教育部補助「行動寬頻尖端技術跨校教學聯盟第二期計畫 -- 行動寬頻網路與應用 -- 小細胞基站聯盟中心」 EPC核心網路系統設計 課程單元 03：LTE-SAE 網路架構與元件 計畫主持人：許蒼嶺 (國立中山大學 電機工程學系) 授課教師：萬欽德 (國立高雄第一科技大學 電腦與通訊工程系)

System Architecture Evolution

LTE and SAE Long Term Evolution (LTE) refers to the Evolved UMTS Radio Access Network (E-UTRAN) System Architecture Evolution (SAE) refers to the Evolved Packet Core (EPC)

2G, 3G and 4G Network Architecture

All-IP Core, New Network Elements

LTE + EPC Elements & Interface

LTE Architecture &Terminologies EPC: Evolved Packet Core MME: Mobility Management Entity S-GW: Serving Gateway P-GW: Packet Data Network Gateway eUTRAN: Evolved UTRAN S1: Interface between EPC and eNB X2: Inter-eNB interface (logical Interface) SAE: System Architecture Evolution LTE: Long Term Evolution EPS: Evolved Packet System Ref. 3GPP TS 36.300

Architecture for 3GPP Accesses HSS: Home Subscriber Server PCRF: Policy & Charging Rule Function Ref. 3GPP TS 23.401

網路架構 LTE修改3G網路協定架構，使用封包為主網路，達到高傳輸速率及減少延遲 LTE架構分為E-UTRAN與核心網路EPC(Evolved Packet Core) 訊息傳輸分為Control-plane與User-plane區分網路控制封包及用戶傳輸資料封包

Evolved Packet Core (EPC) All-IP mobile core network From 3GPP Release: (Radio access): LTE  E-UTRAN (eNodeB) (Core network): SAE  EPC Evolved Packet System = E-UTRAN + EPC E-UTRAN EPC

Evolved Packet Core (EPC) New, all-IP mobile core network introduced with LTE End-to-end IP (All-IP) Clear delineation of control plane and data plane Simplified architecture: flat-IP architecture with a single core A multi-access core network based on the Internet Protocol (IP) EPC enables operators to deploy and operate one common packet core network for 3GPP radio access (LTE, 3G, and 2G) non-3GPP radio access (HRPD, WLAN, and WiMAX) fixed access (Ethernet, DSL, cable, and fiber).

Basic EPC Elements Mobility Management Entity (MME) Serving Gateway Control-plane element, responsible for high volume mobility management and connection management (up to thousands of eNodeBs) Serving Gateway Serving a large number of eNodeBs, focus on scalability and security Packet Data Network (PDN) Gateway IP management (“IP anchor”), connection to external data networks focus on highly scalable data connectivity and QoS enforcement Policy and Charging Rules Function (PCRF) Network-wide control of flows: detection, gating, QoS and flow- based charging, authorizes network-wide use of QoS resources (manages millions of service data flows)

核心網路 (EPC) 架構 行動管理實體(MME)、服務閘道(S-GW)及封包資料閘道 (PGW)、HSS(Home subscriber server)、Policy and Charging Rules Function(PCRF)、PSTN(Public Switched Telephone Network)

Function Split between E-UTRAN and EPC Ref. 3GPP TS 36.300

UE 使用者裝置User Equipment (UE) 一般使用者的手機稱之為使用者裝置 安裝SIM卡，取得電信服務

E-UTRAN 演進通用無線存取網路(Evolved Universal Terrestrial Radio Access Network，E-UTRAN) E-UTRAN包含基站(eNB)、UE及eNB之間透過無線介面LTE-Uu通訊。實際上LTE-Uu通訊協定堆疊(Protocol Stack)，按功能區分為三層 實體層PHY：傳遞無線電波訊號 媒體控制層MAC：實體層傳輸電波轉換成數位訊號 無線資源控制RRC(Radio Resource Control)和EPS(Evolved Packet System)：行動管理用戶資料IP封包

All radio access functions Functions at eNodeB All radio access functions Radio admission control Scheduling of UL and DL data Scheduling and transmission of paging and system broadcast IP header compression (PDCP) Outer-ARQ (RLC)

LTE網路元件介紹-PSTN EPC核心網路，LTE為降低複雜度在設計上採全IP架構，捨棄電話線路交換服務(PSTN)僅保留數據封包交換網路

MME 行動管理實體MME：核心網路實際管理UE的元件，處理控制訊號(Control)訊息 例如：移動性、身分認證及安全性等的管理

Functions of Mobility Management Entity (MME) Authentication Tracking area list management Idle mode UE reachability S-GW/PDN-GW selection Inter core network node signaling for mobility between 2G/3G and LTE Bearer management functions

MME Functionality NAS signaling; NAS signaling security; Inter CN node signaling for mobility between 3GPP access networks; Idle mode UE Reachability(including control and execution of paging retransmission); Tracking Area list management (for UE in idle and active mode); PDN GW and Serving GW selection; MME selection for handovers with MME change; SGSN selection for handovers to 2G or 3G 3GPP access networks; Roaming; Authentication; Bearer management functions including dedicated bearer establishment; Support for ETWS message transmission. Ref. 3GPP TS 23.401 One user can only be served by ONE MME.

S-GW 服務閘道S-GW：主要功能是傳遞用戶資料，也是LTE與其他系統間(2G、3G)相容切換 例如：尋找路由或是轉送資料封包、處理eNB間的換手(Handover)等

Functions of Serving Gateway (S-GW) Local mobility anchor for inter- eNB handovers Mobility anchoring for inter- 3GPP handovers Idle mode DL packet buffering Lawful interception Packet routing and forwarding

S-GW Functionality The local Mobility Anchor point for inter-eNB handover; Mobility anchoring for inter-3GPP mobility; E-UTRAN idle mode downlink packet buffering and initiation of network triggered service request procedure; Lawful Interception; Packet routing and forwarding; Transport level packet marking in the uplink and the downlink; Accounting on user and QCI granularity for inter-operator charging; UL and DL charging per UE, PDN, and QCI. One user can only be served by ONES-GW but more than one P-GW. Ref. 3GPP TS 23.401

P-GW 封包資料網路閘道P-GW：負責將用戶資料網PDN傳送，一般的網際網路或是其他專屬的封包網路。也做LTE與非3GPP系統(WLAN、WiMAX)相容切換 負責監控每一個流量，方便核網對網路流量做品質控管(QoS)及付費機制 服務品質(Quality of Service，QoS)：控制機制，針對不同用戶或者不同資料流採用相應不同的優先級，或是根據應用程式要求，保證資料流的效能達到一定水準

Functions of Packet Data Network (PDN) Gateway (P-GW) IP anchor point for bearers UE IP address allocation Per-user based packet filtering Connectivity to packet data network

P-GW Functionality Per-user based packet filtering Lawful Interception UE IP address allocation Transport level packet marking in the downlink UL and DL service level charging, gating and rate enforcement DL rate enforcement based on APN-AMBR (APN- Aggregate Maximum Bit Rate) One user can only be served by ONES-GW but more than one P-GW. Ref. 3GPP TS 23.401

HSS HSS (Home Subscribe Server)：負責身分認證的資訊、紀錄UE位置、紀錄UE網路能力等儲存許多關於安全性功能資料

Functions of Home Subscriber Server (HSS) Basically, the HSS (for Home Subscriber Server) is a database. HSS contains user-related and subscriber-related information. HSS also provides support functions in mobility management, call and session setup, user authentication and access authorization. It is based on the pre-3GPP Release 4 - Home Location Register (HLR) and Authentication Centre (AuC).

PCRF PCRF(Policy Charging Rule Function)：用於策略控制決策和實現基於流量計費的功能。

Functions of Policy, Charging & Rules Function (PCRF) Network control of Service Data Flow (SDF) detection, gating, QoS & flow based charging Dynamic policy decision on service data flow treatment in the PCEF (xGW) Authorizes QoS resources

LTE網路 - S1介面 eNB透過S1介面與核心網路通訊，S1介面分成 Control-plane：S1-MME介面(與MME連結) User-plane：S1-U介面(與S-GW連結)