Interop panel: Finally finalizing 802.11n
You may think the 802.11n Wi-Fi networking standard is already here. The fact is, equipment manufacturers have been relying on drafts. At last, the final draft is on its way, and an Interop panel discussed its implications Wednesday.
The now emerging IEEE 802.11n Wi-Fi standard will add some major new twists to Wi-Fi, or in many cases, finalize some of the twists manufacturers have already begun implementing while waiting for the finalized draft. Some of the most important of these changes will include three modes of operation and two frequency ranges, speakers said at the Interop conference here Wednesday.
Although the IEEE has not yet approved the final 802.11n standard, some wireless devices, such as routers, are already available that comply with the emerging specification.
The three modes of operation encompass “802.11n only, 802.11b/g only, and mixed mode,” noted Paul DeBeasi, a senior analyst at the Burton Group. The standard also supports both the 2.4 GHz and 5 GHz frequency ranges.
Underneath the covers, the new standard — with is backwards-compatible with 802.11b/g — introduces new technologies that include multiple-input/multiple output (MIMO) and channel-bonding/40 MHz operation. MIMO is aimed at using the diversity of multipath signals — or reflected signals that arrive at the receiver after the line of sight (LOS) signal has been received, to increase the receiver’s ability to recover the message information.
“MIMO will do a lot to improve reliability and predictability for 802.11b/g transmissions,” asserted Chris Kozup, senior manager, mobility solutions marketing, at Cisco, another speaker.
Channel bonding, on the other hand, is supposed to increase the amount of data that can be sent by utilizing two separate non-overlapping channels for transmission.
By and large, the panel agreed that the standard’s “802.11n only” mode isn’t likely to play much of a role in the near future.
Some also contended that deployments done in “mixed mode” are likely to suffer from performance hits. “It’ll definitely slow things down,” predicted Wade Williamson, director of product management for AirMagnet.
One way to solve this problem will be to section off Wi-Fi networks into “801.11b/g only” and “802.11n” segments, suggested another speaker.
As for the two frequency ranges, when should the newly supported 5 GHz spectrum be used? The choice of spectrum depends in large measure on which frequency range is most available in a specific environment, pointed out Kevin Goulet, senior director, product marketing, Motorola Enterprise WLAN Division.
Yet speakers argued that, with the 2.4 GHz band already saturated, the newly supported 5 GHz will allow for faster operations.
Cisco’s Kozup proposed that, in order to full what he called “the promise of 802.11n,” devices will need DHS certification for using radar channels in the 5 GHz band. Otherwise, Wi-Fi devices operating in that spectrum shift channels in the presence of radar.
Cisco and Xirrus are the only vendors certified to use these radar channels so far, contended Kurt Sauter, Xirrus’ director of product marketing.