Aeroflex 7100 digital radio test set with 4x2 MIMO support

Aeroflex has added support for 4x2 multi-input multi-output (MIMO) to the 7100 digital radio test set for the R&D testing of LTE user equipment. 4x2 MIMO is used to provide improved throughput in good signal conditions and improved resilience in poor signal conditions.

When the signal-to-noise ratio (SNR) at the user equipment is good, the device can make use of spatial multiplexing, where multiple information streams are transmitted simultaneously to improve throughput. When the SNR is poor then transmit diversity is employed. This is where a single information stream is distributed across separately encoded antenna ports to reduce the variations in SNR experienced by the user equipment, thus improving the cell coverage. Measurements are made both at the base station and at the user equipment, and these are used to determine how many streams can be supported in the prevailing signal conditions.

Option 7100-111 is a software licence that enables 4x2 MIMO functionality and can be enabled in the field. Testing can be controlled using either command line interface (CLI) control or programming via Remote API. This software supports 4x2 MIMO measurements on LTE in FDD mode with bandwidths of 10, 15 and 20 MHz. It is planned that 1.4, 3 and 5 MHz bandwidths will be added.

Fading and additive white gaussian noise (AWGN) measurements are supported, using the optional integral fading and AWGN generator, with configurable cross-correlation between streams.

This release of the software supports open loop spatial multiplexing, with closed loop planned to be included in the next release.