# 5G微不足道小筆記 (持續增加中)
###### tags: `5G`

## LTE or 5G 三層架構：
3rd: RRC等
2nd: MAC、RLC、PDCP等
1st: PHY
key word: 5G stack or LTE stack

※上述1st、2nd以及3rd都是符合OSI七層架構的，上述的MAC、RLC以及PDCP等為3G、4G或5G在第一、二或是第三層所實作的方式或是協定

## UE(or EPC)、RU、CU and DU
UE/CPE: Like mobile phone or others
RU: Radio Unit (That weird machine provided by ALPHA.inc)(作用極相似基地台)
CU: Centralized Unit (CB-1921A-AA1)
DU: Distributed Unit (CB-1921A-AA1)

## Control Plane and Data Plane
當手機(UE/CPE)要使用網路時
1. 先經過Control Plane，Control Plane會審核使用者的資料(Ex.電信資費方案、該方案所能獲得的網路頻寬、繳費情形等等)
1. 完成Control Plane的程序之後，電信業者(?)會留通道給手機(UE/CPE)，手機透過無線網路(3G/4G/5G)傳輸/接收資料則是以Data Plane的方式進行

## 5G structure
* 虛線處為control
* 實線處為data
1. AUSF：Authentication Server Function
2. AMF：Access and Mobility Management Function
3. AF：Application Function
4. DN：Data Networks
5. SMF：Session Management Function
6. NEF：Network Exposure Function
7. NSSF：Network Slice Selection Function
8. NRF：Network Repository Function
9. PCF：Policy Control Function
10. UPF：User Plane Function
11. RAN：Radio Access Network

## 4G structure
4G control plane 和 data plane 分別不明確

## 5G control plane procedure

https://www.eventhelix.com/5G/standalone-access-registration/5g-standalone-access-registration.pdf

## 需要 Study 的內容
* control plane and data plane
* GTP tunnel (GPRS)
* EPC (Evolved Packet Core) and ENB (eNodeB) structure
* HSS、MME、sGateway and pGateway included in EPC
* linux namespace (Concept of Docker)
* openflow
* SDN: control plane separate from data plane
* What is control plane => protocol we used
* PDCP in L1