Increasing Spatial Spectrum Utilization Through Opportunistic User-to-User Communications

  • Dimitris Tsolkas
  • Nikos Passas
  • Lazaros Merakos


The requirements for ubiquitous and highly reliable wireless services, combined with the low utilization of licensed spectrum, call for flexible and efficient spectrum management schemes. To this end, a lot of attention is paid in the literature on allowing secondary-external users to opportunistically access the licensed spectrum. In parallel to these efforts, the question is whether the licensed users could further improve their own spectrum utilization. In this paper, we focus on increasing the spatial spectrum utilization of an infrastructure-based wireless system by adding autonomous functionality to the primary (system) users. An opportunistic operation mode for the uplink (UL) period, totally transparent to the base station (BS) of the system, is introduced. Users operating in this mode identify spatial spectrum UL opportunities by interpreting BS broadcast messages, and exploit these opportunities by establishing direct connections. It is shown that multiple direct connections can take place in parallel with a single standard UL transmission. Moreover, significant additional throughput is achieved, and in most of the cases, the energy consumption for the direct connections is lower than that of the conventional ones (using the standard mode).


Spatial spectrum reuse Uplink opportunities User-to-user communications Direct communications Opportunistic spectrum access 



This research has been co-financed by the European Union (European Social Fund—ESF) and Greek national funds through the Operational Program “Education and Lifelong Learning” of the National Strategic Reference Framework (NSRF)—Research Funding Program: “Heracleitus II—Investing in knowledge society through the European Social Fund”.


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Copyright information

© Springer Science+Business Media, LLC 2012

Authors and Affiliations

  • Dimitris Tsolkas
    • 1
  • Nikos Passas
    • 1
  • Lazaros Merakos
    • 1
  1. 1.Department of Informatics & TelecommunicationsUniversity of AthensAthensGreece

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