隨著行動裝置的普及，全球資料傳輸流量快速的增加，現今的網路極度需要有效的行動數據分流解決方案。而在利用傳輸層進行分流的方法中，多重路徑TCP (MPTCP)可允許一份資料同時經由多條路徑進行傳輸，有利於資料傳輸效率的提升以及解決傳統移交程序進行時造成服務中斷的問題，為使用者提供具有更好的服務質量 (QoS) 和體驗質量 (QoE) 的服務。然而，現今核心網路中策略與計費控制系統 (PCC) 無法瞭解與實現多重路徑的運作方式，導致在分配核心網路頻寬時，總是依僅有核心網路的情況來進行頻寬分配，造成多數的頻寬資源浪費。
為了妥善運用傳輸層中多重路徑TCP的優點來進行行動數據分流，本篇論文提出相關的模型讓策略與計費控制系統能夠實現相關封包的偵測並得知當下可使用的路徑資源，制訂更好的規則。此外，我們也提出數學模型與程式模擬來計算與驗證行動裝置使用無線網路的時間，並進一步針對多重路徑TCP資料分流的流量、比率、服務質量和體驗質量進行分析，以協助策略與計費控制系統更妥善的分配與節省核心網路頻寬資源。

With the proliferation of mobile devices in recent years, the volume of global mobile data traffic has grown exponentially. As a result, effective methods for mobile data offloading are urgently required. A promising L4-approach known as Multipath TCP(MPTCP) has recently been proposed which allows a single transport connection to
use multiple paths simultaneously over multiple interfaces. In theory, the use of multipath
offloading overcomes the traditional barriers to the support of QoS and QoE over intermittently-connected WiFi networks. However, existing LTE Policy and Charging
Control (PCC) system is unaware of possible multipath connections. As a result, it determines the guaranteed bit-rate to the user as though no WiFi connections exist,
and hence the utilization efficiency of the cellular resources is seriously degraded. This thesis therefore proposes an L4 multipath offloading approach in which the LTE PCC system is rendered aware of alternative connection paths and allocates the available network resources accordingly. Moreover, an analytical model is proposed to assist the operator in evaluating the multipath offloading performance in terms of the offloading time, offloading volume, offloading ratio, and QoS/QoS satisfaction. The feasibility of the proposed approach is demonstrated by means of numerical simulations.

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