📡 Private 5G Network Setup

This repository documents the end-to-end setup of a real-time 5G network using:

• Open5GS as the 5G Core
• srsRAN as the Radio Access Network (RAN)
• USRP B210 as the base station hardware
• Connected to Commercial Off-The-Shelf (COTS) 5G devices (smartphones)

✅ Fully tested with Samsung S23 and OPPO Reno 5G using OpenCell SIM cards.

🛠 Requirements

Component	Purpose
Ubuntu 22.04 LTS	Operating system for running Open5GS & srsRAN
USRP B210	Software-defined radio hardware acting as the 5G base station
OpenCell SIM	SIM cards for registering UEs with the 5G core
COTS UE	5G smartphones for testing connectivity

💡 Tip: Install Ubuntu on bare metal (dual boot recommended) instead of using a virtual machine for better hardware performance and less probability of the errors.

🚀 Setup Guide

Follow the steps in the Steps-1-7 folder for a detailed walk-through.

High-Level Process

1. Open5GS Setup – Install and configure the 5G Core network.
2. UHD Drivers Installation – Set up USRP B210 drivers for hardware communication.
3. srsRAN Setup – Configure the Radio Access Network.
4. Open5GS WebUI User Creation – Register UE subscribers in the 5G Core.
5. SIM Writing – Program OpenCell SIM cards with matching IMSI & keys.
6. COTS UE Configuration – Configure mobile phones for private 5G connection.
7. Connectivity Test – Verify registration, attach procedure, and data transfer.

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🧠 Open5GS – The Core Network

Open5GS is like the brain of the mobile network.
It handles device registration, authentication, IP address allocation, mobility, and data routing.

Main Functions

• AMF (Access and Mobility Management Function)

  • Think of it like airport security — it checks who’s coming in (authentication) and makes sure they stay connected as they move around.
  • Handles UE registration, authentication, and handovers.

• SMF (Session Management Function)

  • Like a traffic planner — it gives each device an IP and decides how their data will travel.
  • Manages session creation and modifies data paths.

• UPF (User Plane Function)

  • The actual data highway — where user internet traffic flows in and out.
  • Forwards data between the UE and the internet/application servers.

• PCF (Policy Control Function)

  • The rulebook — decides speed limits, QoS, and access policies for each device.
  • Enforces policies set by the network.

• NRF (Network Repository Function)

  • The phonebook — keeps track of where each function (like AMF, SMF) is running.
  • Helps network functions discover and communicate with each other.

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📡 srsRAN – The Radio Access Network

srsRAN is like the hands and ears of the network.
It uses software-defined radios (SDR) like the USRP B210 to send and receive wireless signals to the devices (UEs).

In my setup, srsRAN acted as the 5G gNB (base station), which is split into:

• RU (Radio Unit) – Sends and receives signals over the air to/from the devices.
• DU (Distributed Unit) – Handles real-time functions such as scheduling and MAC/RLC processing.
• CU (Central Unit) – Manages non-real-time functions like RRC signaling, mobility, and links the radio to the Open5GS core (via NG interfaces).

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🔗 How They Work Together

1. UE connects to gNB (via srsRAN with USRP B210).
2. gNB forwards control signaling and data to Open5GS core functions.
3. AMF authenticates the UE, SMF assigns an IP, UPF routes the traffic, and PCF applies policies.
4. NRF ensures all functions can find each other and work together.

📌 In short:

• Open5GS = network brain.
• srsRAN + USRP B210 = base station.
• Together, they form a complete private 5G setup for research and testing.

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🖼 Conceptual Diagram

• COTS -> Base station(Tower) -> Network CORE -> Internet

[UE] ⇄ [USRP B210 -> srsRAN] ⇄ [Open5GS] ⇄ Internet