Special Issue on European Wireless 2009 Conference

This European Transactions on Communication is a special issue devoted to the European Wireless 2009 Conference. The technical contributions, originally selected for their quality and significance, where extended and reviewed before being included in this journal. Cooperation in wireless networks, a highly explored research area in recent years, is here present basically in all included papers. Research communities from academia and industry have spent countless efforts in investigating and developing cooperative networking concepts, due to the high potential of such technology. Indeed, benefits include significant performance improvements at link, network and system level. Moreover, efficiency in resource utilisation can also be enhanced by these techniques. Quite often, cooperation and cognition are used together, as in the cases of cognitive radio and networking. The application area of cooperation and cognition is wide, and in this issue the focus is mostly on exploiting these principles in the lower layers of the OSI stack, particularly PHY and MAC layers. The included papers cover a variety of important and highly relevant research issues, including cognitive radio, relaying techniques, network coding, dynamic resource allocation techniques, and in general, cooperative techniques applied to multicarrier systems. The first paper on this issue discusses methodological aspects of spectrum occupancy evaluation in cognitive radios. Dynamic spectrum allocation for cellular networks is considered in the second paper. An approach is proposed to derive the optimal allocation policies in terms of operator reward following optimal, heuristic and Qlearning methodologies. The third paper on this issue studies soft frequency reuse and dynamic subcarrier assignments in cellular OFDMA networks. The performance of the soft frequency reuse technique is investigated as a function of the power profiles of the frequency reuse patterns. The fourth paper proposes the use of cooperative feedback in multiuser diversity systems to improve both capacity and error rate. The considered approach efficiently avoids resource allocation errors, resulting in improved link and network performance. The fifth paper investigates the use of network coding in wireless cooperative local clusters for filesharing applications. The sixth paper shows for the very first time a practical implementation of network coding on commercial mobile phones together with practical measurements on supported data rate and energy consumption. The seventh paper on this special issue deals with persistent resource allocations for VoIP traffic in packetswitching mobile cellular networks. This paper studies the problem of efficient transmission of VoIP in a packetswitched network with dominant data traffic. An opensource system level simulation platform for IMTAdvanced systems is presented on the eighth paper. The platform allows studying dynamic protocol behaviour in multicellular mobile radio network scenarios with detailed signal interference modelling. The ninth and last paper on this issue deals with exploiting relaying technology to improve data throughput and coverage inside a building. Editors would like to thank the authors of the publications for their hard work and support during the edition process. We are also indebted to the board, TPC and organising team of European Wireless 2009 for their continuous help and support. Finally, we would like to express our gratitude to the editorial team of Wiley for their kind assistance.