Over the last few years, the propagation conditions in cellular networks from 450 MHz to 3 GHz have been well understood. 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.
Rohde & Schwarz will present a novel 5G channel sounding solution in cooperation with Fraunhofer Heinrich Hertz Institute (HHI) at the NGMN Industry Conference in Frankfurt/Main. The solution demonstrated comprises the R&S SMW200A vector signal generator and the R&S AFQ100B I/Q baseband generator on the transmitter end and the R&S FSW signal analyzer on the receiver end. The transmitter and receiver are synchronized 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 optimized correlation sequence. The R&S FSW 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 realized 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 R&S 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.
Better understanding of radio propagation at millimetre-wave frequencies will make it possible to derive realistic channel models for the relevant wireless use cases. It will therefore provide the basis for standardizing link and system design within the global 5G effort.
Rohde & Schwarz and Fraunhofer HHI will demonstrate their solution at the NGMN Industry Conference & Exhibition, which takes place March 24 to 25, 2015, in Frankfurt/Main.
