Three-stream Wi-Fi hits the mark

In 3-stream vs 2-stream tests, 7 MIMO-based access points deliver impressive performance increases

The rapid adoption of 802.11n has become a significant milestone in the history of wireless LANs. The MIMO-based technologies used in most 802.11n systems provide enough throughput, reliability, and rate vs. range performance to effectively remove the last major barriers to the broad adoption of WLANs in the enterprise.

But there is a broad range of options specified in 802.11n, and, consequently, many products with highly varying performance are on the market. A given 802.11n product is usually categorized by the number of spatial streams, with nominally 150Mbps of throughput possible per stream, assuming a 40 MHz. channel and a short guard interval.

Today, 600Mbps, via four streams, is the upper bound of the 802.11n standard, with two-stream implementations at nominally 300Mbps the effective norm. But we're starting to see a significant number of three-stream access points promising up to 450Mbps coming into the market.

Page 4 of 4

Your results will vary

As tempting as it may be, any use of these results to directly compare the performance of the enterprise-class access points tested here should be avoided. Note that we used only a single workload on a single client, a highly unrealistic real-world enterprise scenario, and many other considerations, including system architecture, scalability, capacity, security management features and much more preclude the application of any single figure of merit in this case.

Comparing residential-class and enterprise-class products based on these results would be similarly unrealistic and misleading given wildly diverging sets of capabilities and core missions. Again, our objective was to learn what contribution, if any, might be made by three-stream capability - and we were more than surprised by the results.

Mathias is a principal at Farpoint Group, a wireless advisory firm in Ashland, Mass. He can be reached at craig@farpointgroup.com.

Read more about wireless & mobile in Network World's Wireless & Mobile section.