LTE與Wi-Fi整合技術(LTE-WLAN Aggregation, LWA)會在eNB中進行分流，將部分的封包透過AP傳送給一個UE，另外一部分的封包則透過eNB傳送給同一個UE，當eNB或AP其中任何一個發生網路壅塞情形時，如果使用固定比例的分流會導致UE的Throughput下降，為了解決上述的問題，本論文提出動態分流調整機制(Dynamic Stream Adjustment Scheme, DSAS)，此機制在eNB中新增封包遺失率(Packet Loss Ratio, PLR)計算模組與動態分流模組，在PLR計算模組中，eNB會將每個封包的傳送介面與PDCP (Packet Data Convergence Protocol) SN (Sequence Number)記錄在資料庫中，並透過UE定期回報給eNB的PDCP 狀態報告(PDCP Status Report, PSR)來計算LTE介面與Wi-Fi介面的PLR，在動態分流模組中，我們比較兩個介面的PLR，若Wi-Fi介面的PLR大於LTE介面的PLR，eNB會指數增加LTE介面的分流比例，反之，若LTE介面的PLR大於Wi-Fi介面的PLR，eNB會指數增加Wi-Fi介面的分流比例，最後我們使用ITRI LWA實作完成DSAS機制，從量測結果中我們驗證有使用本機制LWA UE 的Throughput會有效提高而且PLR會大幅下降。

LTE-WLAN Aggregation (LWA) can perform stream-splitting in eNB. In other words, partial packets are transmitted to one UE through AP, while partial packets are transmitted to the same UE through eNB. When network congestion occurs in eNB or AP, using a fixed ratio of stream-splitting will cause the throughput of UE to drop significantly. In order to resolve the above problem, this thesis proposes a dynamic stream adjustment scheme (DSAS). In DSAS, we design and implement two modules, a packet-loss-ratio (PLR) calculation module and a dynamic stream-splitting module, in eNB. In the PLR calculation module, eNB will record the transmission interface of each packet and the sequence number (SN) of packet data convergence protocol (PDCP) to the database. eNB then calculates the PLR of the LTE interface and the Wi-Fi interface, respectively, through the PDCP Status Report (PSR) periodically reported from a UE to eNB. In the dynamic stream-splitting module, we compare the PLR of the two interfaces. If the PLR of the Wi-Fi interface is greater than the PLR of the LTE interface, eNB will exponentially increase the stream-splitting ratio in the LTE interface. On the contrary, if the PLR of the LTE interface is greater than the PLR of the Wi-Fi interface, the eNB will exponentially increase the stream-splitting ratio of the Wi-Fi interface. Finally, we use the ITRI LWA platform to implement the proposed DSAS mechanism. From the experimental measurements, we validate that the system throughput of LWA by using the DSAS mechanism can be effectively improved and the PLR of both interfaces can drop significantly.

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 1
1.3 章節介紹 2
第二章 LWA的分流機制 3
2.1 Multi-RAT 3
2.2 Wi-Fi 4
2.3 LTE 6
2.3.1 RLC Header 7
2.3.2 PDCP Header 9
2.3.3 PDCP Status Report 10
2.4 LWA 14
2.5 相關研究 15
2.6 本論文機制 17
第三章 動態分流機制 18
3.1 動態分流系統架構 18
3.2 動態分流模組 20
3.3 PLR計算模組 24
3.4 Database 27
第四章 ITRI LWA平台的實作與結果分析 29
4.1 實驗環境與設備規格 29
4.2 在ITRI LWA平台上的實作 31
4.2.1 PLR計算模組 31
4.2.2動態分流模組 38
4.3實作結果與分析 44
4.3.1 實驗內容與參數設定 44
4.3.2 結果分析 45
第五章 結論與未來工作 51
5.1 結論 51
5.2 未來工作 52
Reference 53
Acronyms 57
Index 59

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