14,344 research outputs found
Band Allocation for Cognitive Radios with Buffered Primary and Secondary Users
In this paper, we study band allocation of buffered secondary
users (SUs) to orthogonal primary licensed bands, where each
primary band is assigned to one primary user (PU). Each SU is assigned to one
of the available primary bands with a certain probability designed to satisfy
some specified quality of service (QoS) requirements for the SUs. In the
proposed system, only one SU is assigned to a particular band. The optimization
problem used to obtain the stability region's envelope (closure) is shown to be
a linear program. We compare the stability region of the proposed system with
that of a system where each SU chooses a band randomly with some assignment
probability. We also compare with a fixed (deterministic) assignment system,
where only one SU is assigned to one of the primary bands all the time. We
prove the advantage of the proposed system over the other systems.Comment: Accepted in WCNC 201
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 distribuciĂł de les bandes de freqĂŒĂšncia de rĂ dio perquĂš el seu Ășs sigui mĂ©s efectiu. La tecnologia emergent que pot permetre aquest canvi de paradigma Ă©s la rĂ dio cognitiva. Han sorgit diferents models d'organitzaciĂł i gestiĂł de les rĂ dios cognitives, tots amb determinats fins estratĂšgics. En aquest article es revisen els patrons d'assignaciĂł de l'espectre de les xarxes de rĂ dio cognitiva i s'analitzen quals sĂłn la base comuna de cada model. S'exposen les vulnerabilitats i els desafiaments oberts que segueixen amenaçant l'adopciĂł i l'explotaciĂł de les rĂ dios cognitives per obrir les xarxes civils.La escasez de demandas de espectro hacen pensar en nuevas formas de gestionar la distribuciĂłn de las bandas de frecuencia de radio para que su uso sea mĂĄs efectivo. La tecnologĂa emergente que puede permitir este cambio de paradigma es la radio cognitiva. Han surgido diferentes modelos de organizaciĂłn y gestiĂłn de las radios cognitivas, todos con determinados fines estratĂ©gicos. En este artĂculo se revisan los patrones de asignaciĂłn del espectro de las redes de radio cognitiva y se analizan cuales son la base comĂșn de cada modelo. Se exponen las vulnerabilidades y los desafĂos abiertos que siguen amenazando la adopciĂłn y la explotaciĂłn de las radios cognitivas para abrir las redes civiles
Cognitive node selection and assignment algorithms for weighted cooperative sensing in radar systems
Cooperative Cognitive Relaying Under Primary and Secondary Quality of Service Satisfaction
This paper proposes a new cooperative protocol which involves cooperation
between primary and secondary users. We consider a cognitive setting with one
primary user and multiple secondary users. The time resource is partitioned
into discrete time slots. Each time slot, a secondary user is scheduled for
transmission according to time division multiple access, and the remainder of
the secondary users, which we refer to as secondary relays, attempt to decode
the primary packet. Afterwards, the secondary relays employ cooperative
beamforming to forward the primary packet and to provide protection to the
secondary destination of the secondary source scheduled for transmission from
interference. We characterize the diversity-multiplexing tradeoff of the
primary source under the proposed protocol. We consider certain quality of
service for each user specified by its required throughput. The optimization
problem is stated under such condition. It is shown that the optimization
problem is linear and can be readily solved. We show that the sum of the
secondary required throughputs must be less than or equal to the probability of
correct packets reception.Comment: This paper was accepted in PIMRC 201
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