Different wireless technologies are built for different distances and speeds. NFC (Near Field Communication) works over just a few centimetres and is used for contactless card payments and tapping phones together to share data. Cellular networks — 4G and 5G — provide internet access across kilometres using a grid of radio masts, making mobile broadband possible anywhere with coverage.
What is NFC?
Near Field Communication (NFC) is a short-range wireless technology that operates at 13.56 MHz and transfers data at up to 424 kbps over a maximum distance of approximately 4 centimetres.
NFC works through electromagnetic induction: two NFC-capable devices (or a device and a passive tag) create a magnetic field between their antennas when held close together. The field can even power a passive NFC tag (such as a payment card chip) without needing a battery.
Where NFC is used:
- Contactless payments: Tap your debit card or phone at a shop terminal — the payment data is transmitted over NFC.
- Oyster/transport cards: The London Oyster card and contactless bank cards use NFC to communicate with barriers.
- Access control: Building entry cards and hotel room keys use NFC tags.
- Data sharing: Android Beam (now discontinued) and Apple's AirDrop (partly NFC-initiated) used NFC to start a connection between phones.
- Smart labels: NFC tags embedded in posters or products store a URL or data that a phone reads automatically when tapped.
The extremely short range of NFC (4 cm) is a deliberate security feature: an attacker would need to be physically touching you to intercept a transaction.
What is a cellular network?
A cellular network divides a geographic area into hexagonal regions called cells, each served by a base station (radio mast). Mobile devices connect to the nearest base station, which relays data to the core network (and from there to the internet). As a user moves between cells, calls and data sessions are handed off seamlessly between base stations.
The word "cellular" comes from this cell structure — the network literally resembles a honeycomb of cells.
Generations of cellular networks:
| Generation | Standard | Launched | Typical download speed | Key feature |
|---|---|---|---|---|
| 1G | Analogue | 1980s | Voice only | First mobile phones |
| 2G | GSM | 1991 | Up to 50 kbps | Digital voice, SMS |
| 3G | UMTS/HSPA | 2000s | 1–10 Mbps | Mobile internet |
| 4G | LTE | 2009–2012 | 10–150 Mbps | HD video streaming |
| 5G | NR | 2019+ | 100 Mbps – 10 Gbps | IoT, autonomous vehicles |
How does 4G work?
4G LTE (Long Term Evolution) uses radio waves in multiple frequency bands (700 MHz to 2.6 GHz in the UK). Lower frequencies travel farther but carry less data; higher frequencies carry more data but require more base stations because the signal does not travel as far.
4G transmits data using OFDM (Orthogonal Frequency Division Multiplexing) — splitting a signal across many subcarriers simultaneously, making efficient use of the available spectrum and reducing interference. Modern 4G typically provides download speeds of 20–100 Mbps in urban areas.
How does 5G differ from 4G?
5G NR (New Radio) introduces three new capabilities:
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Higher frequencies (millimetre wave, 26–28 GHz): Extremely high data rates (up to 10 Gbps) but very short range (hundreds of metres) and poor penetration through walls. Used in dense urban areas and stadiums.
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Sub-6 GHz bands: Similar frequencies to 4G but using wider channels and better antenna technology (massive MIMO — many antennas transmitting simultaneously). Offers 100 Mbps – 1 Gbps with good coverage.
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Ultra-low latency (1–5 ms): 4G latency is typically 20–50 ms. 5G's near-instant response enables real-time control of remote machines, autonomous vehicles, and remote surgery — applications where a 50 ms delay could be catastrophic.
Comparing wireless network technologies
| Technology | Max range | Typical speed | Power use | Use case |
|---|---|---|---|---|
| NFC | ~4 cm | 424 kbps | Very low (passive tags use none) | Payments, access cards |
| Bluetooth 5 | ~10–400 m | Up to 2 Mbps | Low | PAN (earphones, keyboards) |
| Wi-Fi (802.11ac) | ~50–100 m | Up to 1 Gbps | Moderate | LAN (home, office, school) |
| 4G LTE | ~1–10 km per cell | 10–150 Mbps | Moderate–high | Mobile internet |
| 5G NR | ~200 m–10 km | 100 Mbps–10 Gbps | Moderate–high | Mobile internet, IoT, vehicles |
Frequently asked questions
Is NFC the same as Bluetooth?
No. Both are wireless technologies but they work differently and suit different tasks. NFC operates over at most 4 centimetres and takes a fraction of a second to initiate — ideal for payments and quick taps. Bluetooth covers up to 10 metres (or more) and is designed for continuous connections — ideal for earphones, keyboards, and file transfers. Some devices use NFC to initiate a Bluetooth pairing automatically (tap to pair).
Why do we still use 4G if 5G is faster?
5G coverage is still being rolled out — as of 2024, 5G reaches most UK cities and many large towns, but rural areas largely rely on 4G and 3G. 5G base stations (especially millimetre-wave) are expensive and require very dense deployment. 4G is sufficient for most everyday tasks: browsing, video calls, and streaming. 5G becomes essential only for applications that need massive speed or ultra-low latency.
How does a mobile phone know which cell to connect to?
Mobile phones continuously monitor signal strength from nearby base stations. They connect to the base station with the strongest signal. When a user moves and signal from a new base station becomes stronger, the network coordinates a handover — transferring the connection smoothly to the new base station, ideally without the user noticing any interruption. This is why phone calls do not drop when you walk between buildings.
Can NFC be used to spread malware?
In theory, yes — a malicious NFC tag could attempt to open a URL or trigger an action on a phone that taps it. In practice, modern phones display a confirmation screen before following an NFC link to an unfamiliar site, and the 4 cm range limits the opportunity for an attacker. The risk is far lower than Wi-Fi or Bluetooth attacks. Standard advice applies: do not tap your phone against unknown NFC tags in public.
Professor Turing at aitutors.me is ready to guide you through every layer of networking — from the NFC chip in your pocket to the global internet backbone.