Wi-Fi based broadband wireless access for users on the road

This paper considers the provision of broadband wireless access (BWA) for users on the road. A Wi-Fi based system, which utilises a three-tier network architecture, is suggested as a readily available way of achieving BWA for road vehicles. However, the use of this approach and technology still poses a number of specific challenges. We identify and examine in greater depth a number of the challenges, and propose possible solutions to overcome them.     

Future management of spectrum

As the heterogeneity of wireless access technologies increases, dynamic allocation and utilisation of spectrum become ever more important. The traditional rigid allocation of spectrum for technology-specific usage is not suitable for the increasingly dynamic demand driven by the continuous emergence of technologies providing new services with different quality of service requirements. New spectrum management techniques and increasingly flexible spectrum usage rights are therefore called for. We discuss the limitations of present spectrum management techniques and explore some new alternatives including spectrum trading and opportunistic spectrum access.     

Epidemic algorithms for reliable and efficient information dissemination in vehicular

Vehicular ad hoc networks (VANET), which are created by vehicles equipped with short- and mediumrange wireless communication, have an array of important applications in intelligent transport systems. Many of these applications require reliable, bandwidth-efficient dissemination of traffic and road information via ad hoc network technology. This is a difficult task since inter-vehicular networks often lack continuous end-to-end connectivity and are characterised by large variations in node density. A new epidemic algorithm for information dissemination in highly dynamic and intermittently connected VANET is introduced. It is shown through realistic simulations in highway traffic that the proposed algorithm is capable of reliable and efficient information dissemination in VANET in the face of frequent network fragmentation and large density variations.     

Dynamic spectrum access — concepts and future architectures

New trends and developments in radio technology are enhancing the future capabilities of devices to access electromagnetic spectrum using the full range of dimensions associated with the spectrum. This increased capability, together with current developments towards liberalisation of spectrum management regulations, are opening up opportunities to exploit an emerging paradigm in wireless communications and networking known as dynamic spectrum access (DSA). The key characteristic of DSA networks is their ability to exploit knowledge of their electromagnetic environment to adapt their operation and access to spectrum. Their key promise is that they open the possibility of highly efficient (re)use of spectrum. This paper introduces the main concepts behind DSA, reviews the proposed architectures for future DSA systems, and outlines some of the key research challenges associated with this new paradigm. Particular emphasis will be given to autonomous cognitive radio DSA.     

Reliable multicast for the Grid: a case study in experimental computer science

In its simplest form, multicast communication is the process of sending data packets from a source to multiple destinations in the same logical multicast group. IP multicast allows the efficient transport of data through wide-area networks, and its potentially great value for the Grid has been highlighted recently by a number of research groups. In this paper, we focus on the use of IP multicast in Grid applications, which require high-throughput reliable multicast. These include Grid-enabled computational steering and collaborative visualization applications, and wide-area distributed computing. We describe the results of our extensive evaluation studies of state-of-the-art reliable-multicast protocols, which were performed on the UK's high-speed academic networks. Based on these studies, we examine the ability of current reliable multicast technology to meet the Grid's requirements and discuss future directions.