Wave 2 marketing is starting to kick into high-gear, touting Wave 2 as the next big thing and bringing huge advancements in Wi-Fi throughput. In an effort to weed through the hoopla, I started investigating the real-world throughput gains we should expect with Wave 2.

First, I made three main assumptions. 

  1. MU-MIMO is approximately 66% efficient, so if you add a second stream to a different client, throughput only increases 66%.
  1. MU-MIMO improves downstream throughput only, and on average, 50% of today’s Wi-Fi traffic is upstream (use case dependent).
  1. Assume we have an environment where the client devices support an average of 2-streams and achieve an aggregate throughput of y Mbps per AP.

So the question becomes, by using the available streams, how much of the unused airtime will a Wave 2 AP capture and how will that translate to throughput increases?

  1. Assume a 4 stream AP with 25% client support. (2 available streams)( y/2 Mbps / stream) X (50% downstream)( 66% MU-MIMO efficiency)(25% clients) = 0.08y =  8%
  1. Assume a 6 stream AP with 50% client support. (4 available streams) ( y/2 Mbps / stream) (50% downstream) ( 66% MU-MIMO efficiency) (50% clients) = 0.33y = 33%
  1. Assume an 8 stream AP with 75% client support. (6 available streams) ( y/2 Mbps / stream) (50% downstream) ( 66% MU-MIMO efficiency) (75% clients) = 0.74y = 74%

Based on the calculations above, it is clear that until client support is increased above 25%, Wave 2 is not going to bring much of a throughput increase. And since the price of Wave 1 APs will drop, there will be little ROI to be found for early adopters.

At 6 streams and 50% client support, there are clear throughput gains. Some customers can show ROI at this level, especially on high density installs, where 33% throughput gains would be significant. This is probably 18+ months away.

At 8 streams and 75% client support (or 6 streams with 100% client support), the ROI to move to Wave 2 will be very strong for almost all large Wi-Fi installations.

So when will I recommend Wave 2 APs? Not any time soon. And I will add, without question, that the best thing about Wave 2 in the next 12 months is that Wave 1 APs will be going on sale.

 

Dean Zaremba, Free Space Wireless