Measuring Massive MIMO using Over-the-Air Techniques

The path to 5G is bringing many changes to the telecommunications networks we are accustomed to today. With increasing numbers of antenna elements, higher frequency bands and new standards to regulate the industry, the approach to testing the connectivity and functionality of the future 5G network is as revolutionary as the network itself.

 

Although radio interfaces in 5G will be required to support a wide variety of services, one key aspect will be the introduction of MM with large element counts, termed a MM array. A MM array is made up of a uniform rectangular set of elements, where each element can either be single polarized or dual polarized.

 

In the majority of scenarios, the number of BS elements are targeted to have up to 256 transmit (Tx) and receive (Rx) antennas with a mix of frequency bands above and below 6GHz. Given these typical deployment scenarios, MM arrays with very large element counts will likely exist in the millimeter wave frequency bands.

 

Testing MM arrays requires a huge number of radio links for channel emulation. A typical MM antenna array of 64 elements supporting four antennas (configured as one device with four antennas, two devices with two antennas each, or four devices with one antenna each) requires 512 radio links. As 5G drives antenna counts as high as 256 elements in a single array and increased multiple antennas on devices, replacing those antennas with conducted cabled connections results in a very complex and cumbersome test setup that has difficulty scaling due to the need for a significant number of independent channels and cables. Additionally, in order to adequately test MM arrays and be able to verify all aspects of performance, the most important elements of MM, the antennas, need to be included in the testing; if cables are used, the antennas are excluded. Therefore, a different approach is needed.

 

This eBook gives a quick overview of what’s coming in 5G networks and details an innovative approach to testing the Massive MIMO antenna arrays that will be an integral part of the new technology.