MIMO OTA testing using CTIA’s recommendations
LTE-Advanced technology features such as MIMO1 help to improve the radio performance of future mobile devices and enable end-users to access a truly mobile broadband experience with very fast data rates. The increasingly complex mobile devices are leading to a need for more extensive testing prior to market launch.
MIMO Over-the-Air2 (OTA)testing enables test houses, manufacturers and mobile operators to verify the performance of a mobile device equipped with multiple antennas. This type of performance testing is used to assess the end user experience when accessing data services on a mobile device by replicating conditions similar to how the device is used in the real world and in different environments including urban, suburban, rural and indoor environments.
There are mainly two types of MIMO OTA testing; one that uses an anechoic chamber in combination with a channel emulator and another that uses a reverberation chamber, also in combination with a channel emulator. Recently, the industry has moved forward to ensure the most appropriate type of MIMO OTA testing is used in order to accurately assess the performance of a device.
CTIA recommends that MIMO OTA testing should be performed using a multi-probe (Multiple Cluster) methodology (AC-MC) in an anechoic chamber, together with a channel emulator. It also recommends for transmit diversity testing,associated with low throughput and low-latency use cases such as VoLTE,to be performed using either the multi-probe methodology (‘AC-MC’) or an ‘RC+CE’ test methodology, which uses a reverberation chamber together with a channel emulator.
MIMO OTA testing also includes the testing of larger devices such as tablets and laptops, which requires a ring of 16 antennas.Since each antenna requires signals from two channel emulator ports, the channel emulator will,in such cases,need to support up to 32 channels. Test set-up is much simpler and quicker with a 32 port channel emulator compared to a 2 x 16 port channel emulator.
Anite’schannel emulator (Propsim F32) offerssuperior channel emulation capacity in a single unit and is fully compliant with CTIA’s MIMO OTA performance test plans. This has led many independent test laboratories in China, Taiwan, Europe and US to select Anite as their MIMO OTA testing partner.
1MIMO (Multiple Input Multiple Output) technology uses antenna configurations where both the base station and the device are equipped with multiple transmit/receive antennas.
2Over-the-Air testing is conducted in the laboratory and involves testing a wireless device without any connected cables, thereby incorporating the device antenna performance.