Hello from the Keysight R&D center in Malaga Science Park, Spain.
In 2022, there will be 60 billion devices connected.
Low-power wireless access technologies has the potential to connect 60-percent of them.
NB-IoT is probably the best technology providing low-power low-cost connection to billions of devices.
The design and implementation of NB -IoT devices presents test challenges.
Some are similar, and many are different from those with smartphones.
But the common factor is that engineers need to be able to easily recreate scenarios in the lab
as well as being able to perform accurate and repeatable measurements.
The use of a network emulator like the Keysight UXM can greatly simplify this task
and help engineers bring reliable IoT-enabled devices to market more quickly.
Let me show you now a real demonstration of how you can test NB-IoT using the UXM.
Once NB-IoT cell mode is set, operation mode can be flexibly configured.
In this case we have an in band UE.
When in band is selected, a new group of settings appear
at the bottom of the screen to enable the configuration of the LTE host cell.
The connection mode is configured as over control plane.
This way IP packets will be transferred using a NAS container.
Now let’s configure basic parameters
like the output power, frequency band and physical resource block
within the LTE host cell where the NB-IoT cell is going to be allocated.
Let’s also enable the downlink and uplink schedulers
so that there is data being exchanged with the device under test at all time.
At this point, this is all the configuration that is needed
and we can now turn on the cell.
In the message summary tab, 2 sets of broadcast messages are shown.
One of them corresponding to the LTE host cell
and the other one belonging to the NB-IoT cell.
Let me now turn on the UE.
Now the NB-IoT UE is registering the UXM cell as shown in the status bar.
We can see more details of the protocol messages being exchanged from the message summary tab.
Let’s now take a look to the status of the transmissions from the BLER throughput tab.
In this tab detailed information of the transmissions is reported in real time,
so that you can analyze the quality of this for the selected modulation and coding scheme.
The statistics of the HARQ feedback and retransmissions is also shown here
for both downlink transmissions
and also for uplink transmissions.
You can also check the device is properly transmitting
for different configurations of the scheduler.
Let’s for example change the coding scheme
and see how the throughput is immediately implemented in the uplink
with still no BLER in any of the transmissions.
Once the receiver is tested from the MAC layer,
let’s also make sure there is IP connectivity.
For that let’s ping the UE and check that we can get the response back.
This way we are able to confirm that all the layers from NAS to physical layer
are working as expected in the UE side.
With this demonstration you can see how easy you can debug
and benchmark your NB-IOT device
using a very friendly and easy-to-use interface.
However, test complexity dramatically increases
given the large number of different settings that are needed to be tested.
And therefore automation is a key aspect.
For this case in particular we are going to use the Keysight test automation platform or TAP.
This tool offers test flow sequencing
and analysis capabilities that help reduce the time taken to develop hundreds of test cases.
Let’s see how easy it is
for example to create a test that automatically sweeps over all of the modulation
and coding schemes in the uplink.
We can start by adding the step that configures the UXM cell as NB-IoT
including basic parameters as done earlier.
Then we would add the steps to activate the cell
and AT commands to automatically switch on the device under test.
Once we have the steps added to register the UE
we are going to set up a sweep loop to check the result over multiple MCS.
I have also included a delay in the sequence
so that we can see how the throughput changes over time.
OK. So we are all set and we can now click Run.
In the bottom of the screen it is the UXM user interface
which is going to show in real-time the changes applied from the top.
Switching on the UE…
and now the UE is registered.
In the throughput tab the green line is showing the uplink throughput
and you can see it change over time
given we are automatically changing the modulation and coding scheme.
After covering all the MCS, the test is finished
and we can now inspect the results.
And we have also integrated this technology
in our conformance and design & verification test system.
This way, we are providing the most complete solution in the market
And we did this in a record time thanks to our test system architecture.
We are now ready to test 3GPP NB-IOT test specifications.
Let me show you how we do it
The NB-IOT conformance test cases are executed in our test manager tool.
This is the same environment that we use for running LTE RF and RRM test cases.
For example, let´s run the reference sensitivity level test case.
We have the possibility to select the band, the frequency and the environmental conditions.
Next, we can see some basic test case parameters.
After test campaign is configured, the test case execution can be started.
NB-IOT conformance test case will control
and monitor UXM application via remote interface.
All the test steps are performed automatically.
In this case we are checking if the MAC throughput is above 95%
when DL sensitivity output power is configured.
Coming back to the test manager,
the user can check the verdict in the test result browser.
The trace studio is a useful application
that shows the cell basic configuration,
reference to the sample, test case version, environmental conditions and result.
Finally, the Trace Spy, is a great tool to review the test case logs.
The user can check the content of the configuration primitives as cell configuration
and RRC and NAS messages exchanged with the NB-IOT device.