What is 4G?

How 4G LTE Works

4G LTE (Long-Term Evolution) is a radio communication standard that replaced 3G from around 2012 onwards. It uses OFDMA (Orthogonal Frequency Division Multiple Access) — a technique that divides available spectrum into many small sub-channels, allowing multiple users to share capacity efficiently without interfering with each other.

A 4G network has two main parts: the radio access network (RAN), which includes the masts and antennas that communicate wirelessly with your phone; and the Evolved Packet Core (EPC), which is the software-defined backbone that routes data between your device and the internet. When you load a website on 4G, your request travels via radio waves to the nearest mast, then via fibre to the mobile core, and out to the internet — the whole round trip takes 30–60 milliseconds.

Frequency bands used in UK 4G

UK 4G networks operate across several frequency bands, each with different characteristics:

• 800 MHz (Band 20): the "coverage band". Long range, excellent building penetration. Used by all four UK networks to reach rural areas and indoor coverage. If you have 4G in a remote location or a basement, it's almost certainly on 800 MHz.
• 1800 MHz (Band 3): the primary urban 4G band. Good balance of range and capacity. EE's original 4G spectrum was largely on 1800 MHz.
• 2100 MHz (Band 1): previously 3G spectrum, now used for 4G in many urban areas.
• 2600 MHz (Band 7): the "capacity band". Short range, high speed. Used mainly to boost capacity in dense city centres.
• 1400 MHz (Band 32) and 2300 MHz (Band 40): supplementary bands used by some operators for additional capacity.

LTE-Advanced (LTE-A) combines multiple bands simultaneously — a technique called carrier aggregation — to deliver higher speeds. Modern 4G phones automatically select the best combination of bands available.

4G vs Previous Generations

The leap from 3G to 4G was the most significant improvement in mobile data capability since the internet came to phones. The jump wasn't just about speed — it was a fundamental change in network architecture that made mobile data practical for everyday use.

What changed from 3G to 4G?

• Architecture: 3G networks (UMTS/HSPA) had a complex, circuit-switched heritage designed for voice calls. 4G is all-IP from the ground up — everything, including voice calls (via VoLTE), travels as data packets. This eliminates the inefficiency of maintaining dedicated voice circuits.
• Spectrum efficiency: 4G transmits roughly 3× more data per unit of spectrum than 3G, meaning operators can serve more users at higher speeds from the same radio frequencies.
• Latency: 3G latency was typically 80–150ms. 4G reduced this to 30–60ms, making real-time applications like video calls and online gaming practical on mobile.
• MIMO antennas: 4G introduced multiple antenna systems that transmit separate data streams simultaneously, multiplying throughput without needing more spectrum.

Indoor and Outdoor 4G Coverage

Signal bars on your phone indicate your connection to the nearest mast — but indoor signal quality depends heavily on what's between you and that mast. Building materials absorb and reflect radio waves to varying degrees.

Why indoor coverage varies so much

A building's construction has a dramatic effect on 4G signal. Modern buildings with low-emissivity (Low-E) glass — designed to be energy-efficient — can attenuate radio signals by 20–30 dB, roughly a 1,000-fold reduction in signal power. Reinforced concrete walls, metal cladding and underground locations present similar challenges.

O2 consistently ranks best for indoor 4G in independent UK tests. This reflects both spectrum strategy — heavier use of 800 MHz, which penetrates buildings better than higher frequencies — and investment in indoor infrastructure solutions like small cells and distributed antenna systems (DAS) in major venues and offices.

If indoor coverage at a specific address matters to you (working from home, for example), the best approach is to test signal with a SIM card rather than relying on coverage maps, which show outdoor signal projections.

4G Coverage in the UK — by Network

4G was introduced to the UK by EE in October 2012. The other three networks — O2, Vodafone and Three — launched 4G in 2013. By 2024, outdoor 4G population coverage across all four networks exceeds 99%.

Population coverage and geographic coverage are very different figures. A network that covers 99% of the population may cover only 75–80% of the UK's land area — because the remaining 1% of population (roughly 670,000 people) are spread across a vast rural geography. The Shared Rural Network (SRN) is a government-backed programme requiring all four operators to extend 4G to areas currently with no coverage, with a target of 95% geographic coverage by 2025.

What Can You Do with 4G?

4G LTE at typical UK speeds (20–80 Mbps) handles every mainstream mobile data task with ease:

• Video streaming: Netflix, Disney+, YouTube — 4K streaming requires around 25 Mbps; HD needs 5 Mbps. Both are well within 4G capabilities in most locations.
• Video calls: WhatsApp, FaceTime, Teams, Zoom — HD video calls use 1.5–3 Mbps. 4G is more than sufficient, and VoLTE (Voice over LTE) delivers voice calls with CD-quality audio.
• Cloud gaming: services like Xbox Cloud Gaming and GeForce NOW need 10–20 Mbps with consistent latency. Urban 4G handles this; rural 4G may struggle with latency.
• Mobile working: email, document editing, video conferencing, file uploads — all practical on 4G. Large file transfers are slower than on fibre but workable.
• Home broadband: 4G home broadband is a genuine alternative to DSL or cable in many areas, especially rural locations underserved by fixed-line infrastructure.

4G vs 5G — Do You Need to Switch?

For most UK users in 2024, 4G is sufficient for every everyday task. The practical case for switching to 5G depends on your specific circumstances:

• You work in a dense city centre: mid-band 5G can deliver 300+ Mbps vs 50 Mbps on 4G, and handles congestion much better during peak hours.
• You frequently use mobile data in crowded venues: 5G's capacity advantage makes a meaningful difference at football grounds, festivals and conferences.
• You're in a rural or suburban area: low-band 5G (if available) is only marginally faster than 4G. The practical benefit is limited unless mid-band 5G reaches you.
• You're on a budget: 4G SIM plans are typically cheaper than 5G equivalents. If 4G meets your needs, there's no cost pressure to switch.

The best way to know whether 5G is worth it for you is to check what type of 5G is available at your specific locations and compare it with current 4G performance.

Frequently Asked Questions