editor's blog
Subscribe Now

MIMO: Hardware or Software?

A while back we covered CEVA’s move to multicore for their communications-oriented XC architecture. One of the motivating elements was the complexity of requirements for features like MIMO, the ability to use more than one antenna – and multiple channels formed by the product of the number of sending and receiving antennas. They say that using a software approach provides the flexibility needed for the variety of options, that there are too many differences between options to implement in hardware: there would be too much unshared hardware, and it would be inefficient.

Sounds reasonable. But then came a completely separate announcement from Quantenna. They’re also doing MIMO, but in hardware. They can handle up to 4×4 MIMO (that is, 4 antennas sending, 4 receiving; 16 channels). And they say that it’s not reasonable to expect to be able to meet the performance requirements without doing it in hardware.

Both companies seem to agree on the complexity of the standards they’re implementing. The thing about such WiFi communication is that the environment is constantly changing, and you have to constantly re-evaluate which channels are working best and where to send things. This re-optimization is checked every 100 ms.

In fact, Quantenna says that, if the radar band is unpopulated, it can also be used, although they claim that most boxes don’t take advantage of this, remaining within the crowded non-radar portion, even though the radar portion has the bulk of the available bandwidth.

There is also beam-forming to be done – including “blind” beam-forming, where only one end of the channel can do it. Channel stability has to be rock solid since there’s no buffering for streaming video. Equalization has to be optimized. And in a higher layer, there’s quality-of-service (QoS) for video.

And most of this isn’t established at design time; it’s a constant real-time re-jiggering of parameters to keep things working as efficiently as possible. And it has to work alongside the earlier 802.11n and below standards. And Quantenna says they can handle all of this in hardware, without blowing the silicon budget.

You can imagine that being able to do it in software might be quite convenient and space-efficient. You can also imagine that hardware would provide much higher performance. So which is best?

Rather than get into the middle of adjudicating this myself, I offer both sides the opportunity to state their cases in the comments below. And any of the rest of you that have something constructive to contribute to the discussion, please do.

Meanwhile, you can get more details on Quantenna’s announcement in their release.

Leave a Reply

featured blogs
Aug 14, 2018
Introducing the culmination of months of handwork and collaboration. The Hitchhikers Guide to PCB Design is a play off the original Douglas Adams novel and contains over 100 pages of contains......
Aug 14, 2018
Harold Wilson, then Britain's Prime-minister, once said, "A week is a long time in politics." Well, a year is a long time in the current automotive market. I've written quite a bit about the market in general (most recently about the Chinese market, see my...
Aug 13, 2018
Last week at Intel'€™s Data-Centric Innovations Conference, a rude attendee sitting a few seats away from me in the auditorium persisted in using his mobile phone during presentations. He attempted to muffle his voice by covering his mouth with his hand but only succeeded i...
Aug 9, 2018
In July we rolled out several new content updates to the website, as well as a brand new streamlined checkout experience. We also made some updates to the recently released FSE locator tool to make it far easier to find your local Samtec FSE. Here are the major web updates fo...
Jul 30, 2018
As discussed in part 1 of this blog post, each instance of an Achronix Speedcore eFPGA in your ASIC or SoC design must be configured after the system powers up because Speedcore eFPGAs employ nonvolatile SRAM technology to store its configuration bits. The time required to pr...