未來5G核心網路移動管理組件的非存取層模組之實作

Abstract

隨著現今網路的快速發展，深入了生活中的每一部份，不僅一般手機使用者對其的要求如頻寬、可靠度等等的日漸提高，也開始出現各種不同類型使用者如高速交通工具、大量裝置等等的需求，且根據下世代移動網路聯盟 NGMN所提出的5G白皮書，其中有一項便是大量裝置的連線需求，便可看出對不同類型使用者提供相應服務的迫切，然而現今的 4G 核心網路，卻有著兩大根本上的限制，一為網路元件皆為使用專用硬體佈建而成，另一則是無法針對不同類型的使用者有專門的客製化服務。 本篇論文主要有兩大貢獻，一為透過個5G Core Network Testbed (Open5GCore)，修改其軟體的限制以及加入 Software Defined Networking (SDN) 之能力，實作了一套系統能透過 Network Function Virtualization (NFV) 有效的scale up / down 網路元件，且能根據不同類型的使用者，開啟相對應的專用核心網路，稱為Network Slice，且能依據使用者的流量，動態的開啟或關閉 Slice 的能力。而為了提供不同 Slice 專屬的網路服務，我們提出了一個模組化且可 reconfigurable 的核心網路概念，可以透過簡單的新增不同的模組，來產生出針對不同類型使用者，提供不同服務的核心網路元件。而本篇論文的另一貢獻則是實作了基礎核心網路元件之一的 Mobility Management Entity (MME) 之中的 Non-Access-Stratum (NAS) Protocol，此為MME之基礎網路服務，以此模組為基石，便可新增其他類型使用者專用服務之模組，來產生不同類型使用者專屬的MME。

Mobile phones are becoming a part of our daily life. Not only human users, but also other types of devices such as high-speed vehicles, massive machine-type users ask for more and more bandwidth and reliability of mobile networks. According to the 5G white paper proposed by Next Generation Mobile Network (NGMN), it requires to provide services to heterogeneous types of users including human users and massive machine-type users. Therefore, it is critical to provide optimized services to different types of users. However, today’s 4G core networks have two fundamental limits: the first one is that every network entity is built by dedicated hardware; another one is that the 4G core networks cannot provide customized services to different types of users. In this thesis, we first dealt with the restricts of a core network testbed, Open5GCore, and integrated it with Software Defined Networking (SDN) to build a system that can use Network Function Virtualization (NFV) to easily scale up/down network entities. Moreover, our system can open Network Slices according to the needs of different types of users. It can also dynamically open/close network slices according to user’s network flows. We then proposed a way to modularize, reconfigurable core networks. It can easily add new modules to create customized network entities. Another contribution of this thesis is that we have implemented the NAS protocol in MME. Developer can use this common MME to build different MMEs by adding different modules.