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

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.

The more complex the product and service, the more important it is to test every aspect of network performance and the resultant user experience. In response, operators and manufacturers have collaborated with testers to develop a methodology that fully and consistently evaluates baseband modem performance and antenna design for MIMO operation.

The CTIA - The Wireless Association has recently published a testing standard (Test Plan for 2x2 Downlink MIMO and Transmit Diversity Over-the-Air Performance, Version 1.0) to gauge the Over-the-Air (OTA) performance level of handsets that employ MIMO antennas.

 

Not all mobile devices are created equal

How important is this standard and test procedure? Do devices really show much variation in performance?

To explore the scale of MIMO device performance variances, Signals Research Group has published the results of a study evaluating fifteen commercial mobile MIMO devices across two different OTA labs (Chips and Salsa XX: When Iconic Meets Anechoic, Part II published in Signals Ahead, October 2015). It revealed significant performance differences that would have a noticeable effect on user experience. These include: triple-digit differences in data rates, universal under-performance in at least one frequency band, and a minimal relationship between handset price and reception quality.

This study confirmed the importance of OTA testing in evaluating MIMO device performance. Performance issues in the antenna design will translate into reduced Quality of Experience (QoE), including poor reception, slow downloads, and subpar application performance. For operators, poor QoE becomes a major cause of customer churn, and it forces investment in network infrastructure to compensate for the low quality and reduced capacity.

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