5G can be pictured to consist of three spearheads. The first one is the enhanced mobile broadband, which offers peak data rates of several gigabits per second. The second spearhead is related to the Internet of Things or massive machine type communications. The third one is critical communications, which requires ultra-reliable and low latency communications.
The key technical goals for the 5G network are related to low latency, increased data rate, network capacity in relation to throughput and terminal density, mobility, and the energy and spectral efficiency of the network.
5G has not been designed for interpersonal communications only, but also for device-to-device communications. Therefore, it will provide new business opportunities for various sectors. In the health sector, 5G enables, for example, intelligent remote monitoring or wireless flexible media production and sharing. Future factories can use 5G for such purposes as plant automation and intelligent robots. In the future, it will play an important role in energy production and distribution and their management. And what would intelligent transport be like without 5G connections?
Technologies enabling 5G
New technologies also enable the optimisation of the entire communications network. The most significant among such reforms include programmability of the communications network and virtualisation of functions. This enables implementation and scaling of network functions by means of virtualisation without heavy investments in hardware. This will also expedite the proliferation of new services, because a virtualised technology network can be dynamically adapted according to existing needs. Programmable routing allows introduction of new solutions for managing the increasing amounts of data and guaranteeing improved service for users. Services can also be implemented increasingly closer to users at the edge of the network.
Network programmability and function virtualisation technologies also enable the development of new optimisation mechanisms, such as network slicing. That can be used for implementing several separate functional entities and resource allocation in networks on the basis of different service requirements, such as quality of service or data security. When combined with software-based routing of data, new faster 5G radio solutions and services implemented at the edge of the network allow achievement of an ultrafast and almost zero latency communications network.
Of course, 5G does not transform the laws of physics, but major steps towards fully digitised and at least partly virtualised society can be expected. Companies processing large amounts of data and major data flows, such as Facebook and Google, are trailblazers in the utilisation of these network technologies, and they have already introduced such solutions to widespread use.
Typical features of the 5G system include small cells, the introduction of millimetre wavelengths and massive antenna arrays. Major problems, on the other hand, include high energy consumption, attenuation of radio waves and interference. Radio waves spread in all directions, and only a small share of the power transmitted reaches the receiver, which causes attenuation. Antenna arrays can be used for adaptive beamforming at base stations, which allows transmitting the power in exactly the right direction.
Since the bit rates and carrier wave frequencies used are high, the range between links becomes shorter and the cells become smaller than previously. The highest bit rates (20 Gbit/s) may only be reached at the range of a few dozen metres, because the transmit power must be controlled for safety reasons. The computing functions must also be sufficiently simple to avoid excessive power consumption due to cooling problems. The modulation methods to be used will probably be almost the same as in the earlier LTE system (LTE = Long Term Evolution). The system currently in use is the orthogonal frequency division multiplexing (OFDM) scheme and its variations. On the
other hand, there will be changes in the channel coding techniques. New, improved codes will come to use, and, in the same way as before, there will be separate codes for data and control channels.
Low latency is substantial in various control applications, since delays slow down the control action and cause instability. One control application for the 5G system is tactile, or haptic, communications in addition to the traditional audio-visual communications. Tactile communications are based on the sense of touch, as an example of which we can mention remote control of a machine by means of human sight and sense of touch. Haptic communications is a slightly wider concept, including the sense of motion in addition to the sense of touch.
If the time delay between what is seen and felt is more than 1 ms, people usually start feeling sick. This phenomenon is called cybersickness. Due to network latency, tactile communications can not be successfully achieved over ranges exceeding a few kilometres.
Figure 1. ITU-R’s IMT-2020, or 5G, use scenarios (ITU-R = International Telecommunication Union
- Radiocommunication Sector, IMT = International Mobile Telecommunications), which the three
5G spearheads specified above meet, and the key vertical sectors utilising 5G as presented by 5G PPP (5G Infrastructure Public Private Partnership).
High frequencies to use
Due to the need for high data transfer capacity, new frequencies will be neede to ensure the availability of a sufficiently large bandwidth.
So far, the frequency bands used have usually been below 6 GHz. The globally agreed frequency bands for 5G systems are 694–790 MHz, 1427–1518 MHz (L-Band) and part of the band 3.4–3.6 GHz (C-Band). Some countries will use other frequencies as well, the highest ones being in the range of 4.8–4.99 GHz. Frequencies within the range 24.25–86 GHz have also been planned for 5G systems, but it will take a few more years before decisions on the matter are made.
Frequencies above 30 GHz are called the millimetre waves, since their wavelength is 1–10 mm. Frequencies above 10 GHz are prone to weather phenomena (rain causes additional attenuation), and atmospheric attenuation affects them more than lower frequencies. On the other hand, millimetre waves enable the use of relatively small-sized antenna arrays, which allows increasing the antenna gain.
In any case, the range between links will become shorter, maybe approximately 200 metres at the most. This creates a need to use adaptive algorithms, since the beam needs to be steered in the right direction. This, on the hand, increases complexity and power consumption, and the use of antenna arrays is usually limited to base stations.
Figure 2. Overview of 5G standardisation, first 5G demonstration events and EU project opportunities
(3GPP = 3rd Generation Partnership Project, WRC = World Radio Congress).
5G as an accelerator of the Internet of Things
The Internet is on its way to almost all objects, for example, at homes and industrial environments. The Internet of Things must often function indoors, where different obstacles cause additional signal attenuation. The data produced by sensors must be available for the users. At most, there can be a million different sensors per square kilometre, and therefore low power consumption is an important requirement. For example, in microsensors the power consumption should not exceed 0.1 mW.
Usually, the amount of data being transferred is relatively small, and it is transferred seldom and irregularly. The sensors must be inexpensive and battery-powered, and their replacement interval must be up to 10–15 years. This requires limitations on complexity and bit rate (e.g. 10 kbit/s), use of power saving modes and collection of energy from the surroundings. In a way, the sensors are put to sleep and activated only when needed. This is significant also with regard to interference. When operating at power levels not exceeding 0.1 mW, it may be necessary to limit the link ranges to a few metres. At higher link ranges, the power level would need to be increased.
5G brings new services
The technical advances brought by the 5G network, such as very rapid network response time and ultra rapid wireless connections, enable implementation of novel services. The scientific and industrial research community is seeking new opportunities for applications in automotive industry, eHealth, different factory environments and entertainment use for individual users.
In entertainment use, different virtual applications, and transmission and reception systems of top-quality video image make novel experiences that feel increasingly realistic available to users. In the automotive industry, the most potential 5G technology users are self-driving cars and various systems that improve traffic safety, such as automatic warnings about slippery roads or other unexpected hazards. In the eHealth sector, on-line doctor services in real time or procedures performed from a distance also pose a very big challenge to the data network latency in particular – the very same issue the new 5G technologies also strive to address.
Another common feature in all new services is their energy efficiency goal, which the developers seek to solve by means of smart electrical grid solutions. Such a system would include the entire energy efficient entity from power generation facilities and transmission of electricity to the Internet of Things and electric cars.
Test networks as accelerators of 5G development in Finland
The 5G Test Network Finland project (5GTNF, 5gtnf.fi), coordinated by VTT and mostly funded by Tekes, functions as an innovation platform that supports the R&D work performed by companies and research institutes. It offers an open and versatile test platform for 5G technologies distributed around Finland, and the testing and development of relevant services, applications, algorithms and systems before the 5G system becomes commercially available. Dozens of cooperation partners form a comprehensive ecosystem, which is capable of catering for a wide variety of needs that SMEs, industrial sector businesses in their early phases and research institutes may have.
At the moment, the 5G test network projects are increasingly directed towards vertical operators taking advantage of 5G. There are already several operators representing vertical sectors involved in these projects, developing and testing new business opportunities offered by 5G technology.
DSc (Technology) Atso Hekkala works as Senior Scientist in VTT’s Connectivity Research Area. His research interest is focused on signal processing solutions related to 5G systems. Currently, he acts as coordinator of the 5G test network project (5gtn.fi).
Principal Scientist, PhD Jukka Mäkelä works in VTT’s Connectivity Research Area. In his current research, he focuses on future communications networks, including 5G. He is also involved in the development of future communications solutions for the needs of the Internet of Things and the Industrial Internet.
DSc (Technology) Aarne Mämmelä acts as Research Professor at VTT’s Oulu Unit.
His area of research is digital signal processing in wireless communications. He is also
interested in intelligent resource-efficient systems, systems thinking and the history of technology.
Photos: VTT, Sandrine Boumard
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