臺灣博碩士論文加值系統

IP flow mobility (IFOM) 使手機能夠分流自己的網路流量到不同的無限存取網路。基於此機制，由一個手機連上同一封包網路連線當中的所有的IP流量都可以藉由網路提供的路徑指示策略從3GPP服務下任意換至無線區域網路的服務下，反之亦然。然而，目前的路徑指示策略沒有訂定清楚：如何去分配多少IP流量以及到何處？進而導致下列四項主要問題：第一、IP流量可能被要求換到一個有很好訊號強度但後端壅塞的存取點（或是直接被防火牆禁止連線）。第二、要求IP流量嘗試去連上已經不堪負荷的存取點。第三、為了得知網路實際情況，而發出過多的網路訊號。第四、會降低正在連上被分流存取點上使用者的服務品質 (QoS) 。在這個研究中，我們為了解決上述的問題提出了兩個方案。其中，一個簡單一個較為複雜。在比例分流的方案中，我們提供了分配多少比例的流量要到目標分流點造成的影響。在比例與優先權的方案中，除了同樣提供分配比例的影響，同時也考慮目標分流點上面使用者的公平性。對於只能使用目標分流點的存取IP流量擁有較高的優先權。為了驗證提出的兩個方案，我們在詳細的分析模型上提出了大量的效能分析。此外我們的研究模型經由巨量的ns2模擬驗證了我們的方法藉由增加少量的訊號，卻可以提升大量的網路資源使用率。我們的研究提了手機供營運商一個理論上的指導方針，去規劃以及最佳化網路且不用廣泛的佈建與節省了時間和金錢。

IP Flow Mobility (IFOM) enables a UE to offload data traffic at IP flow level. Based on IFOM, IP flows within a packet data network (PDN) can be split to a cellular access network and a target access network by indication from routing policy. However, how to split the IP flows is not clear in the current routing policies, which may lead to the following problems: the IP flows (1) may be routed to a target access network having strong signal strength but with backhaul congestion (or just simply blocked by firewalls), (2) may exceed the capability of the target access network, (3) may cause lots of signaling overhead to realize the network condition, and (4) deteriorate the Quality of Service (QoS) of target access users. In this thesis, we propose two schemes, from simple one to a more complicated one, to solve the aforementioned problems. In Proportional Offloading (PO) scheme, we answer the question: how many percent of IP flows should be routed to the target access network. An optimal proportion can be calculated to route the IP flows. In the Proportional and Preempt-enabled Offloading (PPO) scheme, the fairness of users and network throughput is taken into consideration. The IP flows of target access users are granted higher priorities than the offloaded IP flows from the 3GPP access network. Moreover, the procedure for transferring IP flow can be the candidate solution for Network-based IFOM. Detailed analytical models are proposed to quantify the performance for the PO and the PPO. Moreover, we demonstrate, through extensive simulations by using ns2, that the PPO increases resource utilization significantly by only slightly compromising signaling overhead. Our study provides theoretical guidelines for mobile operators to plan and optimize their networks without wide deployment.

Abstract in Chinese I
Abstract II
Acknowledgement III
Contents IV
List of Figures V
List of Tables VI
1 Introduction 1
2 Background 6
2.1 IFOM 6
2.1.1 PDN Connection 7
2.1.2 Binding Cache 8
2.1.3 LTE Bearer Resource Control 9
2.1.4 Procedure of IFOM 9
2.2 Routing Policies on ANDSF 11
3 Proposed Schemes 13
3.1 Proportional Offloading (PO) Scheme 13
3.2 Proportional and Preemption-enabled Offloading (PPO) Scheme 14
4 Analytical Model 17
5 Numerical Results 35
6 Conclusions 42
Bibliography 43

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