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Hi, I am Mike Wohlert, business development engineer at Agilent Technologies. This is
the last in a series of three LTE-advanced carrier aggregation demonstrations using Agilent's
new UXM wireless test set. For this demo, Akhilesh Daniel, our product manager, is here
with us to show how to perform CSI measurements. He will also show you the impact of channel
quality on data throughput. As in the other videos in this series, the demo setup uses
a commercial LTE-Advanced category 4 device. Over to you, Akhilesh. Thanks, Mike, let's
get started. CSI is very important for mobile networks. A UE reporting incorrect CSI, which
is CQI, PMI, or RI will cause misuse of valuable allocation either with excessively-protected
data or higher-than-optimum retransmissions. So ensuring the UE reports CSI correcting
is vitally important. We will start with the UXM's bler vs. time measurement. The blue
trace shows the downlink IP data throughput over time, and the red trace shows the uplink.
With no channel impairments enabled, this device achieves 145 Mbps downlink and 25 Mbps
uplink. I will select the RMC configuration. You can see the allocation tables are set
to provide the reported CQI values. The allocated values can also be set by the user. Now I
will navigate to the CQI histogram's stream. You see a CQI value of 15 and an RI value
of 2. This means the UE is reporting that the channel can support two code words with
a CQI of 15 for the maximum throughput that can be delivered. Now let's see how that changes.
I will select the primary cell and introduce some fading. You can see a range of CQI values,
depending on the faded signal. The rank index shows that two code words can still be supported.
Next, I will add a bit of Gaussian noise, and you can see the results are different.
The measurement results now show that for some occurrences the UE can support two code
words with a CQI of around 10. And for other occurrences, it can support only one code
word with a CQI of 15. If we come back to the bler vs. throughput screen, we can see
the impact on throughput. The throughput is diminished, as expected. Now if we disable
the noise and fading, you can see the throughput recovers to the previous levels, which verifies
that the device is responding well to the channel state. Back to you, Mike. Thank you
Akhilesh. We just saw how easy it is to perform CSI measurements with the UXM and validate
that the device is recording correctly. Having integrated AWGN and fading greatly simplifies
the test engineer's benchtop, and the UXM's large touch interface enables you to quickly
gain new insight about your device's performance. With the UXM, you can assess your design readiness
with greater confidence. Is your design ready? For more information, visit the website on
your screen. Thank you for watching.