等比例速率限制下多用戶多輸入多輸出正交分頻多工系統適應性資源分配

Abstract

次世代室內無線網路採用多用戶多輸入多輸出正交分頻多工系統以達到更佳的資 料傳輸速率。在室內環境中，使用者的通道可視為在一段相當長的時間內不會改變。因此，我們可根據各用戶的通道條件，將用戶適應性的分配到不同次載波上。除了最大化整體系統通道容量，我們把等比例速率限制條件列入考慮。在這篇論文中，我們利用等比例速率限制條件確保各用戶可達到其需求速率。文獻[12] 以分析的方法解決在多用戶正交分頻多工系統之資源分配最佳化問題。然而，因為假設在某些狀況下不成立的緣故，該方法無法直接套用到多用戶多輸入多輸出正交分頻多工系統。因此，我們提出較低運算複雜度，並可應用在多用戶多輸入多輸出正交分頻多工系統中，用戶分配演算法及能量分配演算法。模擬結果顯示，在最小用戶容量表現上，我們提出的演算法較修正過後的文獻[12] 演算法為佳。除此之外，我們也提出一個演算法，可將所提出的演算法應用在考量二元相位鍵移調變與四相位振幅調變的實際系統上。

In the next-generation wireless local area networks, techniques of multiuser multiple-input multiple-output orthogonal frequency division multiplexing(MU-MIMO OFDM) are adopted to achieve higher data rates. Since the channel condition can be treated unchanged for a very long period, Users and power can be allocated to subcarriers adaptively according to their channel conditions. Besides maximizing the system capacity, we take proportional rate constraint(PRC) into consideration. In this thesis, PRC is imposed to ensure that each user can achieve a required data rate, as in a system with quality of service guarantees. [12] solved the optimization problem analytically in MU-OFDM systems. However, it cannot be applied directly to MU-MIMO OFDM systems due to violation in assumptions. Hence, we propose a user selection algorithm and heuristic power allocation with a relatively low computation complexity for MU-MIMO OFDM systems with PRC. Our simulation shows that the proposed algorithm outperforms the modified algorithm of [12] in minimum user capacity. In addition, we propose an algorithm to fit our algorithms to real systems considering BPSK and QAM modulations. Furthermore, the sum rates among all users are distributed according to PRC.