Why do mmWave channel measurement campaigns continue to be a focus for the entire industry?

As the 5G standardization effort moves forward, mmWave channel measurement campaigns continue to be a focus for the entire industry. The challenge with mmWave spectrum is that it is not well understood and the deployment models may in fact be very different from traditional cellular networks below 6 GHz. mmWave beams are highly directional and the mmWave channels change very rapidly, hence, it is critically important to understand channel behavior and beam fluctuations with respect to time. Traditional channel sounders take measurements serially, meaning they essentially take a “snapshot” of the channel in one direction before moving to another angle and acquiring another snapshot to arrive at a 360-degree view. The time between snapshots varies with the equipment and if the channel changes in the time it takes to switch and setup for a new snapshot, valuable data may be lost. Additionally, traditional channel sounding systems take these snapshot measurements and then post process the data by piecing together the various views. Given the number of measurements required, it may take hours or even days before a holistic picture of the environment can be generated.

To combat this challenge, NI and AT&T collaborated on one of the world’s fastest mmWave channel sounders for 5G. The state of the art system measures the channel from a 360-degree perspective in real-time. The channel sounder system utilizes a unique antenna design developed by AT&T that deploys 16 quad-horn antennas yielding 64 elements configured in a 360-degree semi-sphere where data from each mmWave radio-head is captured and processed in real-time. No more waiting in between snapshots.

Several PXIe FPGA modules process four independent signal streams in real-time using IP developed by NI in LabVIEW system design software. Instead of capturing and storing I/Q data in a singular direction and then stitching together the snapshots to construct a picture off line, the Porcupine delivers full channel impulse response in milliseconds. Most importantly, AT&T can get a picture of the mmWave channel within the coherence time – especially valuable when deploying and designing 5G networks.