The core hardware elements of the TitanMIMO-4 testbed series include:

  1. The central baseband processing engine (available in either single FPGA or distributed cluster FPGA configurations).
  2. The subgroup processing FPGA, used to interface with the RF front ends.
  3. The RF front ends.
  4. The Rear Transition Module which allows for point-to-point inter-FPGA communications.

Central Baseband Processing

The central baseband processing engine of the TitanMIMO-4  has two distinct processing configurations which vary based on the number of FPGAs used for processing.

TitanMIMO-4S: Single FPGA Central Baseband Processing


 
 Perseus 6113

In the case of the single FPGA central processing engine configuration present in the TitanMIMO-4S, the signals exchanged with the upstream/downstream FPGA subgroups all feed into a common master central processing engine, which is Nutaq's Perseus 6113 powered by a large Virtex-6 SX475T. The board also includes two FMC-HPC expansion sites and 4GB of SDRAM memory as well as the FPGA IP cores to read and write into this memory at very high speed. The Perseus 6111 also contains the logic to handle high speed PCIe or GigE data exchange with a host controller CPU for the M.MIMO communication upper layer protocols.

 

TitanMIMO-4D Distributed Cluster FPGA Central Baseband Processing

Kermode-XV6
Kermode-XV6 Distributed FPGA Cluster Block Diagram

The aggregation of all 100×100 channels to a common central processing unit is a must for the initial computational steps of Massive MIMO algorithms. Implementing a Massive MIMO waveform on a set of 100x channels without actual knowledge of the total FPGA resources needed can add significant risk to a fixed, single FPGA baseband processing testbed design.

To give developers a growth path beyond a single central baseband processing element Nutaq has developed the TitanMIMO-4D as a simple extension to the capabilities of the TitanMIMO-4S.

The TitanMIMO-4D is a distributed central baseband processing version where the single FPGA processing of the Perseus 6113 within the TitanMIMO-4S is replaced by a powerful 8xVirtex-6 SX475T FPGA farm, housed on the Kermode-XV6. This is the most powerful AdvancedTCA computing blade ever built, specifically designed to tackle the most demanding signal processing applications.

The Kermode-XV6 is comprised of eight Xilinx Virtex-6 SX475T FPGAs, delivering an outstanding 8.8 TeraMACs solely from their DSP48 dedicated multiply-accumulate engines. Each FPGA interfaces with two DDR-3 SDRAM SODIMM modules, capable of supporting up to 4 GBytes, for an aggregate memory capacity of 64 GBytes.

The Kermode-XV6 supports a mesh ATCA backplane zone 2 and zone 3, with an advanced mesh topology that enables a unique very large virtual FPGA targeting.

 

Subgroup FPGA Processing


 
 Perseus 6111

In both the single & distributed FPGA central processing engine configurations, each subgroup is comprised of multiple double-width Perseus 6111 AMC boards. Each Perseus 6111 has a Virtex-6 LX550T and two FMC-HPC sites that enable connectivity with the radio front-ends.

Each Perseus 6111 can support two 2×2 MIMO Radio 420M boards, yielding four transceivers per AMC. The Perseus 6111 serves as a processing unit as well as an enabler for the Aurora interface through the rear transition modules (RTM). The Perseus 6111 is also equipped with 4GB of SDRAM memory as well as the FPGA IP cores to read and write into this memory at very high speed. The Perseus 6111 also contains the logic to handle the radio front end's functions and set the RF parameters dynamically (frequency, bandwidth, amplification of the signal, high speed AGC, etc.)

 

Radio Front End

 Radio420

The RF front end function of the TitanMIMO-4 is supplied by the Radio 420M. It is a powerful multi-mode software defined radio (SDR) transceiver with two channels (2 Tx and 2 Rx).

The Radio 420M is built around the multi-standard, multi-band Lime Microsystems LMS6002D RF transceiver IC, which supports broadband coverage as well as FDD and TDD full duplex modes of operation.

The front-end converts bandpass to baseband  with no intermediate frequency (IF). I and Q samples are sent to the FPGA on the Perseus 611X for baseband processing or can be transferred to another device.

The Radio 420 is ready-to-use and supplies maximum performance due to its included auto-calibration features (IQ imbalance, DC offset and LO-leakage).

Rear Transition Module


 
 Rear Transition Module

The MicroTCA.4, double-width AMC Rear Transition Module (RTM) for the Perseus 611X expands the I/O capability to levels needed for Massive MIMO testbeds, overcoming the bottlenecks introduced by interfaces such as PCIe. 

On the back plate, 7 miniSAS connectors are available, providing each an Aurora 4x high speed interface capable of handling 16 Gbps.

TitanMIMO-4 Hardware Components

Nutaq's TitanMIMO-4S and TitanMIMO-4D Massive MIMO testbeds are largely comprised of the same hardware components, with the exception of the central baseband processing engine card and the channel count (100×100 for TitanMIMO-4S, 100×100 for TitanMIMO-4D). 

Part

TitanMIMO-4S Units

TitanMIMO-4D Units

Perseus 6111 with LX550T FPGA

25

25

Perseus6113 with SX475T FPGA

1

0
Kermode-XV6 with 8x SX475T FPGA01

Radio420M

50

50

Number of RTM Cards (for miniSAS)

26

25

MTCA.4 chassis

3

3
ATCA chassis01

uTCA Quad core i7

1

1

SSD Additional HDD 600GB

1

1

PCIe Expansion Card

2

3

Clocking distribution components

1

1