From B/G to N: is A getting in between?

In discussions with vendors and users regarding possibly migration strategies to 802.11n, the question has come up more than once how to deal with 802.11a. For organizations that never deployed dual-band access points this won???t be a problem, but surveys and anecdotal reports suggest that perhaps up to 50% of enterprises have a dual-mode deployment (802.11b/g at 2.4 GHz and 802.11a at 5 GHz). Here???s a brief overview of 802.11a intentions and perspective: ??? A 2004 Jupiter Research poll asking ???Which of the following describes your current or planned access point environment across all locations???? received a meager 13.3% response for 802.11a (although 802.11a/b/g had almost 70%). ??? A Rutberg research note on Networld and Interop 2004 said that:

??? A 2005 NWC reader poll asked how important certain WLAN standards were to the organization's deployment plans over the next 3 years. Of the four letter standards listed (802.11a, b, g, and n), 802.11a scored the lowest at 3.5 and 802.11n, still in the earliest stages, garnered 4.8 out of 7. ??? A 2006 NWC reader survey repeated the question, and 802.11a received yet again the lowest score, 3.7 out of 7.

Here are some measurements regarding 802.11a usage from analyst reports: ??? A 2002 Giga Information Group survey documented that only 7% of WLANs had 802.11a installed. ??? A 2006 Gartner report based on a 2005 survey showed that around 37% of respondents supported 802.11a/b/g and less than 10% supported 802.11a (multiple responses allowed, so the results are not additive). ??? In a Kubernan ???2007 Wireless LAN State-of-the-Market Report???, 50% of those surveyed said that 802.11a was in use at their organization. Twenty-eight percent of the respondents said that they had no plans of using 802.11a moving forward.

What???s interesting is that despite the pessimism and poor initial success, organizations that have deployed 802.11a are discovering, to their delight, that the percentage of 802.11a connections has been climbing from single into double-digits. Xirrus recently issued a press release regarding the installation of their gear at the ITU International Conference Center in Geneva. During a recent event that customer averaged just a bit higher than 33% 802.11a connections. In a briefing at Interop Las Vegas earlier this year, Xirrus shared that their customers were seeing 30 to 50% of their wireless clients using 802.11a.

Syracuse University, home to one of Network Computing???s labs, has recorded steady growth in 802.11a usage. In the spring of 2006 it was just over 10%; a year later, in the spring of 2007 it hovered between 20 to 25%. This fall it has seen 35 to 40% 802.11a usage, sometimes exceeding 50%.A contact from Cisco???s Wireless Networking Business unit also shared that approximately 60% of their own internal connections now use 802.11a.

The source of the growth is pretty clear ??? Intel???s success with its Centrino products. With the introduction of the dual-band 2915ABG more than two years ago, followed by of 3945ABG last year, most laptops now ship with dual-band Wi-Fi. Considering that most laptops have a three to four year lifecycle, it hasn???t taken long for a non-trivial percentage of the Wi-Fi client base to support 802.11a. And this year Intel added the 4965ABGN adds 802.11n draft 2.0 support. Sooner rather than later the incremental cost for 802.11n support will make the 4965ABGN the de facto chipset for enterprise notebooks, and then soon afterwards, consumer laptops.

So if an organization is looking forward to a greenfield deployment of 802.11n at 5 GHz, how will it deal with the rising number of clients using 802.11a? Stay tuned.