# Research IV: Lightweight 5G Core (5G RedCap)

## Background Knowledge:

- Specification

- 3GPP Specification 23.501
- [RedCap 3GPP](https://www.3gpp.org/technologies/redcap) Specification 21.917

- API
- In 5GC, the connection between each Network Function using [OpenAPI](https://github.com/free5gc/openapi) is called SBI(Service Based Interface, below is the source code from Free5GC.
- Here is a [test note](https://hackmd.io/@ywZGdjNcRxeVSxyd3g0xAA/SkEnkd4Na) about API sever and client.
- You can also find some information about what is API by searching.

- Testing environment

- Free5GC is an open source 5G core network written in go language, which is convenient for E2E test without expensive hardware, you only need a computer or VM.
- Below is the notes of installing process,it included some solutions of bugs, if the process is not detailed enough, you can click the reference in it. [NOTE](https://hackmd.io/@ywZGdjNcRxeVSxyd3g0xAA/HJZuWfHXT)

- The note also include the below tools debugging process.

- Wireshark is a packet catching tool, we will use it to see the packet content between two testing device.

- MobaXterm is a ssh terminal tool, we can use it to connect to server where VM is running on.

- VScode is a code editor with ssh function, we can use it to modify the code remotely, you can also use other similar platform like Gateway (From Jetbrains), Goland (From Jetbrains), Sublime text.

## Milestone:

- Modify the packet parameters with “Authentication request”
- Remove “AUSF” & E2E test
- Remove “NSSF” & E2E test
- Remove “PCF” & E2E test
- Remove “UDR” & E2E test
- Remove “UDM” & E2E test
- Others
- SPEC study and a simlfied version
- 5GC call flow study & OpenAPI connection study