View Item 
      •   Home
      • 7. Theses and Dissertations
      • Theses and Dissertations
      • View Item
      •   Home
      • 7. Theses and Dissertations
      • Theses and Dissertations
      • View Item
      JavaScript is disabled for your browser. Some features of this site may not work without it.
      Subject Lookup

      Browse

      All of DR-NTUCommunities & CollectionsTitlesAuthorsBy DateSubjectsThis CollectionTitlesAuthorsBy DateSubjects

      My Account

      Login

      Statistics

      Most Popular ItemsStatistics by CountryMost Popular Authors

      About DR-NTU

      Dynamic spectrum allocation using game theoretical approaches.

      Thumbnail
      View/Open
      La_Quang_Duy_G0802629A_PhD_Thesis.pdf (1.880Mb)
      Author
      La, Quang Duy.
      Date of Issue
      2013
      School
      School of Electrical and Electronic Engineering
      Abstract
      The increasing demand for spectrum due to the growing wireless services causes spectrum shortage and thus motivates changes in the way the spectrum resources are managed. With the limited spectrum available, mobile users will have to compete for frequency channels to transmit data. Such problems can be formulated as games where the players involved interact with one another, each with the objective of maximizing its own utility function selfishly. This thesis aims to adopt game theory in devising efficient radio resource management (RRM) algorithms for dynamic spectrum allocation in wireless communication systems. The RRM problem in this research is envisioned by using a two-tier framework. At the lower tier, the thesis considers games where players are the wireless devices, such as mobile users, access points, base stations, etc., which have data to transmit and need to access a common pool of the shared spectrum. For such systems, the underlying factor that may cause user performance degradation is co-channel interference (CCI). Consider a scenario with multiple transmitter-receiver pairs in an ad-hoc orthogonal frequency-division multiple access (OFDMA) network, where each pair of users needs to select OFDMA channels and a certain level of power to transmit in a distributed manner. In order to combat CCI, this problem is modeled as a strategic-form game with the utility function designed to optimize the signal-to-interference-and-noise (SINR) ratio. Iterative algorithms are devised to obtain the Nash equilibrium (NE), which is the stable operating point of the system. The iterative best-response techniques are frequently used in game theory but they might not guarantee convergence, especially when pure-strategy NEs might not exist. However, they do exist for certain classes of games, such as potential games. By adopting an interference-minimizing utility function, a potential game for the OFDMA system under investigation can be formulated. The results are further extended to an infrastructure-based multi-cell OFDMA network where a player consists of a base station and multiple mobile users in the cell. As such, pure-strategy NEs exist and can always be reached by using the best/better-response dynamics. Other issues such as the fairness among the center-users and edge-users in cellular OFDMA systems or the optimality analysis of the algorithms will also be addressed in this research. These methods are able to satisfy the users' target SINR and system fairness in the numerical simulation studies. At the upper tier, the thesis looks at a different scenario where the competition involves multiple licensed and unlicensed spectrum providers. The primary spectrum holders (PSHs) are the licensed spectrum users, e.g., operators in a geographical area, who are allowed to sell/lease portions of their available bandwidth to other unlicensed secondary service providers (SSPs) for monetary profits. Reallocating spectrum and encouraging sharing among the licensed and unlicensed service providers are new RRM methodologies proposed in future dynamic spectrum access systems, where micro-economic mechanisms could be employed to study the emerging spectrum market. This problem is viewed as an oligopolistic differential game between multiple PSHs, managed by a controller called the spectrum broker. By assuming the spectrum price is a dynamic continuous-time process governed by a differential equation, the proposed method seeks to find a Markov NE solution and determines the market equilibrium price. In addition, a discrete-time price adjustment which can be easily implemented at the spectrum broker is proposed. Extensive numerical studies are carried out to investigate the dynamic behaviors of the spectrum market.
      Subject
      DRNTU::Engineering::Electrical and electronic engineering::Wireless communication systems
      DRNTU::Science::Mathematics::Applied mathematics::Game theory
      Type
      Thesis
      Collections
      • Theses and Dissertations

      Show full item record


      NTU Library, Nanyang Avenue, Singapore 639798 © 2011 Nanyang Technological University. All rights reserved.
      DSpace software copyright © 2002-2015  DuraSpace
      Contact Us | Send Feedback
      Share |    
      Theme by 
      Atmire NV
       

       


      NTU Library, Nanyang Avenue, Singapore 639798 © 2011 Nanyang Technological University. All rights reserved.
      DSpace software copyright © 2002-2015  DuraSpace
      Contact Us | Send Feedback
      Share |    
      Theme by 
      Atmire NV
       

       

      DCSIMG