1,246 research outputs found
Dynamic Spectrum Allocation and Sharing in Cognitive Cooperative Networks
The dramatic increase of service quality and channel capacity in
wireless networks is severely limited by the scarcity of energy
and bandwidth, which are the two fundamental resources for
communications. New communications and networking paradigms such
as cooperative communication and cognitive radio networks emerged
in recent years that can intelligently and efficiently utilize
these scarce resources. With the development of these new
techniques, how to design efficient spectrum allocation and
sharing schemes becomes very important, due to the challenges
brought by the new techniques. In this dissertation we have
investigated several critical issues in spectrum allocation and
sharing and address these challenges.
Due to limited network resources in a multiuser radio environment,
a particular user may try to exploit the resources for
self-enrichment, which in turn may prompt other users to behave
the same way. In addition, cognitive users are able to make
intelligent decisions on spectrum usage and communication
parameters based on the sensed spectrum dynamics and other users'
decisions. Thus, it is important to analyze the intelligent
behavior and complicated interactions of cognitive users via
game-theoretic approaches. Moreover, the radio environment is
highly dynamic, subject to shadowing/fading, user mobility in
space/frequency domains, traffic variations, and etc. Such
dynamics brings a lot of overhead when users try to optimize
system performance through information exchange in real-time.
Hence, statistical modeling of spectrum variations becomes
essential in order to achieve near-optimal solutions on average.
In this dissertation, we first study a stochastic modeling
approach for dynamic spectrum access. Since the radio spectrum
environment is highly dynamic, we model the traffic variations in
dynamic spectrum access using continuous-time Markov chains that
characterizes future traffic patterns, and optimize access
probabilities to reduce performance degradation due to co-channel
interference. Second, we propose an evolutionary game framework
for cooperative spectrum sensing with selfish users, and develop
the optimal collaboration strategy that has better performance
than fully cooperating strategy. Further, we study user
cooperation enforcement for cooperative networks with selfish
users. We model the optimal relay selection and power control
problem as a Stackelberg game, and consider the joint benefits of
source nodes as buyers and relay nodes as sellers. The proposed
scheme achieves the same performance compared to traditional
centralized optimization while reducing the signaling overhead.
Finally, we investigate possible attacks on cooperative spectrum
sensing under the evolutionary sensing game framework, and analyze
their damage both theoretically and by simulations
Applications of Repeated Games in Wireless Networks: A Survey
A repeated game is an effective tool to model interactions and conflicts for
players aiming to achieve their objectives in a long-term basis. Contrary to
static noncooperative games that model an interaction among players in only one
period, in repeated games, interactions of players repeat for multiple periods;
and thus the players become aware of other players' past behaviors and their
future benefits, and will adapt their behavior accordingly. In wireless
networks, conflicts among wireless nodes can lead to selfish behaviors,
resulting in poor network performances and detrimental individual payoffs. In
this paper, we survey the applications of repeated games in different wireless
networks. The main goal is to demonstrate the use of repeated games to
encourage wireless nodes to cooperate, thereby improving network performances
and avoiding network disruption due to selfish behaviors. Furthermore, various
problems in wireless networks and variations of repeated game models together
with the corresponding solutions are discussed in this survey. Finally, we
outline some open issues and future research directions.Comment: 32 pages, 15 figures, 5 tables, 168 reference
Distributed Game Theoretic Optimization and Management of Multichannel ALOHA Networks
The problem of distributed rate maximization in multi-channel ALOHA networks
is considered. First, we study the problem of constrained distributed rate
maximization, where user rates are subject to total transmission probability
constraints. We propose a best-response algorithm, where each user updates its
strategy to increase its rate according to the channel state information and
the current channel utilization. We prove the convergence of the algorithm to a
Nash equilibrium in both homogeneous and heterogeneous networks using the
theory of potential games. The performance of the best-response dynamic is
analyzed and compared to a simple transmission scheme, where users transmit
over the channel with the highest collision-free utility. Then, we consider the
case where users are not restricted by transmission probability constraints.
Distributed rate maximization under uncertainty is considered to achieve both
efficiency and fairness among users. We propose a distributed scheme where
users adjust their transmission probability to maximize their rates according
to the current network state, while maintaining the desired load on the
channels. We show that our approach plays an important role in achieving the
Nash bargaining solution among users. Sequential and parallel algorithms are
proposed to achieve the target solution in a distributed manner. The
efficiencies of the algorithms are demonstrated through both theoretical and
simulation results.Comment: 34 pages, 6 figures, accepted for publication in the IEEE/ACM
Transactions on Networking, part of this work was presented at IEEE CAMSAP
201
A Comprehensive Survey of Potential Game Approaches to Wireless Networks
Potential games form a class of non-cooperative games where unilateral
improvement dynamics are guaranteed to converge in many practical cases. The
potential game approach has been applied to a wide range of wireless network
problems, particularly to a variety of channel assignment problems. In this
paper, the properties of potential games are introduced, and games in wireless
networks that have been proven to be potential games are comprehensively
discussed.Comment: 44 pages, 6 figures, to appear in IEICE Transactions on
Communications, vol. E98-B, no. 9, Sept. 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 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
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