Scientists propose data encoding method for the 6G standard

https://phys.org/news/2020-06-scientists-encoding-method-6g-standard.html

Researchers around the world are working on methods to transfer data in the terahertz (THz) range, which would make it possible to send and receive information more quickly than today's technology. But it is much more difficult to encode data in the THz range than in the GHz range currently used by 5G technology. A group of scientists from ITMO University has demonstrated the possibility of modifying terahertz pulses in order to use them for data transmission. They have published their results in Scientific Reports.

Telecommunications companies in advanced economies are beginning to adopt the new 5G standard, which will provide previously impossible wireless data transfer speeds. Meanwhile, as companies roll out this new generation of data networks, scientists are already at work on its successor. "We're talking about 6G technologies," says Egor Oparin, a staff member of ITMO University's Laboratory of Femtosecond Optics and Femtotechnologies. "They will increase data transfer speeds by anywhere from 100 to 1,000 times, but implementing them will require us to switch to the terahertz range."

Today, a technology for simultaneous transfer of multiple data channels over a single physical channel has been successfully implemented in the infrared (IR) range. This technology is based on the interaction between two broadband IR pulses with a bandwidth measured in tens of nanometers. In the terahertz range, the bandwidth of such pulses would be much larger—and so, in turn, would be their capacity for data transfer.

But scientists and engineers will need to find solutions to numerous crucial issues. One such issue has to do with ensuring the interference of two pulses, which would result in a so-called pulse train, or frequency comb, used to encode data.

Egor Oparin, a staff member of ITMO University's Laboratory of Femtosecond Optics and Femtotechnologi

"In the terahertz range, pulses tend to contain a small number of field oscillations; literally one or two per pulse," says Egor Oparin. "They are very short and look like thin peaks on a graph. It is quite challenging to achieve interference between such pulses, as they are difficult to overlap."

A team of scientists at ITMO University has suggested extending the pulse in time so that it would last several times longer but still be measured in picoseconds. In this case, the frequencies within a pulse would not occur simultaneously, but follow one another in succession. In scientific terms, this is referred to as chirping, or linear-frequency modulation. However, this presents another challenge: Although chirping technologies are quite well developed in the infrared range, there is a lack of research on the technique's use in the terahertz range.

"We've turned to the technologies used in the microwave range," says Egor Oparin, who is a co-author of the paper.

"They actively employ metal waveguides, which tend to have high dispersion, meaning that different emission frequencies propagate at different speeds there. But in the microwave range, these waveguides are used in single mode, or, to put it differently, the field is distributed in one configuration, a specific, narrow frequency band, and as a rule, in one wavelength. We took a similar waveguide of a size suitable for the terahertz range and passed a broadband signal through it so that it would propagate in different configurations. Because of this, the pulse became longer in duration, changing from two to about seven picoseconds, which is three and a half times more. This became our solution."

By using a waveguide, researchers have been able to increase the length of the pulses to a duration that is necessary from a theoretical standpoint. This made it possible to achieve interference between two chirped pulses that together create a pulse train. "What's great about this pulse train is that it exhibits a dependence between a pulse's structure in time and the spectrum," says Oparin. "So we have temporal form, or simply put, field oscillations in time, and spectral form, which represents those oscillations in the frequency domain. Let's say we've got three peaks, three substructures in the temporal form, and three corresponding substructures in the spectral form. By using a special filter to remove parts of the spectral form, we can 'blink' in the temporal form and the other way around. This could be the basis for data encoding in the terahertz band."

Rohde & Schwarz together with Fraunhofer Institutes HHI and IAF join forces in researching 6G at THz frequencies

© Rohde & Schwarz

https://www.iaf.fraunhofer.de/en/media-library/newsarchive/cooperation-of-fraunhofer-and-rohde---schwarz-for-6g.html

While the new 5G technology is at the first stages of rollout, Rohde & Schwarz, the Fraunhofer HHI and the Fraunhofer IAF are taking a step further with demonstrations in the terahertz (THz) frequency band, related to the 6th generation wireless mobile communication (6G). The collaboration has resulted in a wireless transmit and receive system operating between 270 and 320 GHz, with further frequency extensions for potential 6G bands already in preparation.

6G research is already underway in industry and academia. While 5G introduces mmWave frequencies with wider bandwidths for higher data rates and enables new applications such as in wireless factory automation (Industrial IoT) and for autonomous vehicles, the aim of 6G is to push the boundaries of transmission bandwidths even higher.

Hello, 6G Testbed: Sub-THz Tinkerers, Welcome

  - ED TARGETT



https://www.cbronline.com/news/6g-sub-thz-ni

“Researchers need access to sub-THz testbeds to prototype multiple wireless use cases”

The world of 5G is barely beginning to be explored by businesses – its advocates tout a vision of smart factories; mobile game streaming; AR-augmented surgery; autonomous vehicles, and Pokemon Go on steroids – with network carriers rolling it out in phases this year and into 2020 in the UK, but experimental 6G work is already starting.

Texas-headquartered National Instruments (NI) gives a flavour of what that might look like this week, with the release of a sub-THz software defined radio (SDR) for 6G research, built on its mmWave Transceiver System and Virginia Diodes’ radio heads.

(The development cycle of a typical wireless standard is approximately 10 years, it notes; with 5G roll out gaining pace this year, 6G could emerge by 2029…)

Sub-THz, You Say?

With even 5G still rather more contested a term than it should be, what 6G might constitute is, at this stage, something of an open question.

Bets are being placed, however, on the use of the Terahertz (THz) frequency range (0.1 THz — 3 THz); the last span within the electromagnetic wave spectrum. (THz typically refers to 0.1–10 THz; sub-THz region is 0.1–0.3).

NI’s new gizmo, which is built on FPGAs (customisable and programmable chips) can be upgraded and customised to create a “real-time testbed for 6G research”, the company says, and is equipped with special radio heads that that can transmit/receive a wide variety of frequency bands in the sub-THz range.

Read this: Industry-First Xilinx Accelerator Card Runs in “Any Server, Any Cloud” – Fits Standard PCIe Slots

“Researchers need access to sub THz testbeds to prototype multiple wireless use cases. These testbeds must be highly flexible but also offer cutting edge performance in order to explore the boundaries of wireless performance at these very high frequencies,” said James Kimery, director of wireless research, NI.

He said the offering will “spur innovation on the way toward 6G.”

All signal processing, including coding, occurs in real-time on FPGAs added to the base transceiver system, the company said in a release today, with total system throughput is dependent on the frame structure and the number of channels used.

A typical expected throughput is 7.2 Gbps/channel, with a software front panel offering real-time visualisation of system level performance.

Can sub-THz/6G Networks… Work?

With massive MIMO-based 5G already a challenge for engineers (signals are easily block by physical structures, etc.) sub-THz/6G networks look set to require some ingenious materials developments.

As academics from Saudi Arabia’s King Saud University and France’s IETR University of Rennes put it in a joint paper, “Sub-THz Antenna for High-Speed Wireless Communication Systems” published March 2019: “Very high path loss is imposed as one of the main challenges at THz band frequencies, which poses a major constraint on communication distances.

“Additional challenges range from the implementation of compact high-power THz band transceivers, the development of efficient ultra-broadband antennas at THz Band frequencies, and characterization of the frequency-selective path loss of the THz band channel to the development of novel modulations, transmission schemes, and communication protocols tailored to the peculiarities of this paradigm.”

Other specialists at the coalface of network R&D agree.

“Admirable output powers, but only at cryogenic temperatures”

In a June 2019 paper “A Perspective on Terahertz Next-Generation Wireless Communications“, Oklahoma State University academics John F. O’Hara, Sabit Ekin, Wooyeol Choi and Ickhyun Song noted that the generation, reception, and conversion of terahertz waves in mobile devices requires “cutting-edge electronic, photonic, or hybrid approaches that push the limits of material properties and device capabilities.”

Modern photonic-based THz sources include quantum cascade lasers (QCLs); nonlinear optical-mixing sources, and ultrafast laser-driven pulsed sources and detectors.

They note: “The form factors and operational principles of these vary so widely that one-to-one comparisons in performance are very challenging. For example, terahertz QCLs can achieve admirable output powers, but only at cryogenic temperatures, whereas mid-infrared QCLs, used in conjunction with nonlinear crystals can make microwatts of tunable continuous wave (CW) terahertz (1-5 THz) at room temperature…

“All of these sources offer impressive performance in their own ways, but none so far
are easily integrated into larger digital electronic systems, which is arguably their biggest downfall for communication systems.”

Keysight extends beyond 5G with participation in 6G flagship program

The next generation of wireless communications is expected to leverage spectrum above millimeter waves.

https://www.fiercewireless.com/wireless/keysight-extends-beyond-5g-participation-6g-flagship-program

by Monica Alleven

While the wireless industry is firmly entrenched in deploying 5G networks—and in many cases, busy debunking myths surrounding it—plenty of academics and others are exploring what’s going to happen after 5G.

Test and measurement company Keysight Technologies, which has been there throughout the 5G standards process and even before that, recently announced that it has joined the multi-party 6G Flagship Program supported by the Academy of Finland and led by the University of Oulu, Finland.

Keysight actually has had a long relationship with Oulu University and has an R&D team based in Oulu, according to Roger Nichols, 5G program manager at Keysight, so it’s not as if this is coming out of the blue. According to a press release, however, Keysight is the only test and measurement provider thus far invited to take part in the program.

Keysight said its early research capability, complemented by a range of software and hardware for design, simulation and validation, will help the program accomplish its overarching goals. Those goals include supporting the industry in finalizing the adoption of 5G across verticals, developing fundamental technologies needed to enable 6G such as artificial intelligence (AI) and intelligent UX, and speeding digitalization of society.

The next generation of wireless communications is expected to leverage spectrum above millimeter waves. The terahertz waves, from 300 GHz to 3 THz, form an important component in delivering data rates of up to one terabit per second and ultra-low latencies, but they are still very much in the experimental territory.

“A lot of what’s happening up there now is still in the research phase because as you can imagine in those higher frequencies, it’s challenging to get things to work the way you want them,” Nichols told FierceWirelessTech. “We’ve been involved in that territory for quite a while,” having sub-100 GHz capability in its equipment for decades and using third-parties to extend that up into the terahertz range.

It’s not just about higher frequencies but what can be done with the wide bandwidths. For the sake of 6G, “really this is about: can we get an even wider bandwidth to deal with new applications that we haven’t thought about that have a demand for data rates that are well beyond anything we’re considering for 5G?” he said. “Obviously, going to terahertz super wide bandwidth is only part of 6G, just like millimeter wave is only part of 5G.”

Nichols points to an ITU Network 2030 white paper that describes the Network 2030 initiative and provides a comprehensive analysis of the applications, network, and infrastructure envisioned for the next big wireless transformation. That paper points to holographic type communications, multi-sense networks, time-engineered applications and critical infrastructure as emerging applications or use cases.

But nobody is suggesting it's a good idea to get ahead of themselves. Part of Keysight’s success in 5G was getting involved early and knowing where that technology was headed and the tools that are needed, plus developing relationships with academia and industry. “Clearly, we’re going to spend our time ensuring that we stay on top of that business opportunity, which is far from being over,” he said.