近年來，美國聯邦電信委員會(FCC)與電氣和電子工程師協會(IEEE)針對已規劃的頻譜過於擁擠的問題，展開了一連串的研究與討論。因此，提出了頻譜重複利用(spectrum reuse)的構想，並結合軟體無線電(software defined radio)的技術，定義出認知無線電 (cognitive radio)的技術。其目的在解決頻譜過於擁擠的問題，以頻譜再利用的概念，允許次使用者(secondary user)在主使用者(primary user)不使用的時間或頻率中，傳送無線信號於次使用者接收機。然而，於頻譜重複使用的優點下，亦同時伴隨著設計次使用者通信系統的挑戰。本子計畫將擬訂於三年期計畫，著手研究基於認知無線電的適應性傳輸技術，涵蓋適應性感知技術、適應性資源配置技術與適應性多天線傳輸技術。首先於認知無線電技術的IEEE802.22 WRAN 進行研究，進而發展各種適應性感知技術應用於資源配置演算法設計，以及研究各種多天線傳輸技術與時空碼，於感知無線電作出空間感知以及空間分集達到降低主使用者的干擾。結合感知技術，達到適應性多天線傳輸的資源配置技術，最後將之前研究之適應性資源配置技術，應用至各類無線網路架構集中管理式網路之WiMAX 系統以，及分散式管理系統如WLAN、超寬頻系統等等，並與其它子計畫做整合。本子計畫目標預計於第一年度建立IEEE 802.22 系統模擬平台，基於正交分頻多工技術的認知無線電系統適應性傳輸技術，以波形式感知技術完成適應性傳輸技術，並著手研究多天線傳輸技術，以波束合成為基礎的認知無線電系統的適應性資源配置。於第二年度預計完成以具有中繼站功能的合作式認知無線電系統網路，並利用以未知信號的能量感知技術，提出以人工智慧、基因演算法以及類神經網路的感知無線電之適應性傳輸演算法。此外，並延續第一年多天線傳輸技術，以多輸入輸出天線傳輸技術應用於多使用者之認知無線電網路資源配置問題。第三年度預計提出以集中式架構於感知無線電網路適應性演算法，與分散式網路架構之感知無線電網路適應性演算法，並將研究結果擴大應用於共存性的無線通信系統。 ; In recent years, due to over-crowed spectrum deployments, American Federal Communications Commission (FCC) and Institute of Electrical and Electronic Engineers (IEEE) had defined Cognitive Radio (CR) which utilizes a novel technology, Software Defined Radio (SDR), to sense the idle frequency bands and agilely employ the spectrum. Cognitive radio opens challenging problems in the scenario that secondary users sense and detect the spectrum hole in advance, then and build the spectrum maps to construct transmissions between secondary users. This project plans to have the period of three years focusing on adaptive transmission technologies, including adaptive resource allocation and multiple antenna technologies of cognitive radio. At first, we will focus on IEEE 802.22 WRAN which is first wireless technology based on cognitive radio. Adaptive sensing and resource allocation algorithms which are combined with multiple antenna technologies in views of cross layer design problem will be developed on the cognitive radio systems. In the end, we will put altogether the previous works and integrate the results with the other project results to develop complete cognitive radio technologies. Besides, the developed cognitive radio technologies will be employed on coexistence wireless networks. The goal of the first year is to buildup an IEEE 802.22 simulation platform with orthogonal frequency division multiplexing (OFDM) and beamforming technologies. During the second year, besides adaptive MIMO technologies under development, we will investigate a cooperative cognitive network which posses relay and broadcast channel deployment information. The artificial intelligence、gene based、or neural fuzzy algorithms of detection technologies will be proposed for the adaptive algorithms. Finally, centralized and distributed networks will be considered for building the platform to employ cognitive radio technologies to solve the coexistence issues. Moreover, the previous works will be investigated for the application to UWB and WiMAX systems to improve the system performances. ; 研究期間 9708 ~ 9807
