The MTCA.4 chassis architecture of the TitanMIMO-4 enables mesh connection of the FPGA subgroups. In this way, processing performance could be upgraded by using the subgroups as processing subunits.

The figure below shows a sample of mesh-based connections for the base system. Each set of eight miniSAS connectors are attached to a Perseus 6111 card by the RTM connectors. Out of these eight connectors, seven are active. One may see that many miniSAS connectors are left unconnected and can easily imagine using them to connect the Perseus 6111 in a mesh. 

Massive MIMO Backplane Mesh Topology

Click image to expand

In our example, we have grouped the Perseus 6111 boards into subgroups. For example the fourth Perseus 6111 from the top left corner is a subgroup master and receives three connections from the first three Perseus 6111. The fourth connector on the fourth Perseus 6111 is used to link to the system master Perseus 6113.

The yellow connections depict how we can connect the boards in a mesh. In the top-right subgroup, every Perseus is connected to every subgroup member in a way that all Virtex-6 FPGAs can exchange data at a 16 Gbps rate.