Meru's Debut 802.11n Customer Now Using....802.11n

I couldn't help but take notice of the choice of words another publication used to describe the status of Morrisville State College's implementation of 802.11n Meru access points: "shakedown phase". When Meru and Morrisville intitially shared their plans this summer, they had hopes to install 802.11n gear before school started. It was never precisely clear how many 802.11n APs were installed by Labor Day, but the above publication suggests that 720 802.11abg APs were initially deployed that have now been replaced with 802.11n gear. That's slightly short of the 900 APs originally suggested, but perhaps there are a few more locations that still need to be tackled.

One item that's "shaking" out is the power issue. With only 15W of power from their Ethernet switches, only two radio chains are running, instead of three. The publication quotes Meru as stating that there's no difference in data rate or throughput, just reliability. If that's true, then Meru needs to go back to their chipset vendor for a refund.

With fewer radio chains, link reliability will be affected. Link reliability is associated with fade margin, that is, how much tolerance there is in the link to handle signal degradation. Signal degradation can be caused by interference, scattering, multipath, and other environmental effects. Less margin means less tolerance for signal degradation. Higher margin means more tolerance, but it also means a greater throughput capacity as the radios modulate at higher levels.

In any case, more radio chains, on either end, should translate into a higher data throughput rate. Atheros does a nice job of demonstrating the benefits of 3-by-3 over 2-by-3 and 2-by-2. Fanny Mlinarsky, an independent wireless tester, recently performed some tests and compared the rate over range between 3-by-3 and 2-by-2 gear, and the differences are measureable.

It's good to see product plans convert to product announcements that end up installed at customer sites. We're likely to hear about several more substantial 802.11n deployments in 1Q '08 where both customer and vendor expectations will be challenged by reality, and lessons learned and passed on to the more conservative but much larger segment of customers.