In this thesis, we present two resource allocation schemes to exploit multiuser diversity gain for spatial multiuser communication systems so as to optimize the energy eciency.
Dierent users experience mutually independently fades on the subcarrier. Since the resource allocation problem is non-convex, the proposed schemes reformulate it to convex
with rate relaxation approach. Then the subcarriers are carefully assigned to users and power is redistributed based on minimum increase of power consumption to satisfy the minimum transmission data rate requirement of each user or maximum power reduction.
The proposed algorithms take the solution of multiuser multi-carrier system with rate relaxation (MMRR) problem as an initial point, which provides a lower bound due to the
relaxation and may be very close to the optimal solution, and this is why the performance can be greatly improved. One of the proposed algorithm is power reallocation over starvation and satiation algorithm (PRSS) classies users into two dierent groups based on the rate-distribution result of MMRR algorithm. One is called starvation group, and the other one is called satiation group. Any user in the starvation group can ask for the subcarrier which is not used or owned by the user in the satiation group by turns. The other algorithm is called ordered greedy power reallocation algorithm (OGPR). OGPR employs the subcarrier assignment of MMRR algorithm. Every user performs SUWF according to the subcarrier assignment to meet the minimum transmission data rate. Then, every user has the chance to ask other users for a subcarrier by turns based on the power consumption per user.
Both the proposed algorithms diminish the overall power consumption by reallocating one subcarrier to the user with maximum power reduction. The total transmission
power is minimized with xed bit-error-rate and constraint on each user's quality of service (QoS) requirement. Simulation results show that signicant power and diversity gain are achievable comparing with the conventional resource allocation approaches. The proposed schemes achieve the best energy eciency with relatively lower complexity and can be applied to 3GPP-LTE and WiMax (802.16e, 802.16m).

在資訊傳輸快速發展的時代，無線通訊系統已經廣泛地被人們使用來互通有無。其中，無線傳輸使用者迅速地增加以及可攜式通訊裝置因其功能受到電池的限制，使得能源損耗問題長久以來受到熱切的關注。在多使用者多頻帶的通訊系統下，本篇論文探討在維持一定傳輸品質下，如何妥善地利用通道的特性並將有限的資源(如功率、頻帶)有效率地分配以達到diversity 的發揮。因此，如何節省能源消耗成為本篇論文重要的研究方向。本篇論文中，我們提出兩種資源分配的方法，PRSS 和OGPS 演算法，在正交多頻分工調變(ODFM)通訊系統中，實現多使用者的diversity 並進一步地最佳化能源效益，而不同的使用者被假設在每一個不同頻帶經歷獨立的Rayleigh 訊號衰減。資源分配問題藉由傳輸速度條件的放寬而被重新列式成convex 的形。
在維持一定通訊品質(QoS)及錯誤率的情況下，所提出來的演算法根據此convex問題的最佳化結果重新分配頻帶和功率來滿足每個使用者最低傳輸速率的要求並達到最小的全部功率耗損。模擬結果顯示所提出的演算法與傳統資源分配方法比較後發現能夠更有效地利用diversity 來大幅地減少功率耗損，而當用戶數增加或可分配資源減少時，PRSS 和OGPR 演算法將更有效率地達到節能的目的。而所提出的方法在維持一定計算複雜度的情況下達到目前最佳的分配結果。其中，PRSS 演算法雖然需要比OGPR 演算法多耗費7%的能源，卻能使複雜度下降一半，如何在能源損耗和複雜度間取得平衡也將是未來值得探討的方向。

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