5G行動網路的三大應用包含增強型行動寬頻(enhanced Mobile Broadband, eMBB)、極高可靠低延遲通訊(Ultra-Reliable and Low-Latency Communications, URLLC)、大規模機器類型通訊(massive Machine-Type Communications, mMTC)，5G基地台(next Generation Node B, gNB)必須同時替三大應用的使用者設備(User Equipment, UE)轉傳封包，在有限資源區塊(Resource Blocks, RBs)的限制下，gNB除了要滿足URLLC應用對低延遲與高可靠率的要求外，也必須維持eMBB應用的資料傳輸率(Data Rate)並確保mMTC設備的成功連線。然而，目前的5G網路並沒有提供讓高優先權(例如URLLC)應用可以侵占(Preempt) eMBB或mMTC的應用，這會導致URLLC無法連線成功或增加排隊等待時間。為了解決上述問題，本論文提出一個具侵占式的資源分配(Preemptive Resource Allocations, PRA)演算法，在PRA機制中，gNB會讓讓三大應用封包分別進到三個不同的佇列(Queues)，當新的URLLC封包要進入佇列時，如果三個佇列皆已被封包佔滿，gNB會檢查佇列內是否有eMBB封包，如果有eMBB封包，即將進入佇列的URLLC封包就可以侵占已經在佇列內的eMBB封包，也就是說在佇列內的eMBB封包會被丟棄，如果佇列內沒有eMBB封包，則要進入佇列的URLLC封包就會被拒絕進入佇列，此外針對mMTC的應用，我們保證它有足夠的資源元素來做連線。為了分析PRA機制的效能，我們建立一個馬可夫鏈的數學模型，並根據馬可夫鏈狀態的穩定機率推導出網路效能參數，從數值分析結果中，我們證明PRA機制可以降低URLLC與mMTC的封包丟棄機率，因此可以達成URLLC低延遲的需求、維持eMBB的最小的資料傳輸率、確保mMTC的成功連線機率。

Three primary applications are defined in 5G mobile networks, which include enhanced Mobile Broadband (eMBB), Ultra-Reliable and Low-Latency Communications (URLLC), and massive Machine-Type Communications (mMTC). The next generation Node B (gNB) must simultaneously forward packets for User Equipment (UE) across the three applications. Given the limited availability of Resource Blocks (RBs), the gNB must not only meet the strict latency requirements of URLLC but also maintain the data rate demands of eMBB and ensure successful connectivity for mMTC devices. Current 5G networks lack a mechanism that allows higher-priority applications such as URLLC to preempt eMBB or mMTC traffic, which may result in URLLC connection failures or excessive queueing delay. To address this issue, we propose a preemptive resource allocation (PRA) mechanism. This mechanism first classifies packets from the three applications into separate queues. When a new URLLC packet arrives and all queues are full, the gNB checks for eMBB packets. If eMBB packets exist, the arriving URLLC packet is allowed to preempt one eMBB packet. If no eMBB packets exist, the incoming URLLC packet is denied admission. Additionally, the mechanism ensures that sufficient RBs are available to establish connectivity for mMTC traffic. To analyze the performance of the PRA mechanism, a Markov-chain model of the system is built, and performance metrics are obtained from the state probabilities. Based on the results of numerical analysis, we demonstrate that the PRA mechanism can reduce the packet drop probabilities of URLLC and mMTC. Additionally, the PRA can satisfy low-latency requirements of URLLC, maintain the minimum data rate for eMBB, and ensure successful connectivity for mMTC.

論文審定書...................................... i
致謝.................................................. ii
摘要.................................................. iii
Abstract............................................ iv
目錄.................................................. v
圖目錄.............................................. vii
表目錄.............................................. viii
第一章 導論..................................... 1
1.1 研究動機.................................... 1
1.2 研究方法.................................... 2
1.3 研究貢獻.................................... 3
1.4 章節介紹.................................... 3
第二章 5G網路的封包排程............ 4
2.1 5G OFDMA................................... 4
2.2 5G網路的三大應用.................... 7
2.3 排程演算法................................ 8
2.4 馬可夫鏈模型............................ 10
2.5 相關研究.................................... 11
第三章 5G侵占式的資源分配........ 15
3.1 系統架構.................................... 15
3.2 侵占式資源分配機制................ 16
3.3 馬可夫鏈數學模型.................... 17
3.3.1 模型假設................................. 17
3.3.2 狀態機率的計算..................... 21
3.3.3 效能參數的推導..................... 23
3.4 改變mMTC的Departure Rate.... 27
第四章 數值分析與結果討論......... 28
4.1 模型的參數設定........................ 28
4.2 數值結果與分析........................ 29
第五章 結論與未來工作................. 38
5.1 結論............................................ 38
5.2 本論文遭遇的困難.................... 39
5.3 未來工作.................................... 39
Reference......................................... 40
Acronyms......................................... 45
Index................................................. 47

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