6G Sub-THz measurements and sub-THz test setup by Keysight
This page covers 6G Sub-THz measurements and sub-THz test setup by Keysight Technologies.
Introduction:
The term "terahertz or THz" refers to frequencies in 1012 Hz range.
The frequencies from 300 GHz to 3 THz (i.e. 3000 GHz) are used as THz spectrum range.
The frequencies between 100 GHz and 300 GHz is referred as sub-THz.
Terahertz frequencies use higher bandwidth and are shorter in wavelengths.
These frequencies have high propagation loss and atmospheric loss
compare to mmwave frequencies. 6G measurements at sub-THz requires very sophisticated and
high performance test equipments. These equipments are manufactured by various test and measurement companies.
The most popular manufacturers of 6G wireless test equipments are Keysight, R&S, Anritsu, NI etc.
6G follows 4G LTE and 5G wireless technologies.
6G Sub-THz Measurements
The 6G wireless technology targets to achieve individual data rates of about 100 Gbps and perhaps upto 1 Tbps. The 6G wireless devices are 100 times faster compare to 5G technology. The 6G testbed is mainly developed to test sub-THz devices in D band and G band. D-band covers frequencies from 110 to 170 GHz and G-band covers from 140 to 220 GHz.
Following Sub-THz measurements are useful during 6G device testing.
• Constellation Diagram
• Eye Diagram
• Power Spectrum with OBW (Occupied Bandwidth)
• Decoding of the 6G packet or frame
Refer Baseband Measurements,
Constellation diagram versus eye diagram and
Error Vector Magnitude for more information.
Sub-THz Test setup for 6G device testing by Keysight
The figure-1 depicts common measurement setup used for 6G device testing.
Following Keysight equipments and RF components are used in 6G Sub-THz test setup.
• AWG (Arbitrary Waveform Generator) Model M8195A used to generate wideband IF centered at 6 GHz frequency
• VDI RF Up Converter at G band frequency ranging from 140 to 220 GHz
• PSG Vector Signal Generator Model E8267D, used to generate LO frequency at 23 GHz
• RF filter (BPF) and VDI amplifier
• Rectangular horn antennas for OTA (Over The Air) Testing
• VDI RF Down Converter
• Digitizer Model M8131A
• Keysight 89600 VSA Software
Figure-1 : Test Setup for 6G measurements at sub-THz frequencies
As shown in the figure, AWG is used to generate wideband IF around center frequency of 6 GHz with 10 GHz bandwidth. The PSG is used to generate 23 GHz frequency which is multiplied by factor of 6 to obtain frequency of 138 GHz. This 138 GHz is used as LO inside VDI up converter. This modulated IF at 6 GHz is mixed with LO of 138 GHz using VDI up converter. Up converter produces 144 GHz frequency which is filtered/amplified and fed to horn antenna. The other horn antenna is used at the receiver with spacing of about 35 cm for OTA (Over The Air) testing. The received RF signal is downconverted and digitized. The digitized signal is demodulated and analyzed using Keysight VSA (Vector Signal Analyzer) Software application running in the computer system.
We can observe constellation diagram and power spectrum. One can experient with blocking the transmitted signal and observe the change in constellation diagram as well as received power level in the power spectrum. The above setup demonstrates SISO (Single Input Single Output) case using one antenna for transmit and one antenna for receive. Both M8195A (AWG) and M8131A (Digitizer) support multiple channels which can be used for MIMO testing.
Figure-2 : Testing receiver part of DUT using VSG
Figure-3 : Testing transmitter part of DUT using VSA
The figure-2 and figure-3 depicts VSG and VSA used for RF and baseband testing of DUT (Device Under Test). The setup include VSG (Vector Signal Genarator) used for 6G DUT receiver testing and VSA (Vector Signal Analyzer) used for 6G DUT transmitter testing. As shown in the setup, both keysight VSG and VSA are used for preparation of 6G testbed without any DUT in between. Once this calibration is made either VSG or VSA is used for DUT testing to test its receiver or transmitter functionalities respectively. Refer article on basics of Vector Signal Generation and Analysis >>.
About Keysight Technologies
The US based company with headquarter in california manufactures electronic test and measurement
equipments and T&M software. The keysight offers test and validate products for 4G LTE, 5G, 6G,
IoT (Internet of Things), 800G, quantum solutions, car manufacturers and so on.
Visit Keysight.com for more information.
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