Webinar: How to perform IoT device testing using the LTE Callbox

Public networks are not adequate for cellular IoT device testing in production line testing

As cellular networks become the standard way to connect IoT devices, a lot of manufacturers and developers are discovering that the public cellular network is not a proper test  environment.

Testing requires network-side measurements and the ability to test different operating conditions in a repeatable way.

This webinar will show how to use the YateBTS LTE LabKit as a “call box” to provide a locally-managed LTE network for IoT device testing and development, how to get performance measurements for your device, how to control network configuration, and how to simulate different coverage conditions.

IoT product development testing

The big question is how do IoT products behave under different network conditions? There are different tools that are available through the LabKit to support both application and hardware testing.

Tools for IoT product development testing process

1. Protocol tracing with Wireshark
Wireshark provides visibility on what’s really happening on the radio interface for cases such as below:

  • if you have a device that might be not connecting to the network as quickly or as reliably as you expect,
  • if you have a device who’s only IP interface is through your mobile network

With Wireshark you can look into data packets that are actually carrying a user traffic payload uplink and downlink and see the traffic at the IP level depending on what kind of encryption is in place. You get visibility into these packets and you can see exactly what the application is doing on the IP interface from the IP layer all the way down to the LTE MAC layer.

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2. Acting as a network simulator software for network configurations
In fact, the Labkit enables its own private network.
There are systems that require this testing and they go by different names, but they all do pretty much the same thing and work in pretty much the same way in LTE. Examples from our customers:

Roaming testing

A mobile operator who uses the LabKit for roaming testing to see how their devices are going to behave in networks that have inconsistent configurations

Public service messaging
Multiple customers who are checking how devices respond to public service messages like in the United States presidential alerts or in Japan the earthquake tsunami warning system.

In short, in the configuration directory of the LabKit eNodeB there is a set of XML files, and these XML files get translated in real time into what are called SIBs or System Information Blocks. This system information blocks describe to all the UEs, all the IoT devices in the service area, how the cell is configured and what services it offers and can be edited by hand.
The webinar video shows examples of GSM and LTE SIBs inducing SIB7 for GSM network, LTE SIB2, SIB6 for UMTS 3G network, SIB12.

Multiple LabKits - One core network -> IoT Mobility Testing

Multiple LabKits can be attached to any core network (Hosted Core, Minicore) and then operated in any combination of LTE or GSM. They all become part of the same network and they use the same set of SIMs.

Mobility testing in Internet of Things (IoT) is done by giving the impression that the device under test is physically moving from the coverage area of one cell on to the coverage area of another and then observing the behavior of the IoT device. The cells can be LTE cells, GSM cells or one could be LTE and one could be GSM GPRS, and IoT mobility testing stimulates what happens when a device under test moves from an LTE network into an area that doesn’t have LTE coverage and has to fall back to a 2G network.

The scenarios above and others can be achieved by attaching two LabKits for example to a core network and then altering their transmit power to simulate the movement of the device under.
Plus you can also simulate roaming if you have a Minicore so IoT mobility between across operators.

Hosted Core used to connect more LabKits to iit
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Testing IoT device emissions for electromagnetic compatibility

The LabKit can also be used for hardware testing and measuring device (radio) emissions to ensure that the device isn’t going to cause electromagnetic compatibility problems in the place where it’s going to be installed.
Electromagnetic compatibility or EMC refers to different items of equipment to be used together and is a regulated requirement going back almost as far as radio technology.
If there is a device that is going to be installed in a situation where emission control is very important, let’s say on an aircraft, then compliance testing is needed to ensure that the emissions that come through the device under test aren’t going to cause these EMC problems.
Watch the webinar video to preview a demonstration of radio emissions monitoring for an IoT device under test and the actual hardware used.

IoT Production line testing

Production line testing in IoT is really about making sure that the device has been assembled and configured correctly before shipping or in general distribution to customers, and this is the type of activity that goes on in the factory at the end of the assembly line. It can be referred to as functional testing, the term used in manufacturing.

Test control system for iot production line testing

Typical production line testing automation setup:

  • IoT platform probably cloud based
  • EPC – Evolved Packet Core
  • eNodeB/BTS test equipment, in our case the Labkit
  • Mobile IoT device

Types of production lines testing

End-to-end testing

End-to-end testing for IoT is something that happens between the mobile IoT platform and the device under test in order to simulate a real scenario and test the overall functionality and performance of the setup ensuring the everything works and behaves as expected.
For this setup you will need the Labkit that provides a full-blown LTE network, your standard production IoT platform, your standard production SIMs, including eSIMs if you will use the Minicore for testing as well.

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RF (radio frequency) testing

The reason you need RF testing and RF testing equipment is to check against marginal devices because you have devices that may pass simple end-to-end testing, but if they get out in the real world they’ll perform badly because they have maybe problems with connectors or cables or bad solder joints.

Types of RF testing: Uplink and Downlink frequencies

  • Uplink

Uplink in IoT is the communication link from a device to the network hardware, in our case the IoT device under test to the LabKit (LTE receiver), and there we’re worried about Path Loss and SNR- Signal Noise Ratio.
In IoT device testing a certain path loss decibels value is expected but if that number were significantly larger that would tell us that there’s some problem in the device under test. Again, maybe a bad solder joint, a bad connection, a bad cable or maybe an assembly problem.

  • Downlink

Downlink occurs when the communication link is from the network hardware to the device, in this case from the LabKit (LTE network) to the device under test. In downlink measurements, the device under test is reporting back to the network how it sees the signal coming, how it sees the network signal and the downlink.

Iot device testing using the RF test chamber

Which are the benefits of conducted testing?

  • No random devices that jump onto your test network
  • No random towers that the phone will try jumping over to you
  • Avoids having the LTE call box emanate signals to outside world

How to avoid transmit signal leakage back into the receiver (LTE Labkit) aka jamming yourself?

  • Use attenuation on TX power splitter as option one so basically plenty of attenuation
  • Use a high isolation splitter- at least 20 decibels of isolation
  • Use a circulator, which will also give you at least 20 decibels of isolation but is band specific and more expensive
  • Use a duplexer, which is also band specific
  • Learn more on how to connect the Labkit to the chamber in a conductive way by watching the video.
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isolated RF test chaber

Fact is that these devices without proper isolation for connection can produce enough power to damage each other. So, you can permanently damage a LabKit or other test device with the power in a direct connection to an IoT device.
Watch the video to learn more about the different types of measurements including RSRP, RSRQ, and their application.

Webinar Speakers

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David Burgess
Founder YateBTS

David has designed and written software defined radio (SDR) applications for cellular protocols for about 20 years, in GSM, UMTS, LTE, and other protocols.

Since helping found YateBTS in 2014, he has been developing the LTE and SatSite products, based on the YateENB LTE implementation.

Prior to working with YateBTS, David was the main founder of the OpenBTS project.

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Robert Ghilduta
CEO of Nuand

Nuand has been developing and maintaining the bladeRF platform, an open source Software Defined Radio, since its original Kickstarter campaign in 2013.

With the release of the latest bladeRF 2.0 micro, Nuand is focusing on the needs of MIMO OFDM waveforms such as 802.11ax and 5G LTE. With decades of combined experience in software defined radios, enterprise networking equipment, and defense, Nuand is pushing the envelope of what is possible with low-cost SDRs.  

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