感知無線電(Cognitive Radio)技術是一個創新的無線電設計，主要目的是使用未被主使用者使用的頻段來增加頻譜使用的效率，避免造成浪費。正交分頻多工存取(OFDMA)被建議使用在感知無線電網路系統上。這篇論文我們最主要是討論在下行傳輸，在對主使用者干擾的限制條件下如何讓次使用者的通道容量最大。本論文將會提出兩個方法，與[6]中的方法以及傳統的方法做比較。模擬結果表現，我們提出的方法在有限的干擾下可以達到比其他方法更高的傳輸率。 Cognitive radio (CR) technology is an innovative radio design philosophy which aims to improve spectrum utilization by employing unused spectrum in dynamically changing environments. Orthogonal frequency division multiple access (OFDMA) has been suggested as a potential access scheme for CR systems.The downlink transmission capacity of the CR user is thereby maximized, while the interference introduced to the primary user (PU) remains under a specific threshold. We propose two schemes . The performance of proposed scheme is compared with the performance of classical schemes.Presented numerical results show that for a given interference threshold the proposed scheme allows the CR users to transmit more power in order to achieve higher transmission rate than the classical schemes.
