While some companies may be claiming victory in the first heat of the 5G race, it’s clear the real winners will most surely come from the middle of the pack. Taking advantage of drafting in the path of telecom giants, these nimbler competitors are making informed decisions and streamlining their approaches.
To make such headway, a number of companies are adopting the approach of rapid prototyping, testing, and deployment of network architectures enabled by nimble, self-programmable RF test devices. With a few of these devices, a laptop, a simple GUI, and a USB cord, designers are quickly confirming or denying various networking and signal management techniques and identifying the best components for their unique signal chains. They’re also discovering how to create lower-cost, lighter-weight ATE solutions that can be duplicated, trained, and deployed in various regions.
MIMO Benefiting from Programmable Testing Devices
The small-cell, millimeter-wave, and massive multi-input multi-output (MIMO) system, currently considered one of the best 5G wireless network approaches, is also one of the most complex. While there’s tremendous advantages and efficiencies of a multi-path network, the creation of a test system to perform common simulations, such as fading, becomes exponentially more challenging. This is when many MIMO system designers are enjoying the ability to try subtle tweaks, out-of-the-box ideas, and major rethinks all in one day with the help of their versatile and easily programmed RF test devices.
How Did It All Develop?
So how did self-programmable test devices come to be in wireless telecom? You might say they fell off a bench. The shared test bench of a RF/microwave component and/or subsystem engineering department is typically home to at least one pre-programmed high-frequency benchtop instrument. They’re operated by a small screen and front-panel keyboard along with a library of dozens of necessary codes. They’re also costly.
Resourceful engineers and test techs at these companies who’d grown tired of getting squeezed for time on the few (if any) full-featured instruments, also recognized the amount of overkill these instruments were when it came to their own unique test or simulation within certain frequency bands. As the burgeoning programmable RF/microwave test device market was taking shape, early evaluations revealed that the approach was not only efficient in the lab, it was even more valuable to a company’s techs in the field who were carting around and protecting full-featured pieces of equipment. Once in this team’s hands, the programmable trend gained steam.
Easy Connectivity and Programmability is Key
Among the most commonly adopted programmable devices are those featuring driver-less USB HID compatibility. These devices typically operate from a Windows-based GUI or by tapping into a library of Windows and Linux APIs provided by the manufacturer that support Python, C#, C++, MATLAB, Java, and LabVIEW.
The reason USB HID compatibility appears to be a leading a choice is that it avoids the difficulties inherent in using older serial or IEEE-488 interfaces when implementing over standard USB. As a result, RF/microwave and wireless test system designers don’t need to install kernel-level drivers. This makes setup fast, and possible even with low-cost embedded computers like a Raspberry Pi.
Mobile Wi-Fi for Trains
One application area for attenuators is an ultra-efficient Wi-Fi system for commercial and commuter rail companies. Andrea Oriolo, a Co-founder and VP of Operations of Italian Mobile Wi-Fi specialists at Fluidmesh, used Vaunix’s Lab Brick attenuators (see figure) in its rail applications. He notes, “The Lab Brick attenuator was really easy to set up. It was truly as simple as plugging in a USB cord and allowing the automated software to load.”
Fluidmesh created a radio that used a set of predictive algorithms to keep and hold the best signal strength and bandwidth while simultaneously moving to a second radio before leaving the first in a make-before-break handover. The challenge was then being able to create a simulation of the multitude of nuances that would happen in real time when the radios were deployed on trains.
The company had to contend with a dynamic environment with many transitions—left turns, right turns, moving nearby and far from an antenna—to effectively simulate the roaming of the onboard radio. Meanwhile, simulation also had to consider all of this happening in a crowded environment full of obstacles, such as tall buildings or mountains, that can absorb and reflect signals. Not to mention other moving vehicles and electronic devices that could interfere with signals.
In the past, Fluidmesh's only effective way to simulate this was by manually adjusting the signal strength of the radios while riding the trains themselves and recording the data in real time. This was an arduous and time-consuming exercise that sent its team to the internet to find a better way. They quickly discovered how a portable and easily programmable RF attenuator would allow them to quickly and perfectly attenuate their RF signals and simulate the exact RF signal fading they had observed when the trains moved between various antennas, and among obstacles.
Fluidmesh was able to integrate the attenuators with its existing wireless network ATE system and create the simulated environments and repeatable mobilized scenarios that were needed. The team was able to test network performance theories and adjust their base-station equipment and radios with ease. This reliable simulation also became the key to developing a new signal transmit/receive algorithm that allowed their technology to mature quickly and speed their integrated, mobile Wi-Fi solution to market.
Characteristics to Look for in Self-Programmable RF Test Devices
Ready to give programmable wireless testing a try? Keep these things in mind when choosing your preferred vendor:
- Continuity: That is, whether you’re operating a signal generator, phase shifter, attenuator, or switch singly or together, all adjustments you can make should be performed almost identically. This makes everything from setup through operation far easier than if each user interface (UI) was different.
- Configurability: Each time you configure, reconfigure, and control, you should be able to do so from a single interface, rather than through layers and layers of menus.
- Automatic identification: Once you connect the device to a laptop or PC, the software should automatically identify it and load the parameters (attenuation, phase, power, and sweep configuration) stored in the device.
- Intuitive settings: Any programmable RF test device worth its merit should also allow you to change settings on the fly to see the effect on your device under test (DUT), such as an amplifier on an evaluation board, or an IC, for example.
- A full suite of bandwidth choices: Look for companies who can be a resource for test sets across your many possible frequency bands. The adoption of a programmable approach will be quick, so you won’t want to source from multiple vendors with different GUIs.
- Optional high-performance features: To keep total ATE costs the lowest, look for a manufacturer that has designed both basic devices and more advanced high-performance models, so that you can be assured that you’ll only be buying the functions and performance levels you really need.
- Robust yet portable packaging: To achieve the reliable and repeatable performance, and the long-term durability required of mobile test systems, look for your portable test devices to be packaged in proven aluminum cast housings. They should also fit in the palm of your hand.
- Custom capabilities: Soon after you’ve hit your stride in configuring and reconfiguring test sets, you’re likely to recognize a pattern of common combinations of components. Look for a manufacturer who can integrate these functions into a chassis and deliver the ideal integrated unit for your application.
Scott Blanchard is a Co-Founder and President of Vaunix.
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