Mobile network (3G, 4G, 5G): fundamental concepts and developments

Cellular Network Communication Basics
📌 A mobile network relies on base stations (antennas) covering a territory divided into cells, where a mobile connects to one specific antenna.
📡 A cell's size depends on terrain (plateaus, mountains) and building density; denser urban areas require more base stations due to higher user concentration and signal attenuation.
🗣️ Voice communication is converted into a digital signal (bits), transmitted via an electromagnetic carrier wave, decoded by the base station, and routed through the core network (often fiber optics) to the recipient's base station.
⚙️ Core network intelligence involves controllers managing radio frequencies and handovers between cells, and routers establishing and maintaining connections.

Mobile Network Architecture and Location Management
💾 The network core features databases storing subscriber information (like location for routing incoming calls) and crucial data for encryption and authentication.
📱 A mobile device is identified by three elements: the IMSI (subscriber ID on the SIM card), the IMEI (device ID), and the MSISDN (phone number).
📍 When idle, the mobile's location is known coarsely via a Location Area (LA), a zone comprising several contiguous cells; mobiles periodically select the cell with the strongest received power.
🔄 If a mobile moves to a different LA, it triggers a location update transmitted to the core network databases, which is necessary for the paging procedure (waking the phone up for calls/SMS).

Evolution of Mobile Networks (2G to 5G)
💿 2G (GSM) introduced digital radio signals, voice transmission, and SMS, evolving from 1G's analog signal, operating mainly in circuit-switched mode.
📈 3G (mid-2000s) significantly increased data rates (via GPRS/EDGE, i.e., 2G+) to support mobile internet usage and the rise of smartphones, while still using circuit mode for voice.
🚀 4G (LTE), starting in the 2010s, shifted entirely to packet mode (Mobile All IP), abandoning circuit switching and relying on Voice over IP (VoIP), which reduced latency by removing network controllers.
🌟 5G aims for speeds up to 10 Gigabits/s and latency down to a few milliseconds, supporting massive Internet of Things (IoT) deployments and ultra-reliable low-latency communications (URLLC).

5G Architecture (Control and User Planes)
📡 The 5G architecture clearly separates the User Plane (handling user data transport like voice/data) and the Control Plane (handling security, authentication, and session management).
🔗 The User Plane involves the smartphone connecting to the base station, which links directly to the User Plane Function (UPF) Gateway for routing packets to the internet or the operator's IMS.
🧩 The Control Plane is more modular than 4G, incorporating functions like authentication and routing management within the core blocks, supported by the IP Multimedia Subsystem (IMS) for multimedia services.

Key Points & Insights
➡️ Mobile communication relies on a hierarchical structure involving base stations, controllers, and routers to manage signal transmission and routing.
➡️ Location tracking in idle mode uses Location Areas (LAs), where the mobile constantly measures signal strength to ensure the best connection before performing a full location update only when crossing LA boundaries.
➡️ The evolution from 2G to 4G marked a transition from circuit-switched (voice) to packet-switched (all data/VoIP) communication, significantly improving speed and reducing latency.
➡️ 5G architecture emphasizes modularity and the clear separation of user and control planes to achieve ultra-low latency and support diverse services like massive IoT.

📸 Video summarized with SummaryTube.com on Jan 25, 2026, 19:43 UTC