5G stands for fifth-generation, and it represents the latest generation of mobile cellular networks that follow the fourth-generation (4G) LTE networks. 5G was introduced in the UK and many other countries in 2019, but it is still in the early stages.
5G stands for the fifth generation of mobile networks and is enabled by the OFDMA-based New Radio (NR) technology. It supports enhanced mobile broadband (eMBB), machine communications (mMTC) and low latency communications (uRLLC) with average download speeds of 150 Mbps and latency of 1 millisecond.
5G is enabled by the New Radio (NR) technology
5G networks use a new air interface powered by the New Radio technology to create wireless connectivity between the cell phone and the 5G network. New Radio, often represented by its acronym NR, was specified in 3GPP release 15 and is based on the same Orthogonal Frequency Division Multiplexing (OFDM) transmission scheme as the 4G LTE networks.
5G networks use a new radio interface enabled by the New Radio (NR) technology. NR is OFDMA-based, and it can operate at various frequency bands, including 20-90 GHz (high band), below 6 GHz (mid-band) and sub-1 GHz (low band). 5G networks can be deployed as standalone (SA) or non-standalone (NSA).
The New Radio (NR) technology provides a 5G migration path to all 4G LTE cellular networks worldwide, irrespective of which 2G or 3G technologies they use. 5G can enable peak download speeds of around 10 to 20 Gbps; however, the average speeds are considerably lower. Unlike earlier cellular technologies that only focused on mobile phones, tablets, and low-bandwidth IoT devices, 5G NR technology has a very flexible approach to addressing a variety of use cases within the consumer and enterprise segments. The focus in 5G is the varying levels of data rates and latencies that the network can support to enable a wide range of use cases within many industries.
5G NR employs a flexible and wide-ranging frequency spectrum, advanced MIMO antenna technology, network slicing for network virtualisation, dual-connectivity for co-existence with 4G LTE, and reduced latency through edge computing to bring content closer to users.
What 5G NR network looks like
Like any other mobile network, the 5G mobile network consists of a radio, transport, and core network. The transport network connects the radio network to the core network. The radio network in 5G consists of the cell tower, gNodeB or gNB, which stands for Next Generation Node B. The gNB may be split into gNB central unit (CU) and the gNB distribution unit (DU).
The Distribution Unit or DU is responsible for real-time scheduling functions, i.e. which device should communicate when and what radio resources (e.g. frequency, time slot etc.) to assign to which device. The Central Unit deals with non-real-time functions.
CU works with the higher layers of the network protocol stack, whereas DU works with lower layers of the network protocol stack, such as PHY, MAC and RLC. The DU is closer to the site, whereas the CU, as the name suggests, can be at a central location.
The 5G core network consists of several nodes, which you can see in the diagram below. Generally, the nodes you are most likely to see in simplified network diagrams are AMF and UPF. UPF is the User Plane Function, and AMF is the Access & Mobility Management Function.
| # | 5G Core Network Function (Acronym) | Explanation |
|---|---|---|
| 1 | UPF | User Plane Function |
| 2 | AMF | Access & Mobility Function |
| 3 | SMF | Session Management Function |
| 4 | AUSF | Authentication Server Function |
| 5 | NSSF | Network Slicing Selection Function |
| 6 | NEF | Network Exposure Function |
| 7 | NRF | NR Repository Function |
| 8 | UDM | Unified Data Management |
| 9 | UDR | Unified Data Repository |
| 10 | AF | Application Function |
| 11 | PCF | Policy Control Function |
What use cases can 5G networks enable?
While the earlier mobile networks primarily focused on voice calls, text messages and high-speed mobile internet, 5G networks have a broader focus where technology development is based on three key use case categories. These categories are Enhanced Mobile Broadband (eMBB), Massive Machine Type Communication (mMTC) and Ultra-Reliable Low Latency Communication (uRLLC).
eMBB or Enhanced Mobile Broadband (or Extreme Mobile Broadband) is all about high-speed mobile internet. It can enable peak data rates of over 10 Gbps; however, the average data rates are considerably lower. eMBB is one of the earliest use cases of 5G, which we can all relate to. For a customer, it is the next best thing after 4G LTE Advanced Pro networks that offer peak data rates of up to 3 Gbps (average around 60-80 Mbps). However, in real-life, 5G networks can already offer average download speeds of around 150 to 200 Mbps. Examples here include 5G broadband routers and 5G mobile hotspots.
mMTC, or Massive Machine Type Communication, as the name suggests, focuses on machine-to-machine (M2M) communication to support Internet of Things (IoT) use cases. With mMTC, the requirement for 5G networks is to support 1 million devices per square kilometre. To support this massive number of device deployments in a practical way, it is necessary that devices are low maintenance and can stay unattended for long periods of time. 5G networks, therefore, require that these devices consume very little power so that the batteries can last for up to ten (10) years. Examples of mMTC include home automation, sensors, actuators etc.
uRLLC or Ultra-Reliable Low Latency Communication focuses on enabling connections that have a reliability factor of 99.99% and latencies of below one millisecond (1 ms). This category is for mission-critical applications where the data transmission requires low bit rates, but the communication link is expected to be guaranteed. An example includes self-driving cars, where control information is required to control the car functions remotely in real-time.
I have written a dedicated post on eMBB, mMTC and uRLLC that dives into the details of these use case classes.
Standalone and non-standalone 5G deployments (NSA and SA)
5G NR mobile networks can be deployed in two ways: standalone 5G and non-standalone 5G. Standalone 5G or SA is an end-to-end 5G network that includes a 5G radio network and a 5G core network; a non-standalone 5G network has a 5G radio network, but it utilises the existing 4G core network (EPC).
A non-standalone 5G network or NSA deployment model requires a 5G radio access network to work with an existing 4G LTE core network (Evolved Packet Core – EPC). The NSA deployment model uses the 4G LTE network for control plane functions such as signalling. The user plane is responsible for the size of the data pipe for the content delivery and uses both 4G and 5G base stations.
The standalone version of 5G or SA is an end-to-end 5G NR network with a 5G radio access network and a 5G cloud-native core network. The 5G core network follows a Service-Based Architecture (SBA), where the network works in a virtualised way by making the resources available depending on the services being delivered. The technique that makes it happen is called Network Slicing, which is explained below.
As far as the radio network is concerned, there are two types of radio base stations (cell towers) used in 5G NR networks: gNodeB (next-generation Node B) and ng-eNodeB (next-generation evolved Node B). gNodeB is the 5G base station that connects 5G cellular devices (e.g. 5G cell phones) to the mobile network. In network deployments with a 5G cloud-native core network (5GCN) for both 4G LTE and 5G NR mobile devices, ng-eNodeB (ng-eNB) is the base station that allows 4G LTE devices to connect to the network.
I have written a detailed post on Standalone and Non-Standalone 5G networks with diagrams to help you visualise the concept.
Futuristic use cases through Network Slicing in 5G
The full potential of 5G can only be achieved through the standalone deployment of 5G (SA), which is an end-to-end 5G network. The two essential network components required for that are the 5G next-generation radio access network (NG-RAN) and the 5G cloud-native core network (5G CN).
Network slicing in 5G New Radio allows the core network to create multiple virtual networks within the existing physical infrastructure by applying changes virtually rather than physically. This is enabled by the Service Based Architecture (SBA) of the 5G core network that allocates network resources based on the use cases or services in question. For example, it is possible that one network slice provides connectivity to mobile broadband users with a focus on high-speed data rates, whereas another slice can focus on connectivity to self-driving cars where lower latencies are reliable with high levels of reliability.
5G core network can accommodate a number of different slices to address a wide range of use cases with varying levels of Quality of Service (QoS) requirements. For example, communication services in healthcare, mobile broadband, smart cities, connected cars etc., may have different requirements in terms of data rates, latency, mobility and reliability. It is important to note that one user device (e.g. a mobile phone) can be connected to multiple network slices at any given time; however, the control and signalling information is communicated through one slice at a time.
The 5G core network components, including Network Slice Selection Function (NSSF) and Access and Mobility Management Function (AMF), work together to enable network slicing in 5G. The 5G radio network works alongside the 5G core network to allocate radio network resources as needed. Please look at this dedicated post on 5G network slicing that provides more details on the topic.
5G NR networks can use FDD or TDD duplexing schemes
The 5G New Radio (NR) technology can operate in both Frequency Division Duplex (FDD) and Time Division Duplex (TDD). The radio frame structure of 5G New Radio technology is designed to support both half-duplex and full-duplex communication.
FDD is a full-duplex system providing simultaneous communication in both directions. TDD is technically half-duplex but can offer concurrent two-way communication that emulates full-duplex communication. FDD uses a pair of frequency bands, one for uplink and one for downlink. On the other hand, TDD can use the same band for uplink and downlink but at different timeslots. TDD is suitable for higher frequencies in 5G because those bands are mainly used in smaller areas where fewer base stations are required to minimise interference.
5G NR networks use the OFDM transmission scheme
5G New Radio (NR) technology employs the Orthogonal Frequency Division Multiplexing (OFDM) transmission scheme, which is also used by the 4G LTE networks. 5G networks use the multiple access technique, Orthogonal Frequency Division Multiple Access (OFDMA), for both downlink and uplink communication.
In 4G LTE networks, the sub-channel spacing is 15 kHz, but 5G NR is more flexible and can use sub-carrier spacing in the multiples of 15 kHz, e.g. 30 kHz, 60 kHz etc. From a bandwidth perspective, LTE uses a maximum carrier bandwidth of 20 MHz, and through carrier aggregation, it can combine up to 32 carriers to achieve a maximum bandwidth of 640 MHz (32 x 20 MHz) in LTE Advanced Pro. In 5G NR, the maximum channel bandwidth is 400 MHz; with multiple carriers, 5G can use up to 16 carriers. That allows the maximum bandwidth to be 400 MHz x 16 = 6400 MHz or 6.4 GHz. Higher bandwidth leads to higher data speeds, allowing 5G to offer much higher speeds than 4G LTE networks.
Frequency spectrum for 5G NR and millimetre waves
One of the primary enablers for flexibility and scalability in 5G networks is the flexible use of the radio frequency spectrum. 5G networks are not limited to a single frequency band and are designed to operate in frequency bands ranging from 400 MHz to 90 GHz. They support both licensed and unlicensed frequency bands and can work in FDD (Frequency Division Duplex) and TDD (Time Division Duplex). According to this web page on GSMA’s website, 5G spectrum guide, the majority of commercial 5G launches rely on the 3.3-4.2 GHz frequency range. In the UK, for example, all mobile operators currently use the 3.4-3.6 GHz band for 5G, which falls in the mid-band range.
Have a look at the table below to see the range of frequency bands supported by 5G NR and the peak data rates. Please note that peak data rates outline the theoretical maximum rates which are considerably higher than the average rates we get in real life.
| Frequency range | Peak data rates | |
|---|---|---|
| High band (Millimetre waves) | 20 GHz to 90 GHz | 5 to 20 Gbps |
| Mid band | < 6 GHz | 2 Gbps |
| Low band | < 1 GHz | 200 Mbps |
According to the laws of physics, radio waves experience higher losses when they travel at higher frequencies and experience lower levels of losses when they travel at lower frequencies. Lower frequencies can support lower bit rates but travel longer distances than higher frequencies. The lower frequency band for wide-area 5G coverage in Europe is the 700 MHz band. The equivalent in the US is the 600 MHz band. Higher frequency bands can accommodate bigger channels with lower latency levels.
Generally, 30 GHz to 300 GHz frequency bands are called millimetre waves in telecommunications because each wave in this frequency range has a wavelength of between 1 and 10 millimetres. In 5G NR networks, the frequency bands between 20 GHz and 90 GHz are considered millimetre waves.
Millimetre waves, abbreviated as mmWaves, have high capacity (bandwidth), low latencies (~1 ms) and limited range, making them suitable for providing extremely high-speed broadband services in fixed locations using a small cell deployment model.
This fixed location deployment is generally referred to as Fixed Wireless Access (FWA). In addition, as mmWaves support low latencies, they are an ideal solution for the gaming and manufacturing industries.
Dynamic Spectrum Sharing (DSS) in 4G and 5G networks
Since 5G New Radio (NR) technology supports a very broad frequency spectrum, it is able to operate at frequencies currently used by 4G LTE networks. This is where the Dynamic Spectrum Sharing (DSS) technique comes in. Dynamic Spectrum Sharing allows a cell to dynamically assign its full bandwidth to 4G LTE or 5G NR depending on which customer device needs connectivity.
For example, if a base station (cell tower) has a channel with a bandwidth of 20 MHz, it can allocate all of the 20 MHz to support a 4G LTE phone or a 5G NR phone, depending on which device is trying to connect. DSS can schedule the allocation of bandwidth depending on customer demand. DSS allows mobile operators to launch 5G services on existing 4G LTE frequencies, saving them time and money. I have written a dedicated post on Dynamic Spectrum Sharing (DSS), which dives into the details of how DSS works.
Massive MIMO and multi-user MIMO antenna technologies in 5G
MIMO, or Multiple Input Multiple Output technology, was first introduced in mobile networks in HSPA+ or Evolved High-Speed Packet Access. The requirements for the HSPA+ enhancement were specified in 3GPP release 7. 4G LTE networks took the MIMO technology to another level with various antenna configurations in LTE, LTE Advanced and LTE Advanced Pro networks. The MIMO technology has also been a requirement for the Gigabit LTE milestone, which is often talked about in the context of 5G networks.
5G New Radio networks use an advanced version of MIMO called Massive MIMO, which employs a large number of antenna elements at the transmitter and the receiver. Massive MIMO also supports the multi-user MIMO technique, allowing the transmitter and receiver antenna elements to support multiple users simultaneously. MIMO in 4G LTE networks uses a maximum antenna configuration of 8 x 8 for the downlink, which means the 4G network supports a maximum of eight (8) communication layers for download purposes. In 5G Massive MIMO, the antenna configuration can be in tens or even hundreds. For example, mobile network vendors already offer 5G antennas with a MIMO configuration of 64 x 64, but 256 x 256 is also possible. However, the purpose of MIMO in 5G is not just data rate and radio link quality enhancements but also capacity improvements. The capacity improvement is achieved through Multi-User MIMO, which allows the 5G base stations (gNodeB) to support multiple users simultaneously.
Beamforming in 5G Massive MIMO
While MIMO technology benefits from various building blocks, including spatial multiplexing and diversity, beamforming is one of the key benefits of MIMO antennas.
Beamforming is a capability in advanced antenna systems that allows the different antenna elements of a MIMO antenna panel to concentrate the signal transmission in a particular direction. Beamforming shapes the radio signals coming out of the antennas in such a way that instead of travelling in various directions, they target specific user devices.
Furthermore, 5G NR networks use three-dimensional beamforming, which means the beams can be horizontal and vertical to support multiple simultaneous users. I have written a dedicated post on 5G Massive MIMO that goes into the details of beamforming and its benefits for 5G NR.
Download and upload speeds for 5G networks
As most 5G deployments currently use the non-standalone 5G model, 5G networks are yet to reach their full potential. The peak download speed of 5G networks is between 10 Gbps and 20 Gbps, with a latency of as low as one millisecond. The peak speeds are theoretical and represent the maximum throughput potential of the network. In real life, we get average speeds that are considerably lower than peak speeds.
On average, 5G networks can achieve download speeds of around 150 Mbps and upload speeds of approximately 30 Mbps in an indoor set-up. In outdoor environments, especially when closer to a base station, you can expect to see download speeds of up to 400 Mbps or higher. Of course, all data speeds depend on how your mobile network operator (MNO) is serving a specific geographical location.
Have a look at this dedicated post on average 5G download and upload speeds to get a comprehensive view of 5G data rates based on speed tests carried out in the UK.
Voice calls in 5G can use Voice over NR (VoNR) or VoLTE
Like the fourth-generation (4G) LTE networks, 5G New Radio (NR) networks are also packet-switched and deliver all services over the IP network. In 4G LTE networks, voice calls, and text messages (SMS – Short Message Service) are delivered by Voice over LTE (VoLTE) technology.
The equivalent of VoLTE in 5G NR networks is Voice over New Radio (VoNR). Like VoLTE, VoNR requires the mobile core network to work alongside the IP Multimedia Subsystem (IMS) to enable IP-based voice calls can messaging. Voice over NR (VoNR) requires a 5G cloud-native core network (5GCN) to work with IMS and is a solution for standalone 5G.
The non-standalone 5G deployments use a 4G LTE core network (Evolved Packet Core – EPC), allowing 5G networks to benefit from the Voice over LTE (VoLTE) technology for voice calls and text messages. Check out our dedicated post on VoLTE, VoNR and Wi-Fi calling to learn how VoLTE and VoNR work in mobile networks.
Phone and SIM requirements for accessing 5G networks
If you want to access the 5G network from your phone, you need a 5G-compatible cell phone. Your 4G phone is based on LTE technology, which differs from 5G New Radio (NR). Generally, your existing 4G SIM card should work in your 5G phone to enable 5G access. If you currently have a 4G LTE phone and are considering buying a 5G phone, check out this dedicated post on a 5G phone and SIM card.
All cellular technologies are backwards compatible; therefore, the 5G NR phone will also allow you to access the 4G LTE network. If you already have a phone and are unsure whether it is a 4G or 5G phone, look at this post to find out if your phone supports the 5G NR technology.
Download the FULL version of our 5G Overview slide deck, which provides a comprehensive overview of 5G NR networks.
Download the FREE version of our 5G overview slide deck, which provides a basic overview of 5G NR networks.
