臺灣大學: 電信工程學研究所陳光禎歐永俊Ao, Weng-ChonWeng-ChonAo2013-03-272018-07-052013-03-272018-07-052010http://ntur.lib.ntu.edu.tw//handle/246246/253167隨著無線通訊技術的發展及多媒體網路服務內容品質與需求的提升,感知無線電(cognitive radio)成為近年來其中一個熱門的研究方向。感知無線電具有頻譜偵測(spectrum sensing)技術來判斷目前的頻譜使用情況,以此動態調整傳輸參數設定。其中一種網路型態為由配置感知無線電的使用者共同構成一個次要網路(secondary/unlicensed network);該次要網路的使用者會主動偵測主要網路(primary/licensed network)的使用情況,以利用主要網路沒有充分使用的頻帶來傳輸,且同時限制對主要網路的使用者所帶來的額外干擾(interference)。本論文的目的是建立一個架構以分析次要網路與主要網路共存時,次要網路的拓撲(topology)、連接(connectivity)、傳輸延遲(latency)與干擾之間的關係。顯然地,次要網路與主要網路的不對等關係,導致次要網路的使用者要主動調整其傳送密度(density of active transmissions)以限制對主要使用者的干擾,維持其接收訊號的品質(QoS)。另一方面,由於主要使用者不用理會次要使用者的傳輸情形,所以次要使用者若要維持接收訊號的品質,其傳輸範圍(transmission range)會下降。在該架構之下,次要網路可以看作由其傳送密度及其傳送範圍構成的相變圖(phase diagram)中的一工作點(operating point),該工作點的位置會決定該網路的連接情形;次要網路的工作點在主要網路出現前後會變化,即其傳送密度及範圍皆下降致使連接崩解(可類比為物理系統中發生相變)。結合了滲透理論(Percolation theory)與隨機幾何(Stochastic geometry)的分析工具,可得到相變圖中工作點變化前後位置,從而進一步分析因傳送功率改變而描繪的軌跡,及得到因相變所導致的額外傳送延遲等。另外,本架構也進一步應用到不同的網路設計與協定分析,其中包括路由(routing)、合作傳送(cooperation)、資料散播(data dissemination)等。Characterizing the topology and therefore fundamental limit is a must to establish effective cognitive radio networking (CRN). However, there lacks complete understanding of the relationship among connectivity, interference, latency and other system parameters of the underlay CRN. To clarify this complication, by employing tools from both percolation theory and stochastic geometry, we provide a novel parametrization of underlay secondary ad hoc CRN wherein the secondary network is regarded as an operating point in the phase space in both cases with and without outage constraints on secondary links. Coexisting with a primary ad hoc network, the secondary network undergoes a phase transition due to avoiding interference to primary receivers, while being interfered by primary transmitters. Furthermore, transmit power allocation of secondary users is represented by a Pareto contour in the phase space, and the impact of interference on connectivity is captured by the latency-to-percolate. Based on this proposed framework, we develop and analyze many applications on underlay secondary network, such as benefits of importing avoidance regions, self-motivated cooperation scheme, delay minimizing routing, and data dissemination with epidemic broadcasting so that CRNs can successfully operate.745316 bytesapplication/pdfen-US感知無線電網路重疊式連接干擾路由資料散播cognitive radio networksunderlayconnectivityinterferenceroutingbroadcasting重疊式異質感知無線電網路之相變分析及其應用Phase Transition Analysis for Underlay Heterogeneous Cognitive Radio Networks with Applicationsthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/253167/1/ntu-99-R97942044-1.pdf