Massive MIMO Array Testing using a Programmable Phase Matrix and Channel Emulator

One key differentiator of 5G networks is the incorporation of massive MIMO beamforming to boost network capacity. Implementing Massive MIMO requires many antenna elements for both the base station and the device; testing these implementations would theoretically require a lot of hardware resources.

 

Performance testing proposed in this paper is based on using a combination of a phase matrix splitter/combiner function and a high-fidelity radio Channel Emulator (CE). Connecting the massive MIMO array of elements to the CE via a phase matrix allows for simplification in the amount of hardware required. The phase matrix provides a single phase-adjustable connection between each input port to each output port that can be used to model a single spatial direction, like having a test probe in a chamber. The signals on this virtual probe are then supplied to the CE. The purpose of the CE is to provide simulated mobility, signal correlation, and multipath spread, and possibly noise interference to the test system. The virtual probes define the spatial clusters observed by the massive MIMO array, while the rest of the channel is simulated in the CE and connected to the User Terminal (UT). Thus, with the combination of the phase matrix and CE, a given spatial-temporal channel model can be created in a more efficient manner than by using the resources of the radio channel emulator alone.

 

This white paper discusses massive MIMO testing using an efficient method of utilizing hardware resources, specific to one of the 3GPP categories of 5G implementations below 6GHz. The system is based on using a phase matrix to emulate the angular behavior of the propagation via virtual probes, combined with a radio channel emulator to create the temporal, multipath, and correlation behavior of the propagation. This integration creates a cost effective, yet realistic, solution for massive MIMO testing.