J. MOBILE NETWORK

A cellular network is a communications network specifically designed for mobile devices. It enables communication between these mobile devices and with all subscribers. In a cellular network, radio waves act as the link between the mobile device and the transmitter infrastructure.

1. GSM system (2G)

In 1982, the CEPT decided to standardise a mobile communication system in the 890–915 and 935–960 MHz bands for the whole of Europe. The GSM (Global System for Mobile Communications) standard was finalised in the early 1990s. GSM is a comprehensive digital system comprising all the elements necessary for a digital mobile communication system.

In a GSM system, the mobile station consists of two parts: the mobile equipment, which enables radio communication, and the identification module (SIM card), which contains the subscriber’s identification details.

The network is divided into cells, each of which has a base station (BTS — Base Transceiver Station) that handles radio transmissions. Each base station is connected to a base station controller (BSC — Base Station Controller).

The core network contains:

MSC (Mobile Service Switching Centre): a switch that communicates with the various radio systems.

HLR (Home Location Register): a database for managing permanent subscribers.

VLR (Visitor Location Register): a database of visitors in a cell.

In the radio access method used in GSM, TDMA/AMRT (Time Division Multiple Access), time is divided into 8 slots of 0.57 ms per radio channel. Speech is compressed into a 22.8 kHz bandwidth using error-correcting coding. The main obstacle facing a mobile radio telephony system is the narrowness of the available frequency band. Hence the idea of using a large number of low-power transceivers scattered throughout the territory (cellular network). When a mobile moves from one cell to another, the system performs an automatic handover (channel transfer) in a fraction of a second, without the user noticing.

2. GSM subsystems

· Radio subsystem: comprises the BTSs and BSCs (Base Station Controller). Manages the radio interface, radio resources and handover between cells.

· Network subsystem: contains the MSCs that provide interconnection between base stations and with other networks. It also contains the HLR (Home Location Register) and the VLR (Visitor Location Register).

· Operations and Maintenance Centre (OMC): enables the operator to manage their network.

3. The evolution of cellular standards

⚡ 5G — architecture and use cases

5G (IMT-2020 standard, also known as NR — New Radio) is based on three main categories of use cases: eMBB (enhanced Mobile Broadband, very high-speed broadband), URLLC (Ultra-Reliable Low-Latency Communication, latency < 1 ms for critical applications: autonomous vehicles, telemedicine) and mMTC (massive Machine Type Communication, very high-density IoT). 5G uses new frequency bands: sub-6 GHz (mid-band, good coverage) and mmWave / 26-28 GHz (very high-speed broadband over short distances). In France, 5G networks have been rolled out by national operators since 2020.

4. Wi-Fi connections

Wi-Fi is a wireless networking technology (WLAN) that enables shared network access within a home or business. Based on the IEEE 802.11 standard, Wi-Fi operates on the 2.4 GHz, 5 GHz and, more recently, 6 GHz frequencies.

Wi-Fi equipment includes interface cards (PCI, USB, integrated), access points (AP) or Wi-Fi routers/switches, directional or omnidirectional antennas, and repeaters or Mesh systems to extend coverage.

 ⚡ LiFi (Light Fidelity)

A future development of Wi-Fi is LiFi (IEEE 802.11bb), which modulates light waves (LEDs) to transmit data at very high speeds. The advantage is very high bandwidth and the absence of radio interference. The disadvantage is the need to be within the direct line of sight of the light source and sensitivity to opaque obstacles. Theoretical speeds of 224 Gbps have been demonstrated in the laboratory.

a) Business use: Wi-Fi 6/6E is the dominant standard

In the enterprise sector, Wi-Fi 6 and Wi-Fi 6E now form the foundation for new deployments and upgrades. Wi-Fi 6 meets everyday needs: employee mobility, video conferencing and light industrial IoT, with a controlled infrastructure across the 2.4 and 5 GHz bands. Wi-Fi 6E extends this capability to the 6 GHz band, offering less congested channels that are particularly useful in multi-tenant buildings or densely equipped campuses.

b) Business applications: Wi-Fi 7 on the horizon

Wi-Fi 7 (802.11be), for which the first professional-grade devices have been available since 2024, is beginning to feature in tenders for infrastructure projects scheduled for 2026–2028. Its benefits — theoretical speeds of up to 46 Gbps, MLO (Multi-Link Operation) enabling the simultaneous aggregation of multiple bands, and reduced latency — are aimed at emerging applications such as mobile mixed reality, uncompressed video streams, and Wi-Fi/wired convergence in edge data centres. For the majority of businesses, it represents a planned evolution

5. WiMAX

WiMAX (IEEE 802.16) is suitable for suburban and even rural areas that lack a usable fixed-line telephone infrastructure. It provides data rates of several tens of Mbps over a coverage area spanning several tens of kilometres. Depending on the frequency bands used, WiMAX can serve as a simple extension of Wi-Fi or as a convergence of Wi-Fi and third-generation cellular networks (UMTS or 3G).