Screaming MIMO

New 802.11n Draft 2 products targeted at the small-office/home-office market show a dramatic improvement in interoperability and a slight improvement in throughput over the Draft 1 products we tested last summer.

Throughput results were well below the theoretical maximum of 300Mbps, but many products did exceed 100Mbps, which means they deliver significantly better performance than 802.11g products at prices that aren't much higher.

With major vendors, such as Cisco and Meru Networks, beginning to ship enterprise-grade MIMO gear (which we plan to test later this year), Farpoint Group (the wireless networking consultancy that conducted this round of testing) predicts that a massive shift to 802.11n is going to materialize over the next year, with complete dominance of the market by this technology by early 2009.

When we tested 802.11n gear last year, we found a disappointingly broad range of variability in throughput and generally poor interoperability among so-called "Draft 1-compliant" products -- not an entirely unexpected result given the lack of any form of third-party interoperability certification.

This year, we tested wireless throughput and interoperability for residential/SOHO/small-business products based on Draft 2 of the IEEE 802.11n wireless LAN (WLAN) standard and certified by the Wi-Fi Alliance under its new Draft-n program.

This year's products -- representing the latest from Belkin, D-Link, Linksys, Netgear and SMC -- with a few exceptions, did much better in the interoperability department, and we occasionally saw performance better than the best of last year's crop. It's clear, though, that we still have a long way to go to get to interoperability levels on a par with those common in 802.11g and 802.11a deployments.

In a nutshell, over the course of testing, we found:

* Excellent throughput performance in both the Linksys and SMC products, though each excelled on different tests -- Linksys in TCP, with 97.5Mbps, and SMC in User Datagram Protocol (UDP), with an amazing 122.7Mbps. Interestingly, Linksys only got to 67.33Mbps on UDP, and SMC produced a subpar 41.82Mbps on TCP.

Netgear came in second in UDP and third in TCP, and Belkin has some work to do in the driver department -- the Belkin client had a hard time maintaining connectivity with any of the routers, and couldn't complete the UDP tests.

* The Linksys router showed very good TCP interoperability with all the clients we tested and led the pack with an average across all clients of 79Mbps -- a good 25Mbps ahead of its nearest competitor. On the other end of the scale, the D-Link router averaged 26.9Mbps, and only 36.3Mbps when paired with its own client. The best average client performance across all routers was Netgear, with 62.2Mbps, and at the other end was SMC, with only 35.8Mbps. The interoperability problems we discovered last year are clearly not yet solved -- but they also didn't affect our overall scoring, as heterogeneous configurations are not the preferred solution in a SoHo environment.

* Netgear took top honors in video reception range-limit tests, demonstrating the ability to transmit watchable video at an astounding 245 feet. But Belkin and SMC weren't far behind at 225 feet.

Why the variability in results, both between product pairings and in the individual benchmark runs? There are major differences in the designs of the systems tested, and especially in the WLAN chipsets employed. Drivers also make a huge difference in performance and reliability. Combine all of this with the vagaries of radio and wireless communications in general, and a high degree of variability in performance can be expected. We also need to point out that all of the results are well below the theoretical maximum of 300Mbps for these products -- and, while technically correct, we still question the wisdom of misleading unsophisticated consumers with what are nothing more than engineering specs.