Validation of the Decomposition Method for Fast MIMO Over-the-Air Measurements

Over-the-air (OTA) throughput tests of
wireless multiple-input multiple-output (MIMO) devices
are an important tool for network operators and
manufacturers. The user equipment (UE) is placed
in an anechoic chamber and a random fading process
is emulated by a base-station emulator (BSE).
The antenna characteristic of the UE is taken into
account by sampling the sphere around the UE with
the BSE test antenna at a large number of positions.
For low-variance throughput results, long measurement
intervals over many fading realizations are required,
leading to long and expensive measurement periods in
an anechoic chamber.
To speed up the OTA test, we analyze the Decomposition
Method (DM). The DM splits the throughput
measurement into two parts: (1) a receiver algorithm
performance tests taking the fading process into account
and (2) an antenna performance test without
fading process emulation. Both results are combined
into a single throughput estimate. The DM allows for
a measurement time reduction of more than one order
of magnitude. We provide an analytic and numerical
analysis as well as measurements. Our detailed results
show the validity of the DM in all practical settings.