在感知網路中使用潛在賽局的動態頻譜分配

Abstract

近幾年感知無線電(Cognitive Radio, CR)被視為極具潛力的無線通訊應用。在本篇論文中，提出的演算法是基於賽局理論中的潛在賽局，並在感知無線電網路中使用調適性功率控制來解決網路吞吐量與使用者因過大傳輸功率造成的相互干擾問題。模擬的環境是分散式與合作式傳輸模型，由一個主要使用者與數個次要使用者使用Ad-Hoc模式在相同傳輸通道下組成。在演算法的架構下，沒有任何次要使用者會使用過大的傳輸功率來增加自己的SINR，演算法會驅使所有次要使用者收斂到奈許平衡點(Nash Equilibrium)。三個功率指標會在演算法中會被個別考慮到。第一個和主要使用者的SINR需求有關；第二個功率考慮到次要使用者的SINR需求；第三個功率指標從潛在賽局中所提出的效用函數得到。由於從效用函數中得到的最佳響應未必能實際應用在感知無線電的環境中，於是演算法流程明確地用特定限制條件分類來使用適合的功率指標，並改善在潛在賽局中的最佳收斂響應。因此，演算法提供次要使用者更健全的決策方法有效地使網路吞吐量增加與相互干擾的問題減少，而且使用者會選擇合適的傳輸功率，避免不必要的功率浪費。本論文提出的演算法能達到節省功率的效果，也適合應用在綠色通訊上與有效的動態頻譜分配改善頻譜使用情況。 關鍵字：感知無線電; 軟體定義無線電; 賽局理論; 潛在賽局; 功率控制; 綠色通訊

In recent years, Cognitive Radio(CR) is a potential application in wireless communications. The algorithm, which uses Potential Game, proposed in this thesis solving the throughput and mutual interference problems, caused by excess transmission power, with adaptive power control in Cognitive Radio networks. The simulation environment is distributive and cooperative transmission model, which is composed of a primary users and some secondary users on the same channel with Ad-Hoc mode. Under the algorithm architecture, no user would choose excess power to gain their own larger SINR. The algorithm would make all secondary users converge to Nash Equilibrium. In addition, three power levels is concerned. First, power from primary user’s SINR requirement. Second, secondary user’s SINR requirement power. Third, the power obtained from utility function in Potential Game. The algorithm flow clearly classify with specific constraints to choose suitable power levels and improve Best Response Convergence in Potential Game due to the best response in utility function is not always established in real Cognitive Radio environment. Therefore, the algorithm provides secondary users with more robust decision making to efficiently cope with increment of throughput and decrement of mutual interference. Secondary users would choose proper power level to avoid power waste. The algorithm in this thesis can facilitate power saving and is available for Green Communications and dynamic spectrum access(DSA) in efficient spectrum utilization. key words: Cognitive Radio; Software Defined Radio; Game Theory; Potential Game; Power Control; Green Communications