Over the last few years, Multiple-Input/Multiple-Output (MIMO) technology has been regarded as a key leverage that wireless service providers can exploit for boosting mobile network capacity.

The basic theory of MIMO relies on the usage of multiple antenna elements at both the radio link ends in order to fulfill the transmission and reception of parallel data streams.

This is generally referred as “spatial multiplexing gain.” 

From a performance perspective, MIMO technology finds a perfect field of application in in-building solutions such as distributed antenna systems (DAS).

In particular, several field measurements have demonstrated that capacity improvements versus single antenna schemes are quite substantial.

The other side of the coin is the equipment and installation costs associated to in-building MIMO DAS deployments, which now have to support multiple RF branches.

In practice, a 2x2 MIMO DAS requires double the infrastructure in terms of antennas, cabling and active equipment.

LTE specs currently have a gap for Interleaved MIMO in the sense that there are no defined conformance tests for mobile terminals in order to support this alternative MIMO scheme.

Ameison has actively promoted Interleaved MIMO within 3GPP as an effective solution to address the cost concerns of wireless service providers.