Partners take wraps off 5G channel sounding solution

The test solution supports the research activities aimed at exploiting the microwave and millimeter-wave spectrum within 5G networks.

For decades, propagation conditions in cellular networks have been well understood in the frequency bands from 450 MHz to 3 GHz. Starting with the commercialization of GSM systems, channel models were developed based on this knowledge.

These are widely used to verify base station and end user device performance in the lab by simulating real-world conditions. In contrast to these legacy frequency bands, knowledge of the radio channel at frequencies above 6 GHz is still limited.

Although a significant amount of channel sounding campaigns have been conducted and many results published, new spectrum in the discussed range from 6 GHz to 100 GHz requires much more measurement data.

Multiple research projects as well as the upcoming 3GPP standardization need comprehensive measurement data in order to derive suitable channel models for efficient testing in future.

The solution demonstrated comprises the SMW200A vector signal generator and the AFQ100B I/Q baseband generator on the transmitter end and the R&S FSW signal analyser on the receiver end. The transmitter and receiver are synchronised and triggered by high-precision clocking units from Fraunhofer HHI, which also serve as absolute time bases with an accuracy of 2 ns. The R&S SMW200 and R&S AFQ100B provide a wideband sounding signal with up to 500 MHz signal bandwidth and up to 40 GHz carrier frequency.

The sounding signal is based on an optimised correlation sequence. The signal analyser receives this signal up to a carrier frequency of 67 GHz, and demodulates and samples it using its built-in 500 MHz demodulator.

Application software from Fraunhofer HHI postprocesses the demodulated signal and estimates channel impulse responses in the time and delay domains. The same measurement concept could be extended for measurements above 40/67 GHz by adding external up/downconverters on both ends. A 2 GHz demodulation bandwidth could also be realised using a wideband I/Q baseband generator from Fraunhofer HHI on the transmitter end and by adding the R&S RTO oscilloscope as well as the newly released FSW-B2000 frequency range extension option for the R&S FSW on the receiver end. This flexible solution would provide an excellent dynamic range with a multipath resolution down to 0.5 ns.

Thomas Haustein, Head of the Wireless Communications and Networks Department, states: "Fraunhofer HHI’s expertise in millimeter-wave channel sounding contributes to a better understanding of radio propagation, making it possible to derive realistic channel models for the relevant wireless use cases. It will therefore provide the basis for standardising link and system design within the global 5G effort."

Alexander Pabst, Vice President Systems and Projects of the Rohde & Schwarz T&M Division, emphasizes: "Microwave frequencies will mean a disruptive change for mobile communications. We at Rohde & Schwarz are committed to actively supporting the ongoing R&D activities by providing our RF expertise. The cooperation with Fraunhofer HHI will help bring this new technology from the development labs to the real world."

Rohde & Schwarz and Fraunhofer HHI will demonstrate their solution at the NGMN Industry Conference & Exhibition (March 24-25) in Frankfurt/Main.