its occurrence. Vehicles are grouped according to their velocity vectors. This kind of grouping ensures that vehicles, belonging to the same group, are more likely to establish stable single and multihop paths as they are moving together. Setting up routes that involve only vehicles from the same group guarantees a high level of stable communication in VANETs. The scheme presented in this paper also reduces the overall traffic in highly mobile VANET networks. The frequency of flood requests is reduced by elongating the link duration of the selected paths. To prevent broadcast storms that may be intrigued during path discovery operation, another scheme is also introduced. The basic concept behind the proposed scheme is to broadcast only specific and well-defined packets, referred to as 'best packets' in this paper. The performance of the scheme is evaluated through computer simulations. Simulation results indicate the benefits of the proposed routing strategy in terms of increasing link duration, reducing the number of link-breakage events and increasing the end-to-end throughput. Index Terms--Intervehicular communications (IVC), road-vehicle communications (RVC), stable routing, vehicular ad hoc network (VANET).

In this paper we propose an energy-efficient self-organizing global extremity reporting scheme for wireless sensor networks. The proposed scheme assists applications of periodic reporting of extreme values (such as maximum or minimum temperature/pressure) across a wireless sensor field, back to the sink. Furthermore, an event-driven counterpart is supplied for individual sensor nodes to supply their instantaneous sensed values back to the sink, once queried. The targeted sensors initially establish their relative distances to the sink in regards to number of hops, whilst the highest hopcount nodes (HHNs) from the sink identify themselves. The broadcast initiation of the HHNs have the ability to penetrate all nodes within the network towards the sink, and hence obtain the extreme value of the entire network in an efficient manner. This is due to the relative position of these special nodes within the network. Furthermore, the scheme does not require nodes to possess location information of themselves or other nodes, avoiding the need for the global positioning system (GPS) or other location-aware methods. Simulation results show the effectiveness of the proposed protocol in its target application. In particular, the advantage of HHN-initiated broadcasting can be seen in both uniformly and randomly distributed topology networks. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, the concept of a new form of mobile network formed in the sky is introduced, where the mobile routers are simply the commercial aircraft. This implementation aims to eliminate two main problems arising from the current in-flight broadband implementation. The first problem is the resource management issue that may arise from the rapid increase of in-flight broadband Internet use in the near future. This could consequently limit current satellite resources, and bandwidth. The other issue is the inherent problem associated with Internet use over satellite, such as the degraded performance of delay sensitive applications due to the long propagation delay of a satellite link. A system model for data access, stable clustering of aircraft, and efficient routing schemes are introduced, which are suitable for the aeronautical mobility model. Link stability is predicted by a novel approach using Doppler shift subjected to control packets to dynamically form stable clustering and routing protocols. Another aim of this paper is to show that relative velocity between nodes is adequate as a stability metric, dominating relative distance, and this becomes evident in the simulations presented. An outline of how the new system could potentially interact with the traditional Internet using Mobile IP is also briefly discussed. [ABSTRACT FROM AUTHOR]