在LTE網路環境下，基於時間延遲與資料量緊急度之即時性流量排程設計

Real-Time Scheduling based on Delay and Rate Urgency in LTE

李仲哲(Chung-Che Li)

指導教授 ： 楊峻權

國立暨南國際大學/科技學院/資訊工程學系/碩士(2016年)

摘要

隨著科技發展日新月異，行動裝置的普及化，近年來人們對行動網路的需求也越來越大。長程演進技術(Long Term Evolution, LTE)提供了一種簡單、省時省力，並且成本較低的方式來進行部署4G網路基礎設施，是目前4G標準中被看好的一種無線網路接取技術，在LTE的環境架構之下，規範了行動用戶(User Equipment, UE)如何透過無線訊號與LTE核心網路(Evolved Packet Core, EPC)的基地台(Evolved NodeB, eNB)連線並進行無線通訊。
為了使多媒體服務和高頻寬數據的傳輸有更好的效率，LTE在MAC層中，還具有了Quality of Service (QoS)的概念，並依照不同的資料流量種類分成不同的QoS等級。如何在有限的無線資源條件下，達到最有效的無線資源分配，並且可以在QoS、公平性及吞吐量之間取得最好的平衡，使得每一個UE透過無線網路傳輸資料時，都可以有不錯的使用品質，一直都是無線資源排程研究的討論議題。在傳統的排程演算法中，大多數都只考慮到rate或delay其中單一因素，但是每一個UE之間實際所需的rate和delay可能有所不同，所以本文將依照各個UE之間的rate和delay需求不同，在同時考慮訊號品質的情況下，提出基於rate和delay緊急度的排程演算法，而最後的效能結果，會與其它也是考慮rate及delay因素的排程演算法比較，分別會觀察吞吐量、封包遺失率，以及本篇根據Jain’s Fairness Index所修改的吞吐量比例公平性與封包遺失率公平性，可以發現我們所提出來的兩種scheme，與對照組比較後，分別在系統吞吐量以及系統公平性上各有不錯的效果。

關鍵字

長程演進技術 ； 即時性資料流量 ； 公平性 ； 服務品質 ； 資源分配 ； 排程

並列摘要

Along with the rapid development of science and technology and the popularity of mobile devices, as a result, people's demand for mobile network is growing in recent years. The Long Term Evolution (LTE) provides a simple, time-saving, effort, and lower-cost method to deploy 4G network infrastructure. It is one of potential wireless network access technologies in the 4G standard. In the LTE, the specification defines how the User Equipment (UE) communicating with the Evolved NodeB (eNB) of Evolved Packet Core (EPC) via wireless signal.
In order to provide better transmission efficiency in multimedia services and high bandwidth data traffic, the LTE MAC protocol provides Quality of Service (QoS) that classifies different kinds of traffic flow into different QoS classes.
How to achieve the most effective scheduling of limited radio resources, achieve the best balance between the QoS, fairness and throughput, and let each UE transmitting data traffic over wireless network with well quality is one of MAC scheduling research issues. In traditional scheduling algorithm, only one single factor, "rate" or "delay," is considered. However, different UE may need different transmission rate and delay budget. Therefore, this thesis proposes two new scheduling schemes based on the urgency among rate and delay. The proposed schemes schedule UEs according to their rate and delay requirements while also consider the channel quality. The simulation compares the proposed scheme with other scheduling algorithms that are also involved with the rate and delay factors. The performance criteria will focus on throughput, packet loss ratio (PLR), as well as modified Jain's Fairness Index of throughput ratio fairness and PLR fairness. The simulation results show that the proposed two schemes will achieve a better performance compared with other scheduling schemes.

並列關鍵字

LTE ； Real-Time Traffic ； Fairness ； Quality of Service ； Resource Allocation ； Scheduling

參考文獻

[1] S. Sesia, I. Toufik, and M. P. J. Baker, LTE – The UMTS Long Term Evolution: From Theory to Practice, Wiley, Apr. 2009.

[2] 3GPP, “Radio Access Network; UTRAN Overall Description,” Tech. spec. TS 25.401, v. 10.2.0 (2011–06), 2011.

[3] 3GPP, “Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN),” Tech. spec. TS 36.300, v. 8.5.0, Mar. 2008.

[4] 3GPP, “Radio Access Network; E-UTRA and E-UTRAN Overall Description,” Tech. spec. TS 36.300, v. 11.1.0 (2012–03), 2012.

[5] S. Ali, M. Zeeshan, and A. Naveed, “A Capacity and Minimum Guarantee-based Service Class-Oriented Scheduler for LTE Networks,” EURASIP Journal on Wireless Communications and Networking, Mar. 2013.