Collaboration delivers rapid mmWave channel characterisation

Channel measurements capture how wireless signals are affected in a given environment. For instance, channel measurements can show how signals reflect off of, or are blocked by, objects, such as trees, buildings, cars and even people. 

Wireless channel characterisation is very important for wireless researchers defining 5G technologies as it will help lay the foundation for the architecture and design of these new wireless networks. AT&T and NI believe this work will likely play a role in AT&T’s future 5G deployment, through the creation of accurate models that help map out the details of where AT&T places its network equipment to provide customers with the best possible mobile experience.

“Utilizing mmWave spectrum for mobile 5G presents many challenges which we believe can be solved,” said Marachel Knight, senior vice president of wireless network architecture and design, AT&T. “We identified early on that designing and real-time monitoring of mmWave spectrum needs to be much more precise than today’s cellular systems. With the help of NI’s flexible hardware and software platform, AT&T developed a new type of channel sounder and we’re using it to develop highly-advanced models that will work for our network.” 

Nicknamed internally within AT&T as the “Porcupine,” the channel sounder is the first of its kind and is proprietary to AT&T.

It provides real-time channel parameter measurement and monitoring capability.

The channel sounder, designed by AT&T, utilises an architecture based on NI’s mmWave Transceiver System.

This one-of-a-kind design provides several key advantages. It allows angle-of-arrival (AoA) measurements that would typically take 15 minutes or more to be completed (using pan-tilt units) to be performed within 150 milliseconds and display the results in real-time.  

The channel sounder uniquely captures channel measurements where all the data is acquired and processed in real-time.

Other channel sounding approaches capture raw data and post process to characterize the channel while only giving one-measurement every 15 minutes. The “Porcupine” on the other hand can provide about 6,000 measurements in that time.

It’s like capturing 15-minutes of action with a video instead of a still photo. A video tells the whole story, while a photo just shows a moment. 

The capability of real-time measurement eliminates the need to repeat experiments or to adjust the equipment to take multiple measurements from one location.  

Since parameter extraction is done in real-time, the integrity of collected data can also be evaluated in real-time.

Thus inaccurate data can be replaced immediately with a new set of measurements at the time of evaluation.

Using other approaches, an entire evaluation day could potentially be lost if the collected data is post-processed. 

To AT&T and NI’s knowledge, the speed and accuracy of this mmWave channel sounder makes it uniquely capable of making fast measurements of a channel.

Thus, for example, the “Porcupine” allows the measurement of 5G mmWave frequencies via drive testing.

This capability has previously remained out of reach for other mmWave channel sounders.

As the 5G ecosystem looks at new use cases for 5G such as assisted driving, connected car, self-driving cars and more, the ability to study and model vehicular channels will become ever more critical.

“The NI mmWave Transceiver System and LabVIEW system design software enabled AT&T and NI to define and develop a channel measurement system unmatched in the industry today,” said James Kimery, director of RF research and SDR marketing at NI. “The combination of PXIe and LabVIEW FPGA provided the bandwidth, data and signal processing capability, and flexibility necessary to meet the requirements of mmWave and expedite 5G deployment.”