• Field trials in France of 6Ghz to 100GHz cellular
• Essential component of future 5G systems
• Part of the 5G-PPP mmMagic project
• Role of microwave becoming increasingly important

It’s magic, as the great Paul Daniels, TV magician par excellence was wont to say. The idea that within a decade our cellular networks will be operating at the stratospherically high frequencies of 300GHz sounds impossible – after all, today’s technology uses frequencies from 450MHz to 2.7GHz (up to 3.7GHz in some isolated TDD cases). 2.7GHz is considered high frequency by today’s standards. The thought of being able to operate 5G networks with bands above 6GHz and up to an incredible 100GHz – with their ever shorter wavelengths (remember, fellow physicists, wavelength is inversely proportional to frequency) – is the stuff of magic.

Rather appropriate then that Europe’s 5G-PPP public-private partnership organisation has called its microwave wavelength project “mmMagic”. In this case, Magic is a slightly contrived acronym Mobile Radio Access Network for Fifth Generation Integrated Communications – a research project to develop and design new concepts for mobile RAT for mmW deployment, and a key component in the 5G multi-RAT ecosystem that is envisaged.

The project brings together infrastructure vendors (Samsung, Ericsson, Alcatel-Lucent, Huawei, Intel, Nokia), operators (Orange and Telefonica), research institutes (including the technical university of Dresden) and measurement equipment vendors (such as Rohde & Schwarz). An Advisory Board of telecoms regulators from Germany, France, Finland, Sweden and the UK will oversea the project and provide guidance.

This week, the French regulator ARCEP issued Orange with an authorisation to conduct mmMagic project trials in the city of Belfort, France, up to the end of 2016. It’s part of a larger initiative being undertaken by ARCEP to stimulate innovation, and since January this year it has issued 75 authorisations to use frequencies for trials and experiments.

Orange and the mmMagic partners intend to examine the conditions of use for mmW frequency bands between 6GHz and 100GHz for future 5G deployments. And this is not as easy as it might appear. Propagation characteristics of incredibly short mm-wavelengths are totally different than for the UHF wavelengths used today, and especially affect how signals travel through walls and windows, and bounce off objects and buildings. Whilst mmWs give rise to massively improved bandwidth (also helped via techniques such as beamforming and antenna arrays), network planning will have to be rethought.

Hence the need for real-world trials and computer modelling. The proposed new radio interface for mmW-based 5G networks will need to use adaptive and cooperative beamforming and tracking techniques to address the specific challenges of mmW propagation.

Recent work on mmW in New York City at 28GHz and 73GHz, and reported by the IEEE, showed that mmW systems could offer more than an order of magnitude increase in capacity over LTE networks at current cell densities, and operate well at distances of up to 200 metres from a low-power microcell – even in the “urban canyon” environment of New York City.

The IEEE concurs that mmW 5G cellular systems will need to be significantly redesigned to fully achieve these gains: “Specifically, the requirement of highly directional and adaptive transmissions, directional isolation between links, and significant possibilities of outage have strong implications on multiple access, channel structure, synchronisation, and receiver design”.

The trials in France are just one part of a global effort to realise the potential of 5G. The mmMagic project, which will run for two years, will undertake extensive radio channel measurements in the 6-100GHz range, and will develop and validate advanced channel models that will be used for validation and feasibility analysis of the proposed concepts and system, as well as for use in regulatory and standards bodies. The goal of the project is to give Europe a lead in the development of 5G standards, and of course to secure highly-prized essential IPRs for European vendors.

Whilst we should expect the first 5G networks to be commercially operational by 2020, mmW-based networks are unlikely to appear for at least five years after that.

Meanwhile, a report released this week from Ericsson predicts that by 2020 microwave technology will support multi-gigabit capacities in traditional frequency bands, and support over 10GB in the millimeter wave (E and V) bands. It believes E band spectrum will be key in catering for capacity increases in backhaul as well as fronthaul.

“Microwave networks are a vital ingredient for operators to provide the best possible performance and quality of experience in the most cost-efficient way, and will continue to be the dominant backhaul technology in the future,” said Karolina Wikander, Head of Microwave at Ericsson. “Capacity needs will continue to increase on the road to 5G, and keeping up requires continued technology evolution and re-imagining network efficiency.”

Ericsson foresees that in the coming years microwave will continue to be the dominant backhaul technology, and that by 2020, 65 per cent of all cell sites will be connected by microwave solutions (although markets such as China, Japan, South Korea and Taiwan that have existing deep fibre investments will be the exception). The choice between fibre and microwave in backhaul networks will no longer be about capacity, but about fibre presence and total cost of ownership calculations.

Ericsson believes a seven-time capacity increase can be achieved using a wide, low-availability link in the E band (70-80GHz) to boost a high-availability link in traditional bands. As such, E band usage will experience major growth and will represent up to 20 per cent of new deployments in 2020.