Building a Remote RF Testing Position
As a result of the COVID-19 pandemic, many operators were faced with staffing challenges at physical lab locations. To maintain business continuity, the demands for continued testing forced many to implement new testing tools. One of those tools was the Remote RF Testing Position.
An RF testing position has an RF shielded box containing a Device Under Test (DUT), and various RF signals are fed into the shielded box through a set of variable attenuators. With a regular RF testing position, the tester is there to operate the attenuators and the DUT. In the case of a remote test position, the tester is not in the same physical location. Therefore, some additional capabilities are required.
Remote Device Control and Logging
First, the tester must have a way to operate, monitor and capture logs from the DUT remotely. The simplest way to do this is to use screen mirroring software to operate the device from a remote location. This works for user experience testing. The smartphone in the RF shield box is connected via USB to a local host PC which is running the screen mirroring software. The tester then uses a remote desktop application to access the host PC. However, this method cannot capture logs from the device since the USB port is used for screen mirroring control.
Sometimes it is necessary to look deeper into device behaviour, and because screen mirroring cannot enable this capability, an alternative solution must be considered. In cases like this, DUT logging software is required on both the DUT and the local host PC. This is a common testing arrangement that is used for testing in the lab and drive testing in the field. However, in the case of a remote test, the tester accesses the local host PC remotely using a remote desktop application.
Remote Attenuation Control
The second difference with a remote RF testing position is related to attenuation control. Since the tester is no longer physically near the variable attenuators, they must be software controlled and the tester must have the ability to operate them from a different physical location. Some labs will create in-house software to control the attenuators, while others will use purpose-built software tools.
Off-The-Shelf Solutions
Some operators will create these positions themselves using components from different suppliers. However, there are off-the-shelf solutions available. Acentury offers two different Remote Test solutions.
The first is the LAMTA-RTP Remote Test Position. This a self-contained single test position that includes an RF shield box, a 4-channel software-controlled attenuation array and PC-based LAMTA software. It accepts four (4) independent RF feeds and the LAMTA software controls the signal attenuation on each path. The LAMTA software can even set up, perform and repeat tests that simulate roaming and handover between the different signals. This saves the tester a lot of manual effort and ensures the test conditions are repeatable.
For larger implementations, the LAMTA-RTS Remote Test System supports up to eight (8) remote test positions. Instead of having software-controlled attenuators at each test position, it uses a central software-controlled RF switch matrix. This has several benefits.
Immediate Cost and Test Simplification Benefits
The central RF switch matrix is a lot more capable than a simple attenuator array. Not only does it control the attenuation for individual signal paths, but it can also mix the RF signals to create new combinations. In this way, it can replicate roaming and handover testing under complex RF scenarios such as MIMO and Carrier Aggregation. These are difficult or even impossible to do using simple attenuators.
The individual remote test positions are less expensive since variable attenuators are not required at each location. All signal attenuation and routing are done at the central RF switch matrix.
The installation of the remote test solution is less complex as well. With a central RF switch matrix, the amount of RF signal distribution is significantly reduced. The individual RUs are connected directly to the switch matrix inputs. An RF patch panel is no longer required. Each remote test position can be connected to the RF switch matrix with a single RF feeder cable instead of several. This also reduces cost, clutter and the need for regular re-patching.
Acentury LAMTA enables more testing at lower cost
Remote testing is becoming a regular practice for mobile network operators. Even post-COVID, it provides greater flexibility for testers and lab managers. The choice for operators is to create remote test positions themselves from individual components or implement an off-the-shelf solution like LAMTA.
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