AUTOMOTIVE DESIGN
chosen for various items of bodywork, as well as the effects of windows and any other components such as seats or crash structures that could block or attenuate the signals. WMG (Warwick Manufacturing
Group) is a department at the University of Warwick with a long history of automotive research and development. Experts in WMG’s Communications and Connectivity group are doing research in the field of 5G applications for connect vehicles. Their mission is to acquire the knowledge needed for the UK’s automotive industry to ensure vehicles and networks can coexist and cooperate in the 5G world, enabling subscribers to benefit from reliable 5G services. The group has numerous ongoing research programmes and, in 2019, installed Europe’s first over-the- air 5G test equipment at its Midlands Future Mobility (MFM) testbed for use in connected autonomous vehicles. The group has now established
a facility for channel sounding to analyse the behaviour of 5G signals in and around vehicles. The equipment allows them to set-up transceiver pairs, including a vehicle-mounted set to emulate the equipment that’s expected to be fitted to coming generations of connected cars, to measure the signal strength at various locations.
CHANNEL SOUNDING The channel sounding equipment operates in 5G New Radio (NR) frequency range 1 (FR1) up to 6GHz and FR2, which includes all frequencies above 6GHz. To generate and analyse these signals, the team is using test and measurement equipment from Rohde & Schwarz UK. The set-up includes the SMW200A Vector Signal Generator, FSW85 Signal and Spectrum Analyzer, and RTO2044 Digital Oscilloscope, acquired through Rohde & Schwarz’s university support programme. The SMW200A lets the team transmit frequency band limited signals with carrier frequency up to 40GHz and arbitrary modulated waveforms with clock frequencies up to 2.4GHz. The FSW85 and RTO2044 enable the processing of the received signals with a maximum sampling rate of 2.4GHz.
Channel sounding experiments analyse effects such as excess path loss and delay spread
“Automotive applications will
operate in various bands in FR1 and FR2, up to very high, millimetre-wave, frequencies. We needed the multi- GHz capabilities provided by the Rohde & Schwarz equipment to get a proper understanding of the radio environment in and around the vehicle across the full radio spectrum,” says Dr Matthew Higgins, reader of 5G Communications and Leader of the research group at WMG. “As well as having a wide frequency range, the instruments deliver outstanding low- noise performance and are extremely accurate and repeatable. That helps us set up experiments quickly and allows us to rely on our measurements as a true reference for subsequent analysis.” Higgins also cites ease of use as
an important benefit of the Rohde & Schwarz equipment. “The clarity of the user interface accelerates setting up the equipment and helps us interpret the results confidently. The signal generator, analyser, and oscilloscope all present a consistent user experience.” Using this equipment, the channel
sounding experiments help analyse effects such as excess path loss and delay spread that influence quality
of service parameters like error vector magnitude (EVM) and data throughput that ultimately determine the end-user experience. Ultimately, the results will be used to inform the design of 5G-ready vehicles. “We have already gained many
insights that can help optimise the positioning of 5G antennas in connected cars. We know, for example, that a heated windscreen strongly attenuates signals at 5G frequencies, so the area should be avoided,” says Higgins. “Also, from a styling point of view, any antennas need to be unobtrusive, although ensuring best performance is obviously critical. To this end, we have analysed radio- transparent materials that can hide the antennas from view while permitting a reliable, high-speed connection. “Tomorrow’s connected cars must
live up to huge expectations and the knowledge we are acquiring now should give the industry the best possible chance of meeting them.” ●
For more information visit
www.warwick.ac.uk/wmg and
www.rohde-schwarz.com
www.engineerlive.com 11
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