The purpose of the OTA test is to verify that the equipment propagates the electromagnetic waves as expected and that it receives low power signals from the base radio station, for example, and still manages to maintain the established communication with a quality level considered adequate.
The tests are radiated tests performed inside a completely anechoic chamber, composed of an arc of 23 antennas and a turntable that allows the rotation of the equipment being tested.
For wireless devices, two types of tests can be performed: radiated power and isotropic sensitivity, generating a 3D diagram for each of these parameters.
It is possible to generate radiation diagrams for antennas (active and passive) and obtain parameters such as gain, efficiency and directivity. The generated graphics allow the analysis of the best and worst case points and also the comparison between results, for example.
The Over-The-Air Performance test is extremely important to verify the design quality of the equipment’s wireless technology transmission system. It is also crucial for adapting to the markets in which it will be sold, as it allows its behavior to be validated at different frequencies and to check whether the radiation diagram is suitable for the environment in which it will be implemented.
In the case of cellular frequencies, we have more than 40 possible bands of operation in 4G. Each market uses its own subset and it is possible that the equipment being tested will offer stellar performance in bands in the USA, but it will not be as good in bands in Brazil or Argentina, for example.
It is possible to test cellular technologies (2G, 3G, 4G), Wi-Fi and Bluetooth, in addition to other wireless technologies that are in the frequency range of 600 MHz to 6 GHz.
To carry out these tests, the main international standards recognized for this type of scope are used, such as 3GPP TS 34,114 and 3GPP TS 37,544.