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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/77443


    Title: 下行多載波多使用者利用多天線非正交多重接取技術之使用者分組以及資源配置演算法設計;User Grouping and Resource Allocation Algorithms for Multicarrier MIMO-NOMA Systems on Downlink Beamforming
    Authors: 曾睿弘;Tseng, Jui-Hung
    Contributors: 通訊工程學系
    Keywords: 非正交多重接取;正交多頻分工;調變模式;多載波;波束合成;non-orthogonal multiple access(NOMA);orthogonal frequency division multiple access;modulation mode;multicarrier;ZFBF
    Date: 2018-08-16
    Issue Date: 2018-08-31 14:38:49 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 本論文提出一個以正交分頻多工(OFDM)為基礎,結合非正交多重接取(NOMA)的系統,搭配使用者迭代選擇分組演算法、子載波配置演算法及位元配置演算法等資源配置的方式來降低整體系統的傳輸功率。在多天線非正交多重接取系統中,每一個子載波可以分配給一群由多組使用者組成的用戶們進行資料傳輸,而本論文以兩個使用者為一組,透過使用比正交分頻多工系統中單一使用者更低功率的調變方式進行資料傳輸以藉此降低傳輸所需的功率。然而也因為在多天線架構下同時進行傳輸,各組使用者亦會接收到來自其他天線所發送的資料干擾(Inter-group Interference);再者,由於多使用者共用同一段頻帶,即共享同一個子載波作資料傳輸,故會產生同頻帶之間的干擾(Co-channel Interference),而此些干擾類型也是多天線非正交分頻多重接取系統所主要需克服的難題。故為了因應上述干擾,論文中採用Zero-forcing Beamforming (ZFBF)以消除來自其他天線所傳出的干擾,同時搭配連續干擾消除技術(SIC)以消除來自傳輸功率較大的使用者之干擾。基於正交分頻多重接取的系統,主要使用者(Primary User)為原先傳輸的使用者,鑒於為了在進行非正交多重接取資源配置的時候保護原傳輸的主要使用者能仍保有於每一個被分配到的子載波中傳輸,次要使用者(Secondary User)會與主要使用者一起進行資料傳輸,但不會發生搶奪原先由單一主要傳輸者改為單一次要使用者進行資料傳輸的狀況。
    在本論文中將探討三個主要問題:一、各組用戶中的主要與次要使用者該如何自眾多使用者以挑選出表現最佳的使用者組合。二、在不同子載波的情況下,進行子載波配置問題。若當某個子載波中,只傳送給主要使用者所需的傳輸功率低於同時傳送至主要與次要使用者時,會選擇單獨傳送至主要使用者;反之,倘若傳送至主要與次要使用者所需的傳輸功率低於只傳送給主要使用者時,便會利用非正交多重接取技術以進行資料傳輸。最後,針對不同使用者與子載波的情況,進行調變技術的資源配置以決定最佳的整體系統所需的傳輸功率。
    本論文研究的非正交多重接取技術之資源配置設計,在模擬結果中顯示,當總傳輸功率維持一樣時,在某些情況下利用非正交多重接取進行資料傳輸能有效節省功率的輸出。;The non-orthogonal multiple access (NOMA) allocation becomes a promising technique on downlink transmission. Additionally, recent studies show that inter-group interference and inter-user inter-group play significant roles in minimizing the total required transmit power.
    In the multiple-input and multiple-output NOMA (MIMO-NOMA) systems based on orthogonal frequency division multiple access (OFDMA) systems with user grouping, subcarrier allocation and bit allocation schemes to reduce the required transmit power. Besides, we define each subcarrier is allocated to a cluster which contains groups of two users for data transmission with a lower power of modulation modes. The zero-forcing beamforming (ZFBF) and the successive interference cancellation (SIC) are used to eliminate interference from the strong user with the larger channel gain between two users in a group.
    Since the system is based on OFDMA systems, the primary user is more essential than the secondary and we ensure that all assigned subcarriers transmit data to the primary user. So the secondary user will transmit data with the primary user together on several subcarriers but it’s impossible to transmit data individually. Therefore, how to allocate the resource between the primary and secondary users under two conditions in the NOMA allocation will be discussed. Based on the simulation results, the proposed scheme outperforms the Multiple-User Orthogonal Multiple Access (MU-OMA) system with the NOMA allocation by decreasing the transmit power.
    Appears in Collections:[通訊工程研究所] 博碩士論文

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