為了支援4G電信通訊，第三代合作夥伴計畫(3rd Generation Partnership Project，簡稱為3GPP)組織持續的在發展長期演進技術(long term evolution，簡稱為LTE)；而在LTE的系統效能上，資料流排程(flow scheduling)扮演著很重要的角色，而根據flow的服務型態，主要可將其分類成GBR和non-GBR類型，然而，儘管已經有各種資料流排程的方法被提出，許多的方法並未將GBR flows從non-GBR flows中區分出來，使其無法提供GBR flows的服務品質(quality of service，簡稱為QoS) 需求。
因此，本論文設計了一種具服務差異化的下行資料流排程演算法 (service-differentiated downlink flow scheduling，簡稱為S-DFS)，其目標在滿足GBR flows的QoS需求並同時保證non-GBR flows的資料傳輸；首先，S-DFS演算法依據用戶設備(user equipment，簡稱為UE)之通道狀況將資源分配給UE，並根據LTE制訂的QoS分級指標(QoS class identifier，簡稱為QCI)讓flows之間擁有不同的優先權；接著，S-DFS演算法計算出一定數量的「可重新分配」資源並動態地將資源分配給有封包將要被丟棄的flows；實驗結果證明S-DFS演算法可以提升LTE網路的整體傳輸效率，此外，S-DFS演算法可以減少GBR封包的丟棄率(dropping ratio)和平均延遲(average delay)並同時增加non-GBR flows的吞吐量(throughput)。

The 3GPP organization continues developing long term evolution (LTE) to support the oncoming 4G cellular communication. In LTE, flow scheduling plays an important role in system performance, and flows are mainly categorized into guaranteed bit rate (GBR) and non-GBR classes depending on their service types. Although various flow scheduling schemes have been proposed, many of them do not differentiate GBR flows from non-GBR ones, which may not support quality of service (QoS) for GBR flows. Therefore, the paper designs a service-differentiated downlink flow scheduling (S-DFS) algorithm, whose objectives are to meet the QoS requirement of GBR flows, while guarantee the transmission of non-GBR flows. S-DFS starts by dealing out resource to user equipments based on their channel conditions, and prioritizes flows according to QoS class identifier (QCI) defined in LTE. Then, S-DFS calculates a dynamic amount of reallocatable resource, and adaptively gives such resource to those flows whose packets are about to be dropped. Experimental results demonstrate that S-DFS can improve the overall transmission efficiency of an LTE network. In addition, it can reduce both the dropping ratio and the average delay of GBR packets, while increases the data throughput of non-GBR flows.

論文審定書 i
致謝 ii
摘要 iii
Abstract iv
目錄 v
圖次 vi
表次 vii
第一章 導論 1
1.1 前言 1
1.1.1 無線存取技術與資源區塊 3
1.1.2 通道品質指標與服務品質分級指標 5
1.2 研究動機 10
1.3 論文貢獻與章節架構 11
第二章 相關背景與研究 12
2.1 問題定義與網路場景 12
2.2 相關文獻探討 13
第三章 S-DFS演算法 17
3.1 基礎資源排程 19
3.2 佇列裁減與預測 23
3.3 尋找「可重新分配」資源 24
3.4 資源重新分配 27
3.5 S-DFS演算法的設計原理 29
第四章 模擬結果與分析 31
4.1 Cell 的頻譜效率 33
4.2 Flows的資料吞吐量 35
4.3 GBR flows的封包丟棄率與封包延遲 40
4.4 α 與 β 參數之變動 45
第五章 結論與未來研究方向 53
參考文獻 54

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