<h1>TEEP Week one : 5G Core and RAN Introduction</h1>

<h2>RAN Introduction</h2>


<p>
RAN stands for Radio Access Network. It's a key part of a mobile telecommunications system that connects individual devices to the core network of mobile operator.
</p>

<h2>5G Introduction</h2>
<p>5G is the fifth generation of wireless communication technology which enhance the 4G LTE technology which more faster, reliable, and connected with mass devices. 5G can be deployed in two ways :


- **Non-Standalone (NSA)** : In the NSA approach, 5G is built on top of existing 4G infrastructure. This means that while your device might connect to a 5G radio for faster data, the core network still relies on 4G to handle things like signaling and control. It's a quicker and more cost-effective way to roll out 5G, but it doesn’t unlock all of 5G’s advanced features.
- **Standalone (SA)** : Standalone 5G uses a completely new 5G core network along with 5G radios, allowing both control and data to operate on true 5G technology. This enables the full potential of 5G, including ultra-low latency, improved reliability, and advanced capabilities like massive IoT and network slicing.

There are many key features of 5G that make it a groundbreaking advancement in wireless communication :

- **Massive MIMO (Multiple Input, Multiple Output)**
Uses large arrays of antennas to send and receive more data simultaneously, greatly boosting network capacity and efficiency.
- **Beamforming**
A technique that directs wireless signals exactly where they’re needed, improving speed, reliability, and coverage.
- **Full Duplex Communication**
Enables devices to transmit and receive data at the same time on the same frequency, enhancing spectrum efficiency.
- **Small Cells**
Low-powered cellular nodes that enhance network coverage and capacity in dense urban environments by shortening the distance to users.
- **Millimeter Wave (mmWave) Spectrum**
Utilizes higher-frequency bands (above 24 GHz) to deliver ultra-high data rates, though with shorter range and penetration limits.
- **Network Slicing**
Creates multiple virtual networks on the same physical infrastructure, allowing customized services for different use cases (e.g., IoT vs streaming).
- **Edge Computing**
Brings computing resources closer to the end user to reduce latency and support real-time applications like AR/VR and autonomous systems.

There are three main Services of 5G:
- **eMBB (Enhanced Mobile Broadband)**
For high data rates, e.g., 4K/8K streaming, VR/AR.
- **URLLC (Ultra-Reliable Low Latency Communication)**
For mission-critical apps like autonomous vehicles and industrial robotics.
- **mMTC (Massive Machine-Type Communication**)
For IoT with a huge number of devices.


</p>

<h2>5G Architecture</h2>


<h3>A. 5G Core</h3>

<p>
5G Core Network is the backbone of the 5G architecture. It is fully cloud-native and based on a Service-Based Architecture (SBA). 5G Core split into two sections:

- **Control Plane** : In a 5G core network, the control plane handles signaling and network management functions. It's responsible for authentication, authorization, mobility management, and session establishment, ensuring reliable and high-performance communication.

| **Function** | **Full Name** | **Purpose** |
|:-------------|:-----------------------------------------|:--------------------------------------------------------------------|
| **AMF** | Access and Mobility Management Function | Manages device registration, authentication, mobility, and session connection setup. |
| **SMF** | Session Management Function | Manages session establishment, modification, and release (but not actual user data). |
| **PCF** | Policy Control Function | Controls network policies like Quality of Service (QoS) and charging rules. |
| **UDM** | Unified Data Management | Handles subscriber data, profiles, and access permissions. |
| **AUSF** | Authentication Server Function | Authenticates users to ensure secure access to the network. |
| **NRF** | Network Repository Function | Provides discovery and status of other network functions. |
| **NSSF** | Network Slice Selection Function | Helps select and allocate network slices based on user or service needs. |

- **User Plane** : User plane include User Plane Function to manages the actual user data (internet browsing, streaming, etc.) flowing between the RAN and external networks (like the Internet).

<h3>B. 5G RAN</h3>

<p>


5G RAN is the part of the network that connects users to the 5G Core via radio signals. 5G RAN splitted into CU and DU.

- **CU (Centralized Unit)** : Component that manages higher-layer protocol stacks and provides centralized control functions. It handles tasks like radio resource management, mobility management, and quality of service.

| **Protocol** | **Full Name** | **Function** |
|:---------------|:-------------------------------------------|:------------------------------------------------------------------------------|
| **S1AP/X2AP** | S1 Application Protocol / X2 Application Protocol | Legacy signaling protocols (from LTE) adapted for 5G, used for control signaling. |
| **UDP/GTP** | User Datagram Protocol / GPRS Tunneling Protocol | Transport protocols used to tunnel user data between network elements. |
| **SDAP** | Service Data Adaptation Protocol | Maps application-level data flows to QoS flows, enabling differentiated services. |
| **RRC** | Radio Resource Control | Manages connection setup, mobility, security, and control of radio bearers. |
| **PDCP** | Packet Data Convergence Protocol | Performs IP header compression, encryption, and retransmission handling. |

- **DU (Distributed Unit)** : component that handles the lower layers of the communication protocol stack.The DU processes real-time data and manages radio resources, preparing data for transmission and handling scheduling functions.

| **Protocol** | **Full Name** | **Function** |
|:---------------|:-------------------------------------------|:------------------------------------------------------------------------------|
| **RLC** | Radio Link Control | Ensures reliable data transfer via segmentation, reassembly, and ARQ. |
| **MAC** | Medium Access Control | Handles scheduling, multiplexing, and logical channel mapping. |
| **PHY** | Physical Layer | Converts data into radio signals and handles modulation, coding, and transmission. |

</p>
<h2>RAN Intelligence Controller (RIC)</h2>
<p>
RIC (RAN Intelligent Controller) is a software platform introduced in Open RAN to bring intelligence, automation, and programmability into the Radio Access Network.

| **Type of RIC** | **Full Name** | **Location** | **Response Time** | **Key Functions** | **Runs** |
|-----------------|-------------------------|---------------------|------------------------|------------------------------------------------------------------|--------------|
| **Non-RT RIC** | Non-Real-Time RIC | Centralized (cloud) | > 1 second | - Long-term optimization | **rApps** |
| **Near-RT RIC** | Near-Real-Time RIC | Edge (close to RAN) | 10 ms to 1 second | - Real-time RAN optimization| **xApps** |


</p>