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UBC Theses and Dissertations

Coalitional game approach for cooperation strategy in cognitive radio networks Dai, Zhiyu

Abstract

Cognitive radio networks (CRNs) provide an effective solution to address the increasing demand for spectrum resources. The cooperation among secondary users (SUs) improves the sensing performance and spectrum efficiency. In this thesis, we study a traffic-demand based cooperative spectrum sensing and access strategy in a CRN with multiple SUs and multiple primary users (PUs). In the proposed strategy, each SU makes its own cooperation decision according to its traffic demand. When the SU has a high traffic demand, it selectively chooses channels to sense and access. When it has no data to transmit, it can choose not to perform sensing and save energy for future transmission. In the first part of the thesis, we study the traffic demand-based cooperation strategy in CRNs, in which each SU senses at most one channel during a time slot. We formulate this problem as a non-transferable utility (NTU) coalition formation game, in which each SU receives a coalition value that takes into account the expected throughput and energy efficiency. In order to obtain the final coalition structure, we propose a sequential coalition formation (SCF) algorithm. Simulation results show that our proposed algorithm achieves a higher throughput and energy efficiency than a previously proposed coalition formation algorithm in [1]. In the second part of this thesis, we extend the cooperation strategy problem in CRNs by enabling each SU to sense multiple channels during the sensing stage. We formulate the problem as an NTU overlapping coalitional game. We propose an overlapping coalition formation (OCF) algorithm to obtain a stable coalition structure. The proposed OCF algorithm is proved to converge after a finite number of iterations. We also modify the SCF algorithm proposed in the first part of this thesis to address the problem in the new system model. The modified SCF algorithm requires a lower number of iterations and involves less information exchange among SUs. Moreover, an adaptive transmission power control scheme is proposed for SUs to further improve their energy efficiency. Simulation results show that our proposed algorithms achieve a higher throughput than the disjoint coalition formation (DCF) algorithm.

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Attribution-NonCommercial-NoDerivs 2.5 Canada

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