Game Theoretical Dynamic Spectrum Access in Cognitive Radios
Date Issued
2010
Date
2010
Author(s)
Lin, Yu-Yu
Abstract
Dynamic spectrum access (DSA) with the introduction of cognitive radio (CR) is considered as a promising technology in resolving the underutilization of current fixed spectrum assignment policy. Realistic dynamic spectrum access mechanism for cognitive radio networks (CRN) shall be distributed. CRs sense for spectrum opportunity and adaptively change the transmitting parameters to utilize the spectrum. One of the most critical issue in DSA is to resolve the competition among CRs and guarantee the QoS of licensed users. Due to the distributed and autonomous property of CRs, game theory provides a well-suited model in predicting the behavior of CR users, making it possible for us to design the system parameters accordingly to enforce CRs act at the desired operating region. In this thesis, we consider two issues in DSA from game theoretical point of view. In the first part, we deal with the channel selection problem in DSA. The limitation of sensing capability which result in partial spectrum knowledge is considered. The channel selection strategy is proposed basd on Nash equilibrium solution, which performs well even in large networks. In the second part, we practically consider the DSA in slotted primary system in presence of timing misalignment among primary system users and CRs. Timing misalignment introduce spectrum sensing error for CRs to detect primary system users and hence result in degradation in system throughput. Increase the sensing time that compensate the timing misalignment may be a straightforward solution. However, for selfish CR users, increased sensing time means larger vulnerable period in spectrum competition and degradation in CR throughput. We identify the optimal operating region of asynchronous DSA in which selfish CRs self-enforcingly protract the sensing time such that the primary user is protected and spectrum utilization is maximized. We show that under the properly chosen system parameter, system performance is assured even in presence of timing error.
Subjects
Game Theory
Cognitive Radio
Dynamic Spectrum Access
Timing Misalignment
Asynchronous
Channel Selection
Type
thesis
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