第三代合作夥伴(3rd Generation Partnership Project, 3GPP)在5G行動通訊網路中提出增強型行動寬頻通訊(Enhanced Mobile Broadband, eMBB)的應用。在eMBB的應用中，使用者設備(User Equipment, UE)透過5G行動通訊網路觀看影音串流時可能會移動到訊號品質不好的地方，訊號品質不好會造成傳送的位元出錯，使得影音串流的封包被丟棄，大量被丟棄的封包會造成UE的播放畫面出現馬賽克或停格，因為使用大的網路頻寬卻傳送大量被丟棄的封包，這樣會導致5G行動通訊網路頻寬的浪費，為了解決網路頻寬浪費的問題，本論文在5G行動通訊網路中提出並實作一個動態調整影音串流的機制，Streaming Server會先在緩衝器中將上傳的影音串流轉碼成高、中、低三種影音品質，接著UE會週期性的將Data Rates與區塊錯誤率(Block Error Rate, BLER)回報給Streaming Server，Streaming Server再根據UE回報的Data Rate與BLER來選擇一種最適當的影音串流品質。我們在中山大學5G校園實驗網路實作本論文機制，為了驗證本論文機制可以根據訊號品質來動態調整影音串流，我們讓使用者從訊號品質好的地方移動到訊號品質差的地方，從實驗結果中，我們證實本論文所提出的動態調整影音串流機制可以大量減少封包遺失率與有效節省網路頻寬。

The 3rd Generation Partnership Project (3GPP) proposed Enhanced Mobile Broadband (eMBB) in the 5G mobile communication networks. In eMBB, when a user equipment (UE) is watching a video stream through 5G networks, he may move to a place where the signal quality is low. The poor signal quality causes serious bit errors during video transmission, which consequently produces packet losses. A large number of packet losses will cause frame in mosaics and/or frame freezes in the playback. Using large network bandwidth to deliver packets with large bit errors is just a bandwidth waste. In order to solve the bandwidth-waste problem, this thesis proposes and implements a dynamic adjustment scheme for video streaming in the 5G mobile communication networks. Streaming server will transcode an uploaded video stream into three different video qualities, high, medium, and low. UE then periodically reports the receiving data rates and block error rates (BLER) to the streaming server. The streaming server selects the appropriate quality of transcoded video stream based on the reported data rates and BLER by the UE. We design and implement the mechanism on the NSYSU-5G campus experimental networks. To verify the proposed mechanism, a UE in the experiment purposely moves from a place with relatively good signal quality to a place with poor. From the experimental results, we validate that the dynamic video adjustment scheme can greatly reduce the packet loss ratio and effectively save the network bandwidth.

論文審定書 i
致謝 ii
摘要 iii
Abstract iv
目錄 v
圖目錄 vii
表目錄 ix
第一章 導論 1
1.1 研究動機 1
1.2 研究方法 2
1.3 章節介紹 3
第二章 行動通訊網路的影音串流 4
2.1 5G行動通訊網路 4
2.1.1 NSA and SA 4
2.1.2 Open RAN 5
2.1.3 5GC 5
2.1.4 Block Error Rate 6
2.2影音串流 7
2.2.1 影音串流的轉碼 7
2.2.2 RTSP與RTP 10
2.2.3 影音串流的動態調整 10
2.2.4 影音串流的品質 12
2.3 相關研究 13
第三章　動態調整影音串流機制 15
3.1動態調整影音串流 15
3.2封包的排序與轉碼 18
3.3 DAVS系統模組 20
3.3.1 RDR量測模組 20
3.3.2 BLER量測模組 21
3.3.3 品質回報模組 22
3.3.4 SDR量測模組 23
3.4 DAVS演算法 25
第四章 實作與結果分析 29
4.1實驗環境與設備規格 29
4.2在UE上的實作 31
4.2.1 RDR量測模組的虛擬碼 31
4.2.2 BLER模組的虛擬碼 32
4.2.3 品質回報模組的虛擬碼 34
4.3在Streaming Server上的實作 35
4.3.1傳送緩衝區的新增 35
4.3.2 SDR量測模組的虛擬碼 36
4.3.2 DAVS演算法的虛擬碼 37
4.4實作的結果與分析 40
4.4.1實驗內容與參數設定 40
4.4.2結果分析 42
第五章 結論與未來工作 47
5.1 結論 47
5.2遭遇問題 48
Reference 49
Acronyms 53
Index 55

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