Here in the UK, where LTE services are still in their infancy, it feels premature to be looking forward to the fifth generation of mobile networks. However, in recent months there has been a significant increase in activity related to 5G. There has also been a flurry of misleading hype referring to LTE-Advanced (which strictly speaking is the first 4G system) as 5G, but here I am referring to work laying the foundations for the next major evolution in mobile networks.
5G is unlikely to be implemented before 2020 and its precise nature is not yet clear. There is no formal definition of requirements, there are diverse views on the technologies it will embrace, and we are still some way off any standardisation activities. However, the critical importance of another major step forward in capability is unmistakable and significant effort is already being invested into potential solutions.
The International Telecommunication Union (ITU) defined requirements for systems to be regarded as 3G and 4G (as IMT-2000 and IMT-Advanced, respectively) and it is likely to do so again with 5G. While previous requirements have addressed a variety of issues, it was the target data rates that tended to grab the headlines. Data throughput will no doubt be a prominent feature once again, but this time there may be a much stronger focus on other aspects, such as energy efficiency and the user experience.
One thing that is very clear is that radical change of some sort will be essential to keep up with the inexorable growth in mobile data. Traffic is almost doubling annually and even deploying all of the capabilities of LTE-Advanced, networks operating in current mobile spectrum allocations will be facing capacity bottlenecks by the end the decade.
While the details of 5G networks are far from clear, there are certain features that are more than likely to appear. Inevitably there will be further efforts to squeeze even more capacity out of the existing spectrum, including sophisticated multi-antenna arrays and interference mitigation schemes. However, such schemes will only go so far because of physical limits on how much data can be passed through a given bandwidth. Therefore, it will be crucial to develop options for exploiting new radio spectrum. To some extent this may be achieved by releasing further spectrum from other services, such as broadcast TV, and by exploiting more of the lower microwave frequencies (e.g. 2-5GHz). However, it is also likely to require a foray into higher microwave frequencies (above 5GHz) and so-called millimetre wave bands (around 30GHz and upwards). These ranges offer the prospect of very wide bandwidth operation, but their less than favourable propagation characteristics may be a major challenge. A further key to unlocking more capacity will be the deployment of increasingly complex heterogeneous networks comprising radio cells of different sizes, shapes, locations, technologies and spectrum.
Here is a roundup of some of the recent developments related to 5G networks. I look forward to seeing where they take us:
October 2012 – The University of Surrey (UK) was awarded GBP35 million to establish a 5G Innovation Centre to stimulate research, development, innovation and the provision of broadband mobile internet services. The centre will be funded by GBP11.6 million from the UK government (Higher Education Funding Council for England) and around GBP24 million from a group of network operators and equipment manufacturers (Aircom, Fujitsu, Huawei, Rohde and Schwarz, Samsung and Telefónica). The university is already undertaking research into future mobile communication technologies and ultimately the centre is expected to employ 130 researchers and 90 PhD students. Current areas of research include the air interface, cognitive networks and future internet, cognitive radio, radio access system optimisation, security, and knowledge and data engineering.
November 2012 – Even before the completion of its 4G spectrum auction, Ofcom revealed plans to release new mobile spectrum for 5G in the 700MHz band to avoid a “capacity crunch”, as part of harmonised release of 700MHz spectrum internationally. Subsequently, in April 2013, a consultation process was set in progress, to consider the potential release of spectrum from 694MHz to 790MHz and Ofcom hopes can take place by 2018. Ofcom is also considering potential further releases of spectrum at 2.3GHz and 3.5GHz.
November 2012 –The European METIS project (Mobile and wireless communications Enablers for Twenty-twenty (2020) Information Society) began its work. Co-funded by the European Commission, the project is a collaboration of 29 partners, comprising universities, equipment manufacturers, network operators and the automotive industry, with project coordination from Ericsson. With a budget of EUR29 billion (EUR16 billion from the EC) the project will extend 30 months from November 2012 to April 2015. The aim is to provide a European lead in “laying the foundation for the next generation of the mobile and wireless communications system”. Particular areas of interest are network capacity, spectrum utilisation, energy efficiency and cost. The project will study and demonstrate core technologies for 5G, such as new radio link concepts, multi-node/multi-antenna transmission, multi-layer/multi-radio access technology networks and new approaches to spectrum.
April 2013 – The 19th European Wireless Conference (EW 2013), hosted by the University of Surrey, focused on the theme of “5G technologies and Spectrum Crunch in 2020”. The conference covered a variety of technical areas that might have a role in 5G networks, including advanced multi-antenna techniques, cognitive radio, energy efficient techniques and protocols, cooperation, relaying and interference mitigation in heterogeneous networks, millimeter wave communication and much more.
December 2013 – NTT DoCoMo achieved uplink data transmission of more than 10Gbps in drive tests of equipment operating in 400MHz of spectrum in the 11GHz band. The system combined 64-state quadrature amplitude modulation (64QAM), high performance iterative signal processing and decoding (referred to as turbo detection), and multiple-input multiple-output (MIMO) antenna arrays comprising 8 transmitting antennas and 16 receive antennas. The tests were undertaken at little more than walking pace and relied on a vehicle full of equipment. However DoCoMo believes that frequencies above 5GHz will be an important part of the solution for 5G and this technology, which can also be applied at other frequencies, could be an important element of the system.
May 2013 – Samsung announced the results of tests of an adaptive array transceiver technology, which it believes will be an important component of 5G systems. Samsung is of the view that delivering the capacity required by 5G networks will require a move into new regions of the radio spectrum. Previously the Millimetre-wave Ka (26.5–40GHz) band has been considered unsuitable for mobile communications because of its unattractive propagation characteristics (high free space loss, strong atmospheric absorption and severe fading caused by multipath propagation). It has been used at high power levels for line of sight communication, including satellite links, but it has not been suitable for use at the low power levels used by mobile systems. However, operating at 28GHz, Samsung was able to achieve data transmission at 1Gbps over a distance of 2km. The key to this performance was adaptive antenna arrays comprising 64 antenna elements. Samsung aims to commercialise this and other 5G technologies by 2020.
June 2013 – There were presentations and special sessions on 5G at the Global Wireless Summit 2013 (Atlanta City), the LTE World Summit 2013 (Amsterdam) and Mobile Asia Expo 2013 (Shanghai). Among other things there was discussion of the requirements and timing of 5G networks, potential technical solutions and current activities by equipment manufacturers.
July 2013 – Intel announced the creation of an Intel Strategic Research Alliance with leading technology universities, focused on “5G: Transforming the Wireless User Experience”. The work will include studies of new spectrum, improved spectral efficiency and spectral reuse, intelligent use of multiple radio access technologies, and the use of context awareness to improve quality of services and wireless device power efficiency.
July 2013 – The Indian government announced plans for India and Israel to collaborate on 5G standards, development and manufacturing.