Data Communication in MIMO Radar Systems

In a previous blog post, I wrote about how the MicroTCA standard has a better scalability than the AdvancedTCA standard. I focused mainly on how the different parts of a MicroTCA system can easily be modified (added, removed, changed) to address not only MIMO radar applications but also other applications in many different fields.

Being able to adapt your MicroTCA system to easily change or add more I/Os requires an adaptable communication system. In the MIMO radar system I used as an example, this communication adaptability is provided by two key components, the backplane of the MicroTCA chassis and the MicroTCA Carrier Hubs (MCHs).

In this post, I will briefly discuss these two components of the system and the way they connect the different parts together.

As a refresher, the photo below shows a MicroTCA MIMO radar system, with labels indicating its different modules:

MicroTCA_MIMO_radar_system

Figure 1: MicroTCA MIMO radar system

 

Basics of the AMC Backplane

The AMC standard defines 21 ports that can be used for different communication protocols. Each port supports data up to 10 Gbps. Depending of the chassis, these ports can be connected or not, in a point-to-point way or through an MCH. It is important to note that the connectivity of the backplane of a MicroTCA chassis is not standard and there can be as many different backplane configurations as there are chassis. When choosing a MicroTCA chassis on which to build your own system, it is absolutely crucial to make sure all the connections your system needs are present.

Here is a more detailed list of the ports available in an AMC backplane and their usage:

  • Port 0-3 – Common Options

– Port 0: GigE

– Port 1: GigE or PCIe

– Ports 2-3: SATA, SAS

  • Ports 4-7 – Fat Pipes

– Can be used for PCIe, 10GbE or SRIO communication

  • Ports 8-11 – Extended Fat Pipes

– Can be used for PCIe, 10GbE or SRIO communication

  • Ports 12-20 – Extended Options

 

Communication in Our MIMO Radar System

As I mentioned, the connectivity of a MicroTCA chassis backplane is very variable. The backplane presented in the diagram below is specific to the MIMO radar system we used as an example. Following the figure are descriptions of the different connections.

Backplane_MIMO_radar

Figure 2: Backplane MIMO radar

 

SATA (in blue)

The SATA connection is often a point-to-point connection between specific slots. In our example system, slots 0 and 1 are directly connected through the ports 2 and 3. This means that someone who wants to connect a SATA storage device to an AMC CPU blade in this particular chassis configuration must place these two devices in these two specific slots.

 

PCIe (in red)

In contrast to the SATA connections of this system that are of the point-to-point type, the PCIe links depend on the use of two MCHs. The MCHs are responsible for managing the interconnections of the system and make sure that all the AMC devices connected on the PCIe ports (ports 4-7 in this system) can communicate with each other. Two separate PCIe buses are present in this system: one handles the output portion of the system and the other the input portion of the system. Note that for each one of these buses, an external root-complex device must be present to take care of the enumeration.

 

GigE (in green)

Each AMC slot of this system is connected to a single MCH that handles all the switching. Typically, since its throughput is lower than PCIe, this link is the one used by the operator to configure the devices prior to launching the application and to control the operation of the system. PCIe is more often dedicated to data exchanges.

 

Conclusion

Through their backplane and with the help of MCHs, MicroTCA chassis provide the communication links needed for complex systems to function.

The more common communication links used are SATA for data storage, GigE for control, and some data exchanges and PCIe for high throughput data exchanges. Other links between the AMC devices could exist. For example, some devices could use ports 17 to 20 that are extended options port to implement a point-to-point Aurora link in a specific chassis that has this connection available.

Special care must be taken when choosing a chassis for an AMC system since the connections on the backplane are very variable; all the interconnections the system needs must be present.