在異質與軟體定義網路整合環境下的存取網路搜尋與選擇功能之研究

Abstract

行動網路的流量隨著智慧型行動裝置的普及而快速成長，為了要因應快速成長的流量，異質網路整合被視為一個可行的解決方法。透過異質網路(如長期演進技術網路與Wi-Fi無線網路)覆蓋範圍的重疊，行動電信營運商可以使用卸載服務(如Wi-Fi網路卸載)來減少網路壅塞。因此，需要一個合適的網路協調機制來達到Wi-Fi網路的負載平衡。在本論文中，我們使用存取網路搜尋與選擇功能來建議使用者裝置存取合適的基地台(如長期演進技術的演進節點B與Wi-Fi網路基地台)以達到負載平衡。我們整合存取網路搜尋與選擇功能和體定義網路來讓此整合式網路具備可程式化，彈性與可動態管理的特性。此外我們也提供一個省電的演算法來適當地配置網路資源給使用者裝置，以節省Wi-Fi網路基地台的電力。經由所提之模擬模型與效能評估結果顯示，當網路流量不平衡的時後，我們提出的演算法與以往的研究相比，能夠因應幾乎同樣數量的使用者裝置資源請求，且我們提出的演算法可以省下15.62%的Wi-Fi基地台電力。

The mobile traffic has grown rapidly with the popularity of smart mobile devices. To accommodate increasing traffic, heterogeneous network integration is considered as a viable solution. Through the overlapping coverage of heterogeneous networks (e.g., LTE and Wi-Fi), the mobile operators can use the offloading service (e.g., Wi-Fi offloading) to reduce network congestion. Thus a proper network coordination mechanism is required for load balancing of the Wi-Fi network. In this thesis, we use Access Network Discovery and Selection Function (ANDSF) to suggest proper base stations (e.g., LTE evolved Node Bs; eNBs and Wi-Fi access points; APs) to user equipment (UE) for load balancing. We integrate the ANDSF with software-define networking (SDN) to make the ANDSF-aided integrated network more programmable, flexible and dynamically manageable. Moreover, we propose a Power-Saving ANDSF (PSA) algorithm to appropriately assign network resource to UEs and save the power of Wi-Fi APs. The simulation model and performance evaluation results show that the successful probability of UEs’ resource requests to PSA is almost the same as the proposed schemes of the previous studies when the network traffic is unbalanced. Our study indicates that PSA saves 15.62% more Wi-Fi AP’s power than the previous research in the unbalanced traffic network.