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http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/48651
標題: | 動態頻譜存取網路中整合式頻譜偵測及分享之媒體存取協定設計 An Integrated MAC Protocol Designed for Spectrum Sensing and Sharing in Dynamic Spectrum Access (DSA) Networks |
作者: | Tsung-Lin Li 李宗霖 |
指導教授: | 周俊廷(Chun-Ting Chou) |
關鍵字: | 媒體存取協定,動態頻譜存取,授權裝置,頻譜存取,偵測, DSA,primary device,secondary device,distributed,spectrum sensing,spectrum access, |
出版年 : | 2010 |
學位: | 碩士 |
摘要: | 現今的無線網路的頻譜使用是採用固定式頻譜分配,其最大的缺點便是頻譜的使用效率不佳,讓頻譜缺乏的問題日益嚴重。動態頻譜存取被視為在新一代無線網路中的一項關鍵技術。在動態頻譜存取的技術中,未授權裝置能動態地使用需授權頻段,只要這些未授權裝置的使用不影響原本的授權裝置的使用,如此可以提高整體頻譜的使用效率。然而,使用動態頻譜存取也面臨新的挑戰,一方面,未授權設備必須能找到足夠的閒置頻譜資源,達到應用層的要求。另一方面,未授權裝置在使用授權頻段時,不能干擾授權裝置原本的傳輸,也不能干擾到其他未授權裝置的使用。
在本論文中,我們提出了一個在動態頻譜存取網路中的整合式頻譜偵測及分享的演算法。這個演算法包含兩個部分:頻譜感測和頻譜存取協定。頻譜感測要求每個裝置在偵測頻譜時,兩次偵測的間隔必須是指數分佈。頻譜存取協定只允許最先發現一個閒置通道的未授權裝置,可以獨佔地使用此通道,直到有授權裝置又開始使用此通道。此演算法能夠將閒置的頻譜資源成比例地分配給未授權裝置,而且藉著調整偵測的速率,該裝置可有效地控制所獲得的頻譜資源。另外,我們發展了一套數學模型來分析和評估我們的演算法的效能,並且我們考慮了兩個重要參數---假報警的發生機率和偵測頻譜所需的時間---對此演算法的效能的影響。為了將此演算法實現於實際的網路環境中,我們設計了一個符合我們所提出的演算法的媒體存取協定,並且利用OPNET來模擬此協定。模擬所得到的結果驗證了我們提出的媒體存取協定,可以提供未授權裝置公平且有效率地使用頻譜資源。 Dynamic spectrum access (DSA) has been considered as a key technology for the next-generation wireless communications. In a DSA network, unlicensed devices can use the wireless spectrum opportunistically so as to improve the overall spectrum efficiency and application-level performance. However, allowing opportunistic use of wireless spectrum introduces new issues. On the one hand, devices must sense the spectrum to find enough spectrum resource and to reach the higher layer requirement. On the other hand, it is important for devices to access the channel without causing interference with licensed and unlicensed devices. In this thesis, we propose a new algorithm to provide secondary devices proportional sharing of available spectrum resource. The proposed algorithm includes a spectrum sensing mechanism and a spectrum access etiquette. The sensing mechanism requires every secondary device to scan the channel with exponentially-distributed scanning intervals. The access etiquette requires that the device which first finds an idle channel has the exclusive access to the channel until primary devices return to the channel. With the proposed algorithm, proportional sharing of the spectral resource among secondary devices can be achieved through simple control over their scanning rates. We develop a mathematical model and conduct numerical analysis to evaluate the effectiveness of our algorithm. Besides, two important parameters, the false-alarm probability and scanning overheads, are considered in our analysis. In order to implement our proposed algorithm in the real network, we also design a medium access control (MAC) protocol. Then, we simulate the proposed protocol using the OPNET Modeler. Our analysis and simulation results demonstrate that the protocol provides competing secondary devices proportional sharing of the spectrum resource, as suggested by the proposed algorithm, in a distributed manner. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/48651 |
全文授權: | 有償授權 |
顯示於系所單位: | 電信工程學研究所 |
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ntu-99-1.pdf 目前未授權公開取用 | 8.5 MB | Adobe PDF |
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