The Institute of Electronics, Microelectronics and Nanotechnology (IEMN, Lille, France) and Rohde & Schwarz have expanded their collaboration to research THz communications that utilise photonic technologies. In a recent breakthrough, IEMN researchers achieved a significant milestone when they generated a 300 GHz bidirectional link over an outdoor distance of 645 m for use in future 6G backhauling scenarios. Crucial to the success of the performance test setup was the R&S SMA100B microwave signal generator from Rohde & Schwarz, providing an ultra-low phase noise signal that accelerates THz communications research and development, positioning it for industrialisation.
Sub-THz communications systems up to 300 GHz are becoming a reality. Instrumentation, testbeds and metrology are urgently needed for these new frequencies, demanding approaches that fill the gap between the millimeterwave and optical bands.
Over the past years, Rohde & Schwarz, in collaboration with the IEMN team led by Prof. Guillaume Ducournau, has dedicated research efforts to high-frequency measurements and integrating Rohde & Schwarz’s test and measurement solutions with photonic technologies to accelerate the development of emerging 6G technologies.
Studying new spectrum resources will prove beneficial for the progress of future wireless communications systems. As the E-band communications market becomes saturated, backhaul frequencies are expected to increase. Market entry of potential frequencies such as D-band (110-170 GHz) is projected to occur after 2025, while H-band or sub-THz bands up to 300 GHz are anticipated to follow after 2030. Developing novel architectures and test systems to characterize mmW/THz performance at both the component and system levels is very important for these wireless trends.
Addressing the extremely high end of the millimeter-wave spectrum (300 GHz and beyond) presents considerable challenges at the component and system levels. Recent advancements in instrumentation, including vector network analysers, signal and spectrum analyser frontends, and sub-systems, have facilitated progress.
Recent collaborative research between electronic and photonic technologies has proposed a super-heterodyne architecture that enables channel aggregation from the V-band (40-75 GHz) or E-band (60-90 GHz) to the THz spectrum. The THz carrier is achieved through frequency multiplication with a photonics-based local oscillator synchronised to a reference frequency. Rohde & Schwarz supported the testing team in Lille with their advanced R&S SMA100B solution, facilitating ultra-low phase noise reference signal generation. This instrumentation approach enables a spurious-free local oscillator feed signal for the THz upconverter/downconverter, effectively 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’s performance in a laboratory setting, it underwent testing in Germany with two pairs of antennas over a distance of 150 meters as part of the EU-Japan ThoR project. Subsequently, outdoor over-the-air tests were conducted in France, covering a distance of 645 meters, with a system transmission rate of 12.6 Gbps. This achievement represents the farthest distance achieved by a THz duplexing.