One of the most critical differences between 5G/NR and legacy LTE in terms of RF environment can be summarized as follows :

• Carrier Frequency is extremely high (most commonly just slighly lower than 30 Ghz)
• Massive MIMO would be a common operation mode, meaning a lot of antenna will be used.
• Beamforming factors should be considered

Considering all of these factors, we may reach an important conclusion : Conductive testing (Direct connection between UE and Test Equipment with RF Cable) would not be acceptable in most of the testing. It means we need to do most of the tesing in OTA (Over The Air) connection.

Then a couple of questions as follows would pop up right away in your mind :

• Are we going to use the same OTA configuration (methodology) ? or to use a couple of different configuration depending on test item ?
• What kind of OTA configuration candidate we can think of ?

The firm/official answer to these question is supposed to come out by 3GPP, but I would introduce a well-described idea proposed by Intel in R4-165050(Ref [1]) as follows.

Reference :

[1] 3GPP RAN4 #80   R4-165050 : Testability considerations for NR