Over-the-Air testing is vital if MIMO is to deliver good QoE – the smaller they get, the more gets packed into them…: Page 3 of 4

November 21, 2016 //By David Garrison, Spirent, Senior Director Wireless
Mobile devices and networks are growing ever more complex, not only in terms of features but also in the underlying technologies needed to support those features – technologies such as MIMO (Multi-Input Multi-Output) that require each tiny handset to contain not one but multiple radio antennas.

Introducing the CTIA MIMO OTA Test Plan Version 1.0

An official CTIA MIMO OTA test must be conducted in an anechoic chamber with 8 dual- polarized probes. The lab validation tests must include ripple test, range calibration, and Signal-to-Interference Ratio (SIR) validation, to ensure the quality of the chamber setup and that evaluation is conducted at the correct power levels without extraneous signal interference. Definitions of measurement uncertainty elements are provided, and an overall measurement uncertainty limit is defined.

All the channel model validation procedures are defined for key items such as: Power Delay Profile (PDP), Doppler/temporal correlation, and spatial correlation. Finally, cross polarization is examined to check if the signal arrives at the device in a way which verifies that the amount of signal, in both vertical and horizontal polarization, is in accordance with the expected model. These channel model validation tests are typically performed by the system provider.

Testing can only take place once the setup has been shown to meet CTIA standards. Performance is measured in terms of MIMO Average Radiated SIR Sensitivity (MARSS). Average SIR over a set of orientations within the test environment provides a more representative assessment of user experience. CTIA also provides reporting templates to ensure that test results are presented in a consistent format.

Further detail on the OTA test procedure is available in a Spirent white paper Ensuring MIMO Device Performance with Over-the-Air Testing.

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