13,145 research outputs found
Spectrum sharing models in cognitive radio networks
Spectrum scarcity demands thinking new ways to
manage the distribution of radio frequency bands so that its use is more effective. The emerging technology that can enable this paradigm shift is the cognitive radio. Different models for
organizing and managing cognitive radios have emerged, all with specific strategic purposes. In this article we review the allocation spectrum patterns of cognitive radio networks and
analyse which are the common basis of each model.We expose the vulnerabilities and open challenges that still threaten the adoption
and exploitation of cognitive radios for open civil networks.L'escassetat de demandes d'espectre fan pensar en noves formes de gestionar la distribució de les bandes de freqüència de ràdio perquè el seu ús sigui més efectiu. La tecnologia emergent que pot permetre aquest canvi de paradigma és la ràdio cognitiva. Han sorgit diferents models d'organització i gestió de les ràdios cognitives, tots amb determinats fins estratègics. En aquest article es revisen els patrons d'assignació de l'espectre de les xarxes de ràdio cognitiva i s'analitzen quals són la base comuna de cada model. S'exposen les vulnerabilitats i els desafiaments oberts que segueixen amenaçant l'adopció i l'explotació de les ràdios cognitives per obrir les xarxes civils.La escasez de demandas de espectro hacen pensar en nuevas formas de gestionar la distribución de las bandas de frecuencia de radio para que su uso sea más efectivo. La tecnología emergente que puede permitir este cambio de paradigma es la radio cognitiva. Han surgido diferentes modelos de organización y gestión de las radios cognitivas, todos con determinados fines estratégicos. En este artículo se revisan los patrones de asignación del espectro de las redes de radio cognitiva y se analizan cuales son la base común de cada modelo. Se exponen las vulnerabilidades y los desafíos abiertos que siguen amenazando la adopción y la explotación de las radios cognitivas para abrir las redes civiles
Spectrum Coordination in Energy Efficient Cognitive Radio Networks
Device coordination in open spectrum systems is a challenging problem,
particularly since users experience varying spectrum availability over time and
location. In this paper, we propose a game theoretical approach that allows
cognitive radio pairs, namely the primary user (PU) and the secondary user
(SU), to update their transmission powers and frequencies simultaneously.
Specifically, we address a Stackelberg game model in which individual users
attempt to hierarchically access to the wireless spectrum while maximizing
their energy efficiency. A thorough analysis of the existence, uniqueness and
characterization of the Stackelberg equilibrium is conducted. In particular, we
show that a spectrum coordination naturally occurs when both actors in the
system decide sequentially about their powers and their transmitting carriers.
As a result, spectrum sensing in such a situation turns out to be a simple
detection of the presence/absence of a transmission on each sub-band. We also
show that when users experience very different channel gains on their two
carriers, they may choose to transmit on the same carrier at the Stackelberg
equilibrium as this contributes enough energy efficiency to outweigh the
interference degradation caused by the mutual transmission. Then, we provide an
algorithmic analysis on how the PU and the SU can reach such a spectrum
coordination using an appropriate learning process. We validate our results
through extensive simulations and compare the proposed algorithm to some
typical scenarios including the non-cooperative case and the
throughput-based-utility systems. Typically, it is shown that the proposed
Stackelberg decision approach optimizes the energy efficiency while still
maximizing the throughput at the equilibrium.Comment: 12 pages, 10 figures, to appear in IEEE Transactions on Vehicular
Technolog
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