Collaboration brings together electronic and photonic technologies

For several years, Rohde & Schwarz and the IEMN team under Prof Guillaume Ducournau have researched high-frequency measurements and the integration of Rohde & Schwarz test and measurement solutions with photonic technologies to speed up advances in emerging 6G technologies.

Studying new spectrum resources will assist in advancing future wireless communications systems. Backhaul frequencies are predicted to grow once the E-band communications market is saturated. Potential frequencies such as D-band (110-170GHz) systems are anticipated to enter the market sometime after 2025, while H-band or sub-THz bands up to 300GHz will come sometime after 2030. Developing new architectures and test systems to characterise mmW/THz performance at the component and system levels is essential for these wireless trends.

Addressing the very high end of the millimeterwave spectrum (300GHz and beyond) is demanding on the component and system levels. Instrumentation has recently encountered several advancements, including vector network analysers, signal and spectrum analyser frontends and sub-systems. The IEMN performs state-of-the-art THz component and system characterisation with the R&S ZNA vector network analyser and various frequency converters covering frequencies from the millimeterwave range up to 1.1THz like the R&S ZC1100.

Recent research collaborations in electronic and photonic technologies have proposed a super-heterodyne architecture enabling channel aggregation from the V- band (40-75GHz) or E-band (60-90GHz) to the THz spectrum. The THz carrier is obtained by frequency multiplication with a photonics-based local oscillator synchronised to a reference frequency. Rohde & Schwarz supported the testing team in Lille with a state-of-the-art R&S SMA100B solution that allows for ultra-low phase noise reference signal generation. This instrumentation approach enables a spurious-free local oscillator feed signal for the THz upconverter/downconverter, limiting spurious tones in THz spectra.

The system is the first to successfully integrate THz frequency duplexing and allow simultaneous transmission and reception at both ends with a single antenna pair. After validating the system performance in a lab, it was tested in Germany with two pairs of antennas over a distance of 150m as part of the EU-Japan ThoR project, followed by outdoor, over-the-air tests in France over a distance of 645m with a system transmission rate of 12.6Gbps. This is the maximum distance achieved by a THz duplexing system in the 300GHz band.

Prof Guillaume Ducournau, head of THz wireless communications research at IEMN, says, "With our expertise in THz technologies, such as optoelectronic THz photomixers, high-speed electronic receivers and THz instrumentation, we are committed to researching new 6G areas, developing prototypes, verifying technologies and proposing advanced measurement services for our collaborators. To cope with the challenges ahead, we are glad to continue and expand our collaboration with Rohde & Schwarz and develop a solid foundation for industrialisation."

Taro Eichler, technology manager at Rohde & Schwarz, says, "We are delighted to collaborate with IEMN on integrating electronic and photonic technologies for THz communications and hope to extend the approach to other applications. The research findings will also provide valuable input for industry specification groups, such as the recently created ETSI ISG THz, as well as other standardisation bodies."

The company actively supports 6G research activities across Europe, Asia and the US while contributing to research projects, the work of industry alliances, and collaborating with leading research institutes and universities. The company's test and measurement expertise and solutions are opening the door to the next generation of wireless communications for commercial deployment by 2030.