Using traditional analog beamforming, you can create a single beam by applying a phase delay (time delay) to each antenna element. However, when you need multiple simultaneous beams, you can apply a phase delay to each incoming signal and then add the beams. The most flexible approach is full digital beamforming for which each antenna has its own digital transceiver. With full digital beamforming, you can use a flexible number of beams and beamforming approaches and change them at will.
However, in general, full digital beamforming is limited to lower-cost transceiver technologies, likely below 6 GHz. Digital beamforming testbeds require a dedicated analog baseband channel for each antenna. The financial and power consumption costs make a fully digital beamforming mmWave system suboptimal. But with hybrid beamforming, you can still take advantage of beamforming technology while keeping the overall system cost lower. That’s why it is predicted to be the primary approach used for mmWave technologies.
With the NI mmWave Hybrid Beamforming Testbed, you can conduct hybrid beamforming by moving signals from the analog to digital domain. This mostly digital transceiver system combines an off-the-shelf phased array for the analog domain with the mmWave Transceiver System, additional FPGAs, and timing and synchronization modules to incorporate the digital domain. You can use this system to test a base station with up to eight antennas communicating with a maximum of eight user equipment (UE) antennas.
Figure 2. High-Level Testbed Architecture
mmWave Transceiver System
The mmWave Transceiver System is a software defined radio solution that you can use for system prototyping. It comprises a PXI Express chassis, controllers, a clock distribution module, FlexRIO FPGA modules, high-performance FPGA modules, high-speed digital-to-analog converters (DACs), high-speed analog-to-digital converters (ADCs), LO and IF modules, and mmWave radio heads (see Figure 3). You can modify this off-the-shelf, modular prototyping system to accommodate a wide variety of channels and configurations. Figure 4 shows a typical configuration.
Figure 3. mmWave Transceiver System
Figure 4. mmWave System Diagram
Learn more about this system’s hardware in the white paper, “Introduction to the NI mmWave Transceiver System Hardware.”
Off-the-Shelf Phased Array
You can combine the mmWave Transceiver System with an Anokiwave phased array to create an off-the-shelf phased array solution. For example, the phased array in Figure 5 is a 64-element planar antenna that works with Anokiwave’s AWMF-0108 ICs to allow for hybrid beamforming.
Figure 5. Anokiwave 5G Phased Array
With the modularity of this testbed, you can integrate phased arrays from other vendors.