FEATURE TEST & COMPLIANCE STANDARD OPERATION WLAN 802.11ay and what it means for signal transmissions

The new WLAN standard promises significantly higher data rates and larger range. The R&S FSW85 signal and spectrum analyser provides the appropriate T&M functionality, as Dr. Wolfgang Wendler, product manager of the analyser at Rohde & Schwarz, explains


he IEEE 802.11ad WLAN standard, introduced for high data rate

transmissions in the 60GHz band, can no longer provide the required data rates and range. That is why the IEEE 802.11ay extension is currently being specified, with the development of chipsets and components underway. In place of the 2.16GHz bandwidth offered by 802.11ad, the enhanced 802.11ay standard can deliver 8.64GHz total bandwidth by combining up to four channels. The available frequency range has been extended to 71GHz MIMO, with up to eight streams per channel. With only four streams at 44Gbit/s, data rates of up to 176Gbit/s can be achieved. This is additionally supported by higher- order modulation schemes such as 64QAM, and with the promise of a larger transmission range. The new standard is mainly intended

to replace Ethernet and other wired transmission standards, e.g. to transport video content to monitors, to integrate augmented reality (AR) and virtual reality (VR) and to exchange large data volumes between computers and mobile devices. Ultimately, the high bandwidth eliminates the need for complex cable installations, saving costs and allowing for a more flexible working environment. The standard also facilitates the quick connection of service providers. For example, with 802.11ay, network operators can connect base stations to the core network easily compared to using radio relay setups. In view of the wealth of new possibilities offered, many


manufacturers of WLAN applications have already started development of 802.11ay transmitters and receivers. While the technology is very promising in terms of data rates, device development is costly and complicated. Chip and component manufacturers not only need effective production technologies, but the T&M equipment must handle frequency ranges of up to 71GHz, as well as modulation bandwidths of at least 2GHz. The R&S FSW85 signal and spectrum analyser covers the relevant frequency band without any frequency converters, and also offers the necessary demodulation bandwidth. With the R&S FSW-B2001 option, it provides 2GHz internal bandwidth, turning it into a one-box solution that can measure the modulation characteristics of one channel of an 802.11ay signal, as a case in point. The instrument does this with a sensitivity of –37dB, corresponding to an error vector magnitude of approximately 1.5 per cent. A dedicated internal measurement application (R&S FSW-K97) provides all results of interest at the push of a button. Along with the tabular listing of the modulation characteristics, display of the preamble content, and the transmitted bits, it visualises diverse diagrams that enable the user to identify problems and improve transmission quality. If signals are very weak or need to be measured over the air, which is

“The new

standard is mainly intended to replace Ethernet and other wired transmission standards...”

often the case in this frequency band because the antennas are usually integrated on the PCBs, a preamplifier such as the R&S HA-Z24 can be connected to improve the signal-to-noise ratio. If more than the 2GHz bandwidth is required, this requirement can be met by combining the R&S FSW85 with an R&S RTO2064 oscilloscope to provide the necessary bandwidth. The frequency response of the combined signal analyser and oscilloscope is fully equalised; the data is automatically loaded into the R&S FSW85, with the user simply adjusting the bandwidth. Spectral measurements can be directly performed on the R&S FSW85, including preselection up to 85GHz. This feature offers substantial benefits, i.e. fewer spurious signals and higher sensitivity for spectral measurements. For OTA measurements,

strong interfering signals outside the wanted band can be suppressed to avoid distortion of results.

Of course, it is also possible to use a signal and spectrum analyser together with an external harmonic mixer, to achieve up to 5GHz analysis bandwidth for measuring modulation characteristics. However, these combinations do not offer the advantage of preselection for spectral measurements.

Rohde & Schwarz / ELECTRONICS

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