Dynamic Resource Access Algorithms in Cognitive Radio Networks by Game Theory

Louni, Alireza | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41893 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Hossein Khalaj, Babak
  7. Abstract:
  8. Analysis of traditional spectrum allocation schemes shows underutilization of radio spectrum. This is main motivation behind deployment of cognitive radios and improving spectrum efficiency. One of the most important issues in cognitive radio networks is to guarantee quality of service (QoS) constraints for the primary users. Another problem which must be considered during network design is to design distributed algorithm with few amount of control messages. However, there is a tradeoff between to be distributed of algorithm and to be efficient. We have used game theory to analyze convergence, effectiveness and uniqueness of stable point of network.
    This thesis is organized in two parts. In the first part, a relay-based cognitive radio network is considered in which secondary users compete in a selfish manner to use a relay in order to improve their utility function, while maintaining interference at the primary receiver to be lower than a certain threshold level. This problem is modeled as a non-cooperative game and by using a proper cost function in the definition of the utility function; it is shown that despite the selfish behavior of the users, Nash equilibrium (NE) with sub-optimum property is achieved. A distributed and practical algorithm is also proposed. Furthermore, performance of the proposed algorithm in terms of various systems parameters is studied through simulations.
    During the last part, to improve quality of service of secondary users, a network of relays is considered to make beamforming. We have proved that the utility function has interesting properties in the terms of game theory parameters. Our simulation demonstrates great improvements of quality of service for secondary users. Finally, the problem of joint frequency and power allocation is modeled and solved
  9. Keywords:
  10. Game Theory ; Distributed Algorithm ; Service Quality ; Beamforming ; Cognitive Radio

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