臺灣博碩士論文加值系統

摘要- 隨著無線網路流量在許可頻譜的指數增長，移動網絡運營商打算使用免授權頻譜，如工業，科學和醫療（ISM）頻帶和卸載他們的交通量。在未來，首先關注在 5G 頻譜上，其中有兩個最突出的無線技術，長期演進（LTE）和 WiFi，將共同使用免授權頻譜。現有的實驗結果表明，LTE 在 5G 共存環境中受到 WiFI 的干擾影響較小，然而 WiFi 將會受到 LTE 嚴重的阻礙。為了實現公平的 LTE / WiFi 共存，我們提出了 CLW-LTE 共存方案，即 RTS 計數演算法。實驗結果表明，提出的 CLW-LTE 共存方案可以在 WiFi 和 LTE 之間提供公平的共存環境。
關鍵詞 - LTE-U、Wi-Fi、免執照頻段、流量估計、占空比

Abstract—With the exponential growth of wireless data traffic and the increasing scarcity of licensed spectrum, mobile network operators intend to use the unlicensed spectrum, such as the Industrial, Scientific and Medical (ISM) bands and TV white space, to offload their traffic. In the future, it is very likely that two of the most prominent wireless technologies, Long Term Evolution (LTE) and WiFi, will coexist on the same unlicensed bands. Exist-ing simulation results show that LTE is slightly impacted by such coexistence while WiFi is severely hampered by LTE transmissions. In order to realize a fair LTE/WiFi coexistence, we propose the CLW-LTE scheme for LTE in un-licensed bands, i.e., RTS Counting Algorithm. Simulation results show that the proposed CLW-LTE scheme schemes can provide a reasonable tradeoff between LTE and WiFi when they coexist with each other.
Index Terms - LTE-U、Wi-Fi、Unlicensed Spectrum、Traffic Counting、Duty Cycle

中文摘要i
Abstract ii
致謝iii
Contents iv
List of Figures vi
List of Tables vii
1 Introduction 1
2 Related work 4
2.1 LTE-U Coexistence Scheme . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1.1 Channel Sensing Based Design . . . . . . . . . . . . . . . . . . 5
2.1.2 A Proportional Fair Allocation . . . . . . . . . . . . . . . . . . . 5
2.2 Counting based Randomization . . . . . . . . . . . . . . . . . . . . . . . 6
2.2.1 Simple RFID Counting (SRC) . . . . . . . . . . . . . . . . . . . 6
2.2.2 The n1n2-Estimator . . . . . . . . . . . . . . . . . . . . . . . . 6
3 Preliminary 8
3.1 Challenges to LTE-WIFI Coexistence . . . . . . . . . . . . . . . . . . . 8
3.2 Environment Description . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.3 Problem Statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
4 The proposed coexistence scheme 13
4.1 Main Idea . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4.2 WiFi Traffic Volume . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.2.1 CLW-LTE:RTS Counting Algorithm . . . . . . . . . . . . . . . . 15
4.3 Duty Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.3.1 The proposed CLW-LTE algorithm . . . . . . . . . . . . . . . . 17
5 Performance anslysis 18
5.1 Monitoring cycle length . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
5.2 WiFi traffic volume without triggered RTS . . . . . . . . . . . . . . . . . 19
6 Simulation 20
6.1 Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.2 Accuracy of WiFi RTS counting . . . . . . . . . . . . . . . . . . . . . . 21
6.3 WiFi Throughput . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
6.4 LTE Throughput . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
6.5 Duty Cycle collision issue . . . . . . . . . . . . . . . . . . . . . . . . . 23
7 Conclusion 25
Bibliography 26

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