將未被主要使用者占據的頻段分配給次使用者使用以增加頻譜的使用率，即為感知無線電(Cognitive Radio)技術的目的。本文所討論的問題即在以正交分頻多工(OFDM)上行傳輸的感知無線電系統中，提出如何配置子載波與功率給次使用者以達最大傳輸率的方法。但此前提必須滿足次使用者傳輸功率與對主使用者干擾量的限制條件，且額外限制了每根子載波傳輸功率的上限。此篇論文研究提出一個兩階段的方法。在初始階段裡提出一參數用來決定分配子載波與功率給次使用者的順序，此參數是由功率與干擾量所組合而成。為了更進一步提高傳輸率，第二階段的方法被提出，應用於第一階段之後。此提出的兩階段方法與已發表方法的性能表現將在模擬的章節中做比較。提出的兩階段方法相較於已發表的方法有較好的性能表現。Cognitive radio (CR) technology is designed to enhance the frequency efficacy by allowing the secondary user to use the unoccupied frequency bands which belong to the primary user. A problem to maximize the transmission capacity of the secondary users subject to the power and mutual interference constraints in multiuser OFDM-based CR uplink systems is discussed in this thesis. A modulation order limitation on each subcarrier is also considered. The proposed two-phase scheme is designed based on the initial and iterative strategies. The initial allocation strategy is to assign subcarriers to users and allocate power to subcarriers by using a proposed indicator. The proposed indicator is composed of three portions which are related to the amount of power and interference. In order to further improve the performance, an iterative improvement approach is applied after the initial allocation strategy. In the simulation, the proposed allocation schemes outperform the existing schemes.
