Pre-Internship and internship Notes by William
===
＠NTUST, Taiwan
[Contact us]([e-mail])

###### tags: `Logs`
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##### [<center>Root Page</center>](https://hackmd.io/i5BFIooYTKyT7B1JUfAznA?view)
>Name: William Christian
>E-mail: [e-mail]
>HackMD: [My HackMD Account](https://hackmd.io/@williamcg00)
>Target Topic: Near-RT RAN Intelligent Controller
_________________________
##### <center>Minutes of Meeting(MoM)</center>
**Personal meetings:**
* [1st Introductory Meeting with Yueh and Tori (22/01/29)](https://hackmd.io/q6euNABHQQWZ8T7hOiW32Q)
* [1st RIC Team Meeting (22/06/28)](https://hackmd.io/JjHWJqSZQkarN5uSihsWqA)
* [6th Week Meeting (22/06/28)](https://hackmd.io/3w43We5vR82bVRkSLwKPRg)

_________________________
##### <center>Weekly Report</center>

## Pre-intern Notes

### Week 01 (22/02/14 - 22/02/20) : The preliminary knowledge on 5G as a foundation to understand Open RAN
- [Daily Logbook](https://hackmd.io/7aZOthNzS8mCO0zYUazc4A?view)
- What is 5G and how's it differ from the predecessor(4G)? ([22/02/15](https://hackmd.io/FwXWaZKuQ9mLyVIZb-LRtg))
- General introduction to Open RAN from a non-technical perspective ([22/02/17](https://hackmd.io/t_51ysrpQB27-I9uCm_RrA?both))

:::danger
**Day Offs**
- 22/02/14 was my recovery day from covid-19.
:::
:::success
**Goals**
- [x] To understand the basic elements of access network in 4G LTE and some of the novel things in 5G evolution
- [x] To understand the basic and frequently-used terminology when discussing about open RAN

**What I have learned**
- The network architecture of LTE is comprised of three components: UE, E-UTRAN, and EPC
- 5G is not just about increase of speed or bandwidth. Instead, 5G represents a restructuring of the access network in a way that utilizes several key trending technology
- Open RAN is a movement in disaggregating hardware and software
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### Week 02 (22/05/23 - 22/05/29) : The basic architecture of cellular & radio access network
- [Daily Logbook](https://hackmd.io/7aZOthNzS8mCO0zYUazc4A?view)
- The constructs of a cellular access network ([22/05/23](https://hackmd.io/gNIrkxoMRO64-4wJWuiWwA))
- The 'connecting network' between base station and mobile core ([22/05/25](https://hackmd.io/iXX3knj2Q0-pk9-TLufMJw))
- The 1st, 2nd, and 3rd split of Radio Access Network ([22/05/27](https://hackmd.io/Mni1V0tARRmowPksPNLcPQ))

:::success
**Goals**
- [x] To comprehend the role of base station and mobile core in providing user equipment connections to the internet
- [x] To understand how packet is processed in-between the mobile core and base station
- [x] To understand the 3(three) progressive splits of RAN and the meaning behind them

**What I have learned**
- A cellular network consists of two main subsystems: the RAN and the Mobile Core
- Radio Resource Control function is to configures the coarse-grain and policy-related aspects of the pipeline(run on the control plane)
- Near-RT RIC implemented as an SDN Controller hosting a set of SDN control apps
:::
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### Week 03 (22/05/30 - 22/06/05) : The advanced capabilities as the significant benefits of disaggregating RAN
- [Daily Logbook](https://hackmd.io/7aZOthNzS8mCO0zYUazc4A?view)
- Capabilities #1: Optimized data plane ([22/05/30](https://hackmd.io/EXkmiVfBTyO7-d1zI5HSkA#-Capabilities-1-Optimized-data-plane-))
- Capabilities #2: Multi Cloud ([22/06/1](https://hackmd.io/EF888afKQgqmS_VImBFZEA))
- Capabilities #3: Network Slicing ([22/06/3](https://hackmd.io/wYl6MyvYRMe2vnaUxPl8Ng))

:::success
**Goals**
- [x] To understand the benefits of seperating RAN into control and data plane
- [x] To understand the reason and benefits behind placing different functions in different physical location
- [x] To understand the mechanism involved in the RAN and core slicing

**What I have learned**
- Decoupling control and data paths enables them to be optimized independently(recall the SDN principle)
- Multi cloud allows different functions can be placed in different physical locations
- The idea of the RAN slicing is to perform a second mapping of Virtual RBs to Physical RBs
- The slices of mobile core would scale independently depending on their respective workloads and QoS guarantees
:::
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## Summer Intern Notes

### Week 04 (22/06/25 - 22/07/01) : FlexRIC fundamentals and OAI software installation
- [Daily Logbook](https://hackmd.io/7aZOthNzS8mCO0zYUazc4A?view)
- Installation of OAI-CU and OAI-DU ([2022/06/28](https://hackmd.io/BFqA4iXGRXOi56wDP9ewyA?both))
- Study the connection between FlexRIC and openairinterface5g's software installed ([2022/07/01](https://hackmd.io/HK3SW41iQNGfTLY56Wkt5g?both))
:::success
**Goals**
- [x] To understand more about flexRIC architecture and the E2 agent functionality and configuration.
- [x] To install the openairinterface5G software(checkout different branches) and debug the installation errors

**What I have learned**
- FlexRIX is a SDK that embodies O-RAN standardization in its flexible controller implementation
- Installer must pay attention to several parsed arguments in installing the OAI5G software, particularly in enabling it to be integrated with FlexRIC

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### Week 05 (22/07/02 - 22/07/08) : Moving the installation into Lab's VM
- [Daily Logbook](https://hackmd.io/7aZOthNzS8mCO0zYUazc4A?view)
- To build and run the OAI gNB on the Lab's VM[ (2022/07/08)](https://hackmd.io/JkuGcYsDT-KJV8IVhBTnmw)

:::success
**Goals**
- [x] To show the steps to build and run the gNB on lab’s VM

**What I have learned**
- Installer might need to consider different installation point(different VM) between the OAI5G and the FlexRIC

:::
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### Week 06 (22/07/09 - 22/07/15) : The gNB-facing patch file and FlexRIC-OAI integration
- [Daily Logbook](https://hackmd.io/7aZOthNzS8mCO0zYUazc4A?view)
- To understand the FlexRIC's patch on OAI5G software [(2022/07/13)](https://hackmd.io/t8rahkUARO2XsZPzFIZGLA)
- To review the theoritical concept regarding the architecture of the FlexRIC agent library, the specific functionality of the building blocks of the base station's pipeline, etc. (the exhaustive list could be seen on references) [(2022/07/13)](https://hackmd.io/t8rahkUARO2XsZPzFIZGLA)
- To describe sm_ag_if_ans.h, mac_data_ie.h, rlc_data_ie.h, pdcp_data_ie.h, and slice_data_ie.h [(2022/07/14)](https://hackmd.io/t8rahkUARO2XsZPzFIZGLA)
- To understand libe2_agent.a, sm_ag_if_rd.c, sm_ag_if_rd.h, and sm_io.h [(2022/07/15)](https://hackmd.io/t8rahkUARO2XsZPzFIZGLA)
:::success
**Goals**
- [x] To disect and understand the FlexRIC’s OAI patch on OAI 5G’s software.

**What I have learned**
- The patch implements several IEs in a form of struct, especially on RAN-related IEs
- The patch also implements several modification on each of the DU components so each of them has a struct to convey indication-related data

:::
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### Week 07 (22/07/16 - 22/07/22) : Deeper on the FlexRIC's patch on the OpenAirInterface software
- [Daily Logbook](https://hackmd.io/7aZOthNzS8mCO0zYUazc4A?view)
- Discuss with Yueh-Huan about the detailed information ([2022/07/18](https://hackmd.io/t8rahkUARO2XsZPzFIZGLA?both))
- To understand the connection configuration file on OAI5G ([2022/07/19](https://hackmd.io/t8rahkUARO2XsZPzFIZGLA?both))
- To complete the description of the patch file and draw the final relationship diagram ([2022/07/19](https://hackmd.io/_52Y1E13ReWEC1ZYOol2Rg))
:::danger
**Day Offs**
- 22/07/20 was a break for me attending a test.
:::
:::success
**Goals**
- [x] To show the correlation between FlexRIC’s architecture and the implemented source code, as well as giving a general description about the workflow.

**What I have learned**
- Initialization of E2 agent is a complex process involving several derivative procedures.
:::
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### Week 08 (22/07/23 - 22/07/29) : Notes improvement and further study on E2 Agent
- [Daily Logbook](https://hackmd.io/7aZOthNzS8mCO0zYUazc4A?view)
- A dedicated page for IE(Information Elements) implementation[ (2022/07/27)](https://hackmd.io/ho-65FNFRPiJkV-5u88NJQ#12-Procedures-related)
- Integrate Anna's mapping to my mapping[ (2022/07/28)](https://hackmd.io/_52Y1E13ReWEC1ZYOol2Rg)

:::success
**Goals**
- [x] To improve the notes created in previous weeks

**What I have learned**
- Each note should focus on presenting a single idea

:::
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### Week 09 (22/07/30 - 22/08/05) : Notes revision on diagrams and re-patching the OAI5G using FlexRIC's dev branch
- [Daily Logbook](https://hackmd.io/7aZOthNzS8mCO0zYUazc4A?view)
- Revise architecture mapping
- Patch the OAI using FlexRIC's dev branch

:::success
**Goals**
- [x] To repatch the OAI5G software according to FlexRIC's dev branch

**What I have learned**
- The dev branch's patch offers a unique feature of RIC and also completing some missing implementation
:::
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### Week 10 (22/08/06 - 22/08/12) : Further study on the Agents inside the E2 Agent
- [Daily Logbook](https://hackmd.io/7aZOthNzS8mCO0zYUazc4A?view)
- Study how the components of E2 agent in handling E2AP message and E2SM message ([2022/08/08-12](https://hackmd.io/itWAhkxATZG-pTdRAvw6Lw))

:::success
**Goals**
- [x] To explain how the E2 agent components work in handling the E2AP and E2SM messages.

**What I have learned**
- To comprehend the implementation of FlexRIC's E2 Agent, one should oversee several concept such as I/O multiplexing, red-black tree structure, etc.

:::
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### Week 11 (22/08/13 - 22/08/19) : Drawing diagrams and explanations of E2 Agent source code
- [Daily Logbook](https://hackmd.io/7aZOthNzS8mCO0zYUazc4A?view)
- Draw the block diagram and flowchart for the E2 agent workflow ([2022/08/16-19](https://hackmd.io/itWAhkxATZG-pTdRAvw6Lw))

:::success
**Goals**
- [x] To explain how the E2 agent components work in handling the E2AP and E2SM messages.

**What I have learned**
- The implementation allows the E2 agent to be started independently on a thread.

:::