Understanding mobile phone networks

Currently they are provided and operated in the UK by three main commercial providers, known as Mobile Network Operators (MNOs): BT-EE, Virgin Media O2 (VMO2) and Vodafone Three.

In addition, there are more than 60 Mobile Virtual Network Operators (MVNOs) which use the networks owned by the MNOs. These include Giffgaff, Sky Mobile, Tesco Mobile, Lebara and others. When you take out a mobile service, it is vital to check the mobile coverage each MNO provides in the places you live, work and visit as each will be different. 

When you take out a mobile service, it is vital to check the mobile coverage each MNO provides in the places you live, work and visit as each will be different. 

How do mobile phone networks work?

A mobile network involves several different pieces of equipment to broadcast a mobile signal. Mobile signals are broadcast from antenna which are mounted on ground-based masts, rooftops and other existing structures (the macro network) at a height that provides a clear signal. 

Smaller antenna systems (small cells) provide a signal to areas which are difficult to reach or where additional capacity is needed, such as high-usage urban areas to ease congestion (e.g. train stations, stadiums etc). These signals connect with the mobile device.

The design of antenna and the location of masts or towers vary for all sorts of reasons:

• to accommodate the number of people and devices that will be using them – they will be smaller in cities and bigger in the countryside.
• because of local geography such as tall buildings, hills or valleys, which interfere with radio waves.
• where the base station can be sited, especially its height above the ground. This can be affected by planning considerations such as conservation areas which may impact the installation of base stations, access to electricity to power the radio transmitter and the layout and height of nearby buildings.
• the location of neighbouring mobile infrastructure whose radio transmissions could cause interference.

Lots of factors limit mobile connectivity, either slowing it down or stopping it altogether:

• simply having too many people trying to connect in the same cell at the same time can make it difficult to connect due to capacity constraints in the network.
• phones and tablets don’t always have access to the latest range of frequencies and can be limited by the size of their receiving antenna, so thick walls, hills, or other buildings can interfere with their ability to send and receive a signal to the mobile mast.
• distance from a base station can mean that a device is unable to connect due to the strength of the signal which degrades the further away a device is (although mobile phone networks do not require a line of sight).

What is meant by mobile signal?

In telecommunications, electromagnetic fields (EMF) are used to transmit information wirelessly via radio waves. These fields are created by the flow of electricity and are used in various communication technologies like mobile phones, Wi-Fi, and radio and television broadcasting.

Ofcom the national regulator, regularly measures electromagnetic field (EMF) emissions near mobile base stations. Taken under steady environmental conditions, these repeat audits allow them to observe any changes in EMF emissions over time. Their measurements have shown that levels are well within the general public EMF limits. Measurements are published on the Ofcom website at Electromagnetic field measurements near mobile base stations - Ofcom and include the latest local surveys.

The Department of Health (DoH) and the Public Health Agency (PHA) have a long-standing memorandum of understanding with the UK Health Security Agency (UKHSA) who publish advice on 5G technologies: radio waves and health - GOV.UK. UKHSA is committed to monitoring the evidence applicable to this and other radio technologies, and to revising its advice, should that be necessary.

What is meant by Radio Waves?

Radio waves are actually electromagnetic waves. Electromagnetic waves are made when a magnetic field and an electric field come together to make a wave. These waves include radio waves, visible light, ultraviolet light and x-rays.

Mobile phones work by sending and receiving low powered radio waves. The radio waves are sent to, and received from, a mast or aerial, called a mobile phone base station and a mobile phone. The base station then passes the signal/call into the landline network or on to the mast nearest the mobile phone the call is being made to. Each mobile phone base station covers an area known as a cell. Cells are aligned next to each other in a similar pattern to a honeycomb, and it is for this reason that mobile phone networks are sometimes referred to as cellular networks.

Base stations transmit and receive radio waves to connect the users of mobile phones and other devices to mobile communications networks. The strength of the radio waves from base station antennas reduces rapidly with increasing distance and the levels at locations where the public can be exposed tend to be small. Radio waves used to transmit mobile signal are non-ionising which refers to any type of electromagnetic radiation which does not carry enough energy to ionise atoms or molecules. In contrast, ionising radiation can ionise atoms or molecules and can be a serious health hazard.

The diagram below shows various types of electromagnetic waves. It is agreed that waves with characteristics on the right of this diagram are generally considered to be more hazardous to humans according to the International Commission for Non-Ionizing Radiation (ICNIRP).

Common household items such as microwave ovens, hairdryers, lightbulbs, wifi routers, baby alarms, Bluetooth devices and car remote key fobs all use radio wave technology which is non-ionising.

What is meant by 4G and 5G?

The ‘G’ stands for ‘Generation’. Mobile generations, from 1G to 5G, mark successive technological advancements with increasing speeds and capabilities: 1G introduced analog voice calls, 2G brought digital voice and SMS, 3G enabled mobile internet and smartphones, 4G (LTE) provided high-speed mobile broadband for streaming and apps, and 5G offers advanced, low-latency connectivity for Internet of Things (IoT) and new applications.

5G & 5G Standalone

5G is the fifth generation of wireless technology and the next generation of mobile networks after 4G. It can deliver faster, more reliable connection, and has lower latency (the time taken for data to travel from a source to a destination and back) than previous generations of wireless technology. Data requirements have increased 40% every year for the last decade, 5G is the only way mobile networks will be able to keep up with this demand. 

By providing the extra capacity that 5G affords, more users can avail of services when they want, where they want. 5G can help stimulate economic growth and achieve regional balance, especially in rural areas 5G’s increased speed and capacity allows more devices and users to access the internet at the same time. Non-standalone basic 5G which uses existing 4G infrastructure was launched in 2019 and coverage continues to extend across the UK.

Further information on 5G can be found on the Ofcom website at 5G mobile technology: a guide.

Average download speeds will range from 70 – 205Mbps. Theoretically speeds could evolve to 10-50Gbps in time. 5G compatible ‘smartphones’ support both 5G services and applications including:

• faster mobile broadband, greater capacity and a more consistent experience in congested areas with a very high number of devices. This can be beneficial for example at concerts, sporting events and transport hubs;
• industrial applications, enabling businesses to improve their productivity, for example through predictive maintenance and real-time analytics; and
• Internet of Things (IoT) services, many of which will help the public sector and businesses deliver services more efficiently.

Transitioning from basic non-standalone 5G, mobile operators have begun deploying standalone 5G (5G SA) which is the next evolution of 5G networks. Unlike Non-Standalone 5G (NSA), which uses 5G radio access but still relies on a 4G core, 5G SA requires the deployment of a 5G core. 

This allows for more functionality and benefits, including improved reliability, lower latency (near-instant communications), better security, and stronger indoor signal. The UK government has a stated ambition to deliver nationwide coverage of standalone 5G to all populated areas by 2030.

One of the key features of 5G SA is “network slicing,” which allows operators to offer multiple virtual, dedicated networks to individual customers or groups of customers. This enables a dedicated quality of service for specific network quality requirements leading to a number of use-cases and opportunities which are noted below.

There are already some examples of how 5G standalone is benefitting the NI economy:

• Belfast Harbour is harnessing 5G-led innovations to accelerate the digitisation of port operations including automatic bulk freight handling and safety improvements.  Harlander is the first self-driving passenger service in Northern Ireland and Ireland being trialled by Belfast Harbour using its 5G network.
• Queen’s University is harnessing 5G via Building Information Modelling (BIM), Digital Twin technology and AR (Augmented Reality) to support the design and construction of a £100 million, state-of-the-art Advanced Manufacturing Innovation Centre | Queen's University Belfast.

• BT Group trialled the first real-world deployment of 5G Standalone network slicing capabilities over the EE mobile network, launched to support faster and more resilient mobile payments at Belfast’s Christmas Market in 2024. 

  During the two-week trial, a dedicated slice of the EE 5G network was partitioned for use in the renowned Lavery’s Beer Tent to support its eight mobile payment terminals, enabling superfast card and mobile payments for thousands of customers – even during the market’s busiest periods. It marks the first time that a business has benefitted from access to a partitioned slice from EE’s public network and live 5G Standalone core. Learn more at BT Group brings 5G network slicing to Belfast Xmas Market.

• The Belfast 5G Innovation Region (5GIR) Programme led by Belfast City Council’s City Innovation Office, is working with businesses, academia, and the public sector to support the adoption of 5G across the Belfast Region. 5G connectivity is powering digital technologies such as IoT, automation, AI, robotics and immersive technologies which are driving innovation and economic growth across many industries including advanced manufacturing, transport and logistics, creative industries, and public services.  

  Belfast 5GIR is delivering a range of innovative 5G projects and developing resources and plans to ensure that our local businesses and organisations are well-placed to harness advanced wireless connectivity to help grow the economy. NIBUSINESS INFO.CO.UK hosts information on 5G for business.

5G standalone, which has been deployed by some mobile operators in Belfast presents numerous opportunities for all of the public sector in Northern Ireland to improve public services, stimulate economic development, and enhance the quality of life for residents. 

By embracing these opportunities and investing in 5G infrastructure and initiatives, governments can play a key role in shaping the future of their communities. Some of the use cases are:

• Smart Cities Initiatives: Smart city projects aimed at improving infrastructure, transportation, energy efficiency, and public safety can all be enhanced by 5G.
• Enhanced Public Services: 5G enables faster and more reliable communication networks, allowing enhance public services such as healthcare, education, and emergency response.
• Supporting Small Businesses: 5G can enable small businesses to adopt advanced technologies such as augmented reality (AR), virtual reality (VR), and Internet of Things (IoT) applications.
• Tourism and Economic Development: Enhanced connectivity in tourist areas can support augmented reality (AR) experiences and enable innovative digital marketing campaigns.
• Environmental Monitoring: The public sector can use 5G networks to deploy environmental monitoring systems for air quality, water quality, and noise pollution.
• Remote Working and Digital Inclusion: 5G can facilitate remote working initiatives by providing high-speed internet access to rural and remote areas where traditional broadband infrastructure may be lacking.

The current 5G roll out saw MNOs re-use existing sites to install the new infrastructure but to widen coverage further, they also need to install small cells. These can even be on street furniture such as lampposts and benches. For more information on 5G, please see the Commons Library Briefing - 5G in the UK - House of Commons Library.

What is mobile coverage like in NI?

Ofcom’s latest ‘Connected Nations 2025’ report shows that 4G coverage continues to provide the backbone of mobile experience for consumers. Individual MNOs provide good 4G coverage across Northern Ireland, with geographic mobile coverage ranging from 90-96%, depending on the MNO. Outside premises coverage from all four MNOs is available across 97% of Northern Ireland.

There has been a further increase in 5G coverage. Outside premises coverage from at least one MNO now stands at 97% at the High Confidence level and 93% at Very High Confidence, up from 92% and 86% respectively in 2024. Ofcom reports on 5G standalone (5G SA) for the first time this year, and found that outside premises coverage from at least one operator stands at 92% at the High Confidence level and 83% at the Very High Confidence level in Northern Ireland. Coverage figures can mask the disparity between coverage in urban and rural areas. 

A lack of coverage and capacity can lead to dropped calls – when your mobile call unexpectedly cuts off or prevents your device connecting to the internet. Individual operators’ 4G geographic coverage in rural areas ranges from 89-95%, while in urban areas, each operator provides near total coverage. Each network provides a different service and has its own coverage checker. Ofcom also has a coverage checker available to allow consumers to compare mobile coverage in their area across all providers. Mobile Checker - Ofcom.

2G and 3G switch-off

The UK’s mobile networks are gradually retiring their 2G and 3G networks. All of the mobile providers have confirmed that they do not plan to offer their 2G and 3G services beyond 2033, with some operators having already retired their 3G services. By retiring 3G and 2G, these radio frequencies can be repurposed for faster, more energy-efficient 4G and 5G services. 

5G is ten times more energy efficient than 3G and offers customers better, faster and more reliable services. For further information see Switching off the UK’s 2G and 3G mobile networks: what you need to know - Ofcom. Further information is also available at 2G/3G Switch Off - Mobile UK.

How is rural mobile connectivity being improved?

Although improvements are being delivered commercially by the Mobile Network Operators (MNOs), the following interventions have and are assisting with improvements.

The Shared Rural Network (SRN) has now completed locally. Information on the programme can be found at Shared Rural Network (SRN).

The Northern Ireland Barrier Busting Taskforce (NIBBT), the delivery vehicle for the Mobile Action Plan for Northern Ireland (MAP NI), is identifying and addressing the barriers preventing the fast and efficient deployment of mobile connectivity here. Progress updates can be found at MAP NI implementation progress.