隨著第五代無線通訊對高資料傳輸率與大頻寬需求的提升，混合波束成形技術已成為實現大規模多輸入多輸出正交分頻多工系統中降低硬體成本與能源消耗的關鍵技術之一。另一方面，為了提升頻譜利用效率並滿足多使用者服務的需求，子載波分配技術逐漸受到重視，尤其在毫米波頻段中，子載波資源的管理將顯著影響系統整體的功率消耗與用戶服務品質。 本論文針對下行多使用者多輸入多輸出正交分頻多工混合波束成形系統提出一種結合子載波重用的子載波分配演算法，旨在滿足服務品質要求的前提下，例如每個用戶的資料傳輸率，最小化總系統傳送功率。我們設計的演算法考慮每個使用者在每根子載波上的通道狀況，並透過通道增益分配子載波給特定的用戶，以提高子載波重用效率。此外，為了驗證所提演算法的有效性，我們與數種現有子載波分配方法進行比較，包括無重用方式、隨機分配等，並在不同用戶數下進行模擬，分析其相對傳送功率差異。 模擬結果顯示，所提出之子載波分配演算法在多種情境下均能有效降低相對傳送功率，並在子載波重用方面展現出明顯優勢。整體而言，本研究證實結合子載波重用的分配方法在混合波束成形架構下，不僅具備降低總傳送功率的能力，亦能在實際通訊系統中兼顧效能與實作可行性。 ;With the increasing demand for high data rates and large bandwidth in fifth-generation (5G) wireless communication, hybrid beamforming has emerged as a key technology for reducing hardware cost and power consumption in massive MIMO-OFDM systems. Meanwhile, to improve spectral efficiency and meet the needs of multi-user services, subcarrier allocation techniques have gained significant attention. This is especially critical in the millimeter-wave band, where the management of subcarrier resources greatly impacts overall system power consumption and user quality of service. In this thesis, we propose a subcarrier allocation algorithm with subcarrier reuse for downlink multi-user MIMO-OFDM hybrid beamforming systems. The goal is to minimize the total transmit power of the system while satisfying quality-of-service (QoS) requirements, such as user data rate. The proposed algorithm takes into account the channel condition of each user on each subcarrier and allocates subcarriers based on channel gain to enhance reuse efficiency. To validate the effectiveness of the proposed scheme, comparisons are made with several existing subcarrier allocation schemes, including non-reuse and random allocation methods. Simulations are conducted under different numbers of users to evaluate the differences in relative transmit power. Simulation results demonstrate that the proposed algorithm effectively reduces the relative transmit power under various scenarios and achieves notable advantage in subcarrier reuse. Overall, this study confirms that integrating subcarrier reuse into allocation strategies within hybrid beamforming architecture not only reduces total transmit power but also offers a practical and efficient solution for real-world communication system.
