As many of you know, Nutaq is in the process of creating products that address the massive MIMO market. Our existing platforms are already great for this field of work, but as the number of channels increase in a system, the cost of that system also increases significantly. One solution for keeping the costs as low as possible is to increase the number of channels that can be processed on the same processing unit (the quantity of these parts is often one of the major cost drivers for massive MIMO systems).

We already made a move in this direction when we created our in-house FPGA mezzanine card (FMC) double-stack specification. Using FMC double-stacks, we are able to double the quantity of analog-digital converter (ADC) or digital-analog converter (DAC) channels that are connected to a processing unit. The processing unit in this case is an FMC carrier (our Perseus601x AMC) that includes a Virtex-6 FPGA. Using a stack of 2 MI125 ADC FMCs results in 32 ADC channels that can be connected to a single Virtex-6 FPGA, with each running at 125 MHz.

We are currently developing an FMC carrier board that will take us another step forwards in channels-per-processing-unit densification: the Perseus611x double-width AMC. This carrier will feature two high-pin count (HPC) FMC connectors and a Virtex-6 FPGA as its processing unit. The Perseus611x will support both the LX550 and SX475 FPGAs. The end result should look similar to the following:

This new carrier board will make it possible to create different configurations, including:

–          A system with 64 14-bit ADC channels sampling at 125 MHz (Perseus611x with two MI125-32 stacks)

–          A system with 32 16-bit DAC channels sampling at up to 1 GHz (Perseus611x with two MO1000-16 stacks)

–          A 4×4 radio system (Perseus611x with two Radio420M stacks)

Not only will the Perseus611x enable these systems, but it will also make the intercommunication process between the processing units of an even larger system much easier. A rear transition module (RTM) connector will enable Nutaq's RTM module to connect to the Perseus611x and use up to 7 groups of 4 GTX to communicate with the other nodes of the system. In this blog, Emile describes how a future 100×100 massive MIMO system could be built by connecting Perseus611x nodes together via their respective RTMs. In his system, each node is composed of a Perseus611x, two Radio420M stacks, and a RTM module.