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Traveling Wave Tube based W-band Wireless Networks with High Data Rate, Distribution, Spectrum and Energy Efficiency

Periodic Reporting for period 3 - TWEETHER (Traveling Wave Tube based W-band Wireless Networks with High Data Rate, Distribution, Spectrum and Energy Efficiency)

Reporting period: 2017-01-01 to 2018-09-30

The limitless diffusion of portable smart devices with very high-resolution screens, of new data hungry applications and the future Internet of Things (IoT) that predicts billions of devices connected is opening a new age for internet high speed connections every time and everywhere.
Most of the data traffic is predicted to be wireless, but no existing wireless network at microwave frequency can actually sustain the dimension of the future data flux. The microwave spectrum is already congested and the available band are too narrow to support a multigigabit data rate.
Two main challenges have to be solved. One is related to the new generation of mobile networks to enable 5G. A high data rate at terminal level, maintaining the transmission at microwave range, can be achieved reducing the radius of a cell and increasing their density. This needs high capacity backhaul to feed a high density small cell networks in flexible and affordable manner.
The second challenge is the digital divide that severely affects low density inhabitant areas, namely rural and suburban, where fiber could not be deployed both for high costs and environmental constraints.
Millimeter waves have been unanimously recognised as the new technological frontier in wireless communications. Very wide frequency bands are available in different portions of the millimeter wave spectrum (60 GHz, 70-85 GHz, 92 -95 GHz and above), that could permit high capacity transmission.
Point to point (PtP) millimetre wave wireless links are already available, but when the number of links increases, PtP is not convenient due to frequency plan and deployment flexibility. The point to multipoint distribution (PmP) has the advantage to cover a wide area without frequency plan, with low footprint and arbitrary distribution of terminals. The transmission hub uses a low gain antenna that needs high transmission power to achieve a useful range. No amplifier was available to enable point to multipoint at millimetre wave above 40 GHz, because of the higher atmospheric attenuation and raining attenuation that require multiwatt power level.
The H2020 TWEETHER project introduces a new concept of wireless networks at millimeter wave enabled by a novel wireless point to multipoint distribution at W-band (92 – 95 GHz).
The TWEETHER consortium is simultaneously addressing a number of formidable challenges to build the first PmP at W-band to overcome the atmosphere attenuation by a novel high power Traveling Wave Tube (TWT)amplifier in the transmission hub. In addition, a full system at W-band is designed and build including a sophisticate synchronisation, a novel W-band MMIC integrated circuits. The target is enabling a new deployment scenarios, low cost approach, and the transfer of niche technology to a mass production.
In addition, the W-band has the great advantage to be lightly regulated for PmP distribution.
The breakthrough of the W-band TWEETHER system is making the PmP distribution possible at millimetre wave with up to 3.5 Gbps/km2 of area capacity over a few kilometres square.
TWEETHER is a challenging project carried out by three main parallel routes converging to the final field test in real environment of the W-band PmP system.
One route is on the definition of the system specifications, on the scenario evaluation for the best TWEETHER system deployment and the achievable performance, and, finally on the market perspectives and economic and social impact.
It has been demonstrated that for both backhaul of small cells and access (backhaul of LTE 3.5GHz) the transmission hub could cover a circular region of a few km square with up to 3.5 Gbps/km2.
This result is a step change in wireless networking that will reshape the concept of wireless Internet distribution, removing the needs of fiber for high speed internet.
The second route of the project is on the design and fabrication of the first Traveling Wave Tube to produce transmission power higher than 40 W at W-band. A first prototype has been fabricated and tested, a second improved prototype is under fabrication.
The third route is on the design and fabrication of the low power modules. It includes a highly stable and very low phase noise Ku synthesiser, the W-band MMIC chip set, and the antennas. The MMIC chip set includes a low noise amplifier, the 8x multiplier, the down-converter, the up-converter and the power amplifier. A new GaN process for the power amplifier has been also performed at the end of the project with promising results for extending the range of terminals.
A low gain horn antenna for the transmission hub and a high gain lens antenna for the terminal were built and tested.
Two System in Package (SIP) for transmission and reception were assembled and allocated in motherboards including the synthesisers and the connection to the modems to be assembled in the transmission hub ant terminal.
A setup including one transmission hub and three terminals has been deployed at UPV for the first field trial at world level of a W-band point to multipoint wireless system.
The TWEETHER concept will project the actual wireless networks above the threshold of the microwave, providing high capacity for the new 5G heterogeneous small cells and to solve the digital divide in residential and rural areas with high speed connections.
The novelty of the approach including a TWT of new design in a transceiver at W-band, is itself a progress beyond the state of the art.
The advances in W-band technology introduced by the TWEETHER project will boost the European millimeter wave industry, speeding up the deployment of innovative products suitable not only the wireless economy sector, but also for other telecommunication systems or applications such as high resolution radar and imaging.
The economic impact is for the component market at millimetre wave and at level of wireless networks for dynamically distributing in a cost-effective manner multi-gigabit capacity to a number of small cells or residential access points.
High-speed broadband networks, as TWEETHER, are recognized as a catalyst for social and economic development and will therefore have a strong socio-economic impact.
New large markets will be created. For example, in health care alone it is expected that 500 million people will use mobile applications or IoT (internet of things) will extend and multiply connections between objects of mass use (e.g. connected car and appliances) and of industrial infrastructure (Industry 4.0) reaching billions of additional connections. With data rate requirements steadily increasing, the use of W-band is mandatory for delivering broadband services to end users everywhere. W-band communication technology is the key enabler for high speed internet everytime and everywhere for future-proof way of living, allowing home working, e-health and e-government, and other e-services by last mile complement of the fibre.
The following progress beyond the state of the art have been produced:
GaAs W-band chip set including low noise amplifier, downconverter and upconverter, 8x multiplier and power amplifier.
A first prototype of GaN power amplifier
First W-band TWT
System in Package transmitters and receivers and Motherboards
W-band transmission hub and terminals
New wireless network paradigm for point to point at W-band with high capacity.
First TWT prototype
TWEETHET Transmission Hub Deployed at UPV for the field test
TWEETHER Terminal Deployed at UPV for the field test
Folded Waveguide Half structure
TWT beam stick
Figure for PmP
Field trial
Transmission Hub