單載波頻分多重存取環境之無妒忌子通道分配

近年來，隨著行動通訊技術的發展，手持裝置使用者的人數愈來愈多，所需的頻寬也愈來愈大，在有限的頻寬下，利用這些資源達到最大的傳輸量，是通訊研究的重點。但比較少研究探討使用者間的公平性問題，在日漸增多的行動通訊使用者趨勢下，這會是一個重要的課題。 3GPP LTE系統使用單載波頻分多重存取為上行技術，理由是單載波頻分多重存取為在正交頻分多重存取前加上離散傅立葉轉換預編碼，可以降低功率峰均值比，有效增加傳送功率。然而，在LTE上行規格裡，單載波頻分多重存取在子通道分配部分比正交頻分多重存取的自由度低很多，有著子通道分配方式的限制。所以在滿足這些限制下，如何有效的分配子通道而最小化使用者間頻譜效率，維持使用者間的公平性，是研究的核心。本文提出的無妒忌子通道分配方式，可以降低在單載波頻分多重存取環境下，用戶間因為子通道分配不均而產生的妒忌行為。演算法以最小化使用者彼此被分配到的頻譜效率差異總和為目標，達到最高的公平性。之後也提出如何在公平性與系統總體頻譜效率找出最佳權衡點，在維持一定的系統總體頻譜效率下，大幅改善使用者間的公平性問題。模擬結果顯示出，行人通道與車輛行駛通道分別可以保有至少80%以及75%的最大系統總體頻譜效率、且維持一樣好的SER表現前提下，與一般研究最大化系統總體頻譜效率的子通道分配方式比較，平均降低用戶間彼此的頻譜效率差異值約40倍，讓使用者不會因為子通道分配不均，頻譜效率有所差異而產生妒忌行為。

關鍵字

單載波頻分多重存取；子通道分配；無妒忌；公平性

並列摘要

Nowadays, thanks to the evolution of mobile communication, number of mobile equipment is increasing and bandwidth is also growing. Communication research want to find how to achieve maximum throughput in the limited bandwidth. But, fairness between users was talk about rarely in studies. It’s an important issue under the trend of increasing mobile communication users. 3GPP LTE uses single-carrier frequency division multiple access（SC-FDMA）architecture for the uplink. Unlike Orthogonal frequency division multiple access（OFDMA）, SC-FDMA add a pre-coder FFT. This method can reduce the peak to average power ratio, and effectively increase the transmission power efficiency. But, there are some restrictions of subchannel allocation in SC-FDMA. How to allocate the subchannels efficiently under the restrictions to maintain the fairness between users, is the kernel target in study. In this thesis, we proposed a subchannel allocation algorithm called ‟ envy-free suchannel allocation’’ which can reduce the envy behavior among users due to unequal allocated subchannel in SC-FDMA environments. The proposed scheme minimizes the total system spectral efficiency difference between each users. And then we proposed how to find the best tradeoff between fairness and total system spectral efficiency. It can improve fairness between users, subject to maintaining some total system spectral efficiency. Simulation results show that, by maintaining at least 80% and 75% total system spectral efficiency of ITU-R Ped.A channel and Veh.A channel, envy-free method can improve the spectral efficiency difference between users 40 times than general maximum total system spectral efficiency method in same SER performance. This envy-free subchannel allocation method significantly reduce the envy behavior among users.

並列關鍵字

SC-FDMA ； subchannel allocation ； envy-free ； fairness

參考文獻

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單載波頻分多重存取環境之無妒忌子通道分配

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