# 陳毅 - 讀書會 - 21/07/02

:::info
- [x] 閱讀 Netmanias-01-LTE Network Architecture - Basic
:::

## 推薦連結

- [LTE 架構、協定與效能 ](http://speed.cis.nctu.edu.tw/~ydlin/miscpub/YHGuo-LTE.pdf)
- [LTE tutorial](https://www.tutorialspoint.com/lte/lte_network_architecture.htm)
- [NAS/MAC/PHY各司其職　LTE通訊協定預埋4G伏筆](https://www.2cm.com.tw/2cm/zh-tw/tech/848B4DFB7B584537B42D0006E1EB6523)
- [一分鐘快速了解手機如何傳送檔案](https://medium.com/@RiverChan/%E4%B8%80%E5%88%86%E9%90%98%E5%BF%AB%E9%80%9F%E4%BA%86%E8%A7%A3%E6%89%8B%E6%A9%9F%E5%A6%82%E4%BD%95%E5%82%B3%E9%80%81%E6%AA%94%E6%A1%88-c18cb584519f)

## EPC
### Features
- End-to-end Internet Protocol (All-IP)
- Clear delineation of control plane and data plane
- Simplified architecture: flat-IP architecture with a single core

### Versatilities
EPC enables operators to deploy and oprate 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).
### Control Plane
- Mobility across networks(and operator domains)
- Distributed mobility management
- Massive increase in scalability
- Dynamic policy management

### User Plane
User Plane has many common attributes with fixed broadband
- Broadband capacity
- QoS from multi-service delivery
- Per-user and per-application policies
- Highly available network elements
## EPC elements

### Serving Gateway(SGW)
Serving a large number of eNodeBs, focus on scalability and security.
#### features
- Local mobility anchor for inter-eNB handovers
- Mobility anchoring for inter-3GPP handovers
- Idle mode DL packet buffering (資料上下行)
- Lawful interception (資料擷取)
- Packet routing and forwarding
- LTE, 2/3G system switching
### Packet Data Network(PDN)Gateway(PGW)
- IP management (**IP anchor**), connection to external data networks
- Focus on highly scalable data connectivity and QoS enforcement
- UE IP address allocation
- Connectivity to packet data network
- 搭配 PCRF 可以做到統計、監控用戶使用流量
### Mobility Management Element(MME)
- Control-plane element
- Mobility management and connection management (up to thousands of eNodeBs)

#### features
- NAS Security
- Authentication
- Tracking area list management
- Idle State Mobility Handling
- Idle mode UE reachability
- EPS Bearer Control
- MME Selection for handovers with MME change
- S/GW, PDN/GW selection
- Inter core network node signaling for mobility between 2G/3G and LTE (handover)
- Support for ETWS message transmission
### Policy and Charging Rules Function(PCRF)
- network-wide control of flows:
- detection
- gating
- QoS (User 的服務頻寬)
- flow-based chrging
- authorized network-wide use of QoS resources. (manages millions of service data flows)
- Dynamic policy decision on service data flow treatment in the PCEF (xGW)
### Home Subscriber Server(HSS)
- Basically, the HSS is a database.
- HSS contains user-related and subscriber-related information (位置、網路能力、身分認證).
- It is based on the pre-3GPP Release 4 - Home Location Register (HLR) and Authentication Centre (AuC).
#### features
HSS provides support functions in
- mobility management
- call and session setup
- user authentication
- access authoriztion

## E-UTRAN
E-UTRAN provide E-UTRA protocol terminations towards UE
- user plan (PDCP/RLC/MAC/PHY)
- control plan (RRC)

### E-UTRAN Overall Architecture
- eNBs are interconnected with each other by X2 interface
- eNBs are connected by S1 interface to EPC
- to MME by S1-MME interface
- to Serving Gateway by S1-U interface

### Functions at eNodeB
- Radio Bearer Control
- Radio Admission Control
- Connection Mobility Control
- Dynamic allocation of resources to UEs in uplink, downlink and sidelink (sheduling)
- IP header compression and encryption
- Selection of an MME at UE attachment
- Routing of User Plane data towards Serving Gateway
- Scheduling of UL and DL data
- paging messages
- broadcast information
- PWS (public warning system)
- Measurement and measurement reporting configuration for mobility and scheduling

### UE and E-UTRAN

- Layer 1
- PHY
- Layer 2
- PDCP
- RLC
- MAC
實體層傳輸電波轉換為數位訊號

- Layer 3
- IP
- RRC
行動管理用戶資料 IP 封包
- EMM
- TCP/UDP

### UE
- SIM card
- Message en/decryption