It's Not Just Performance

Another concern is 802.11n compatibility. For example, can a marketing executive's Apple MacBook Air achieve true 802.11n speeds when it's working with accounting's Cisco Aironet 1250 Series AP? Both currently use draft-2 802.11n. In theory, both will be upgradable to the final standard. And, in theory, they'll be able to talk with each other at sustained speeds of 100Mbps. In theory. A summer 2007 study by Wi-Fi vendor Colubris Networks showed that out of a survey of 200 senior IT professionals, 120 listed compatibility as among their greatest concerns about deploying 802.11n. It would seem they have reason to be concerned.

Of course, anyone who actually uses technology has a healthy wariness when it comes to the latest technology's newest, fastest and greatest claims. Even in the best case for deploying 802.11n, however, its performance claims need to be weighed against other, more obscure financial and technological concerns.

Mulloy pointed out, "One obstacle that affects enterprise 802.11n deployments is power consumption. Most enterprise access points are powered over Ethernet cables. 802.11n uses more power than previous technologies—especially when operating on both the 2.4 and 5 GHz bands. This extra power consumption exceeds the capabilities of today's Power Over Ethernet equipment (which uses a standard called 802.3af)." To support dual-band 802.11n access points, Mulloy said, an IT manager must use two PoE ports or upgrade the entire network to support the new PoE+ standard (802.3at). "That extra cost and hassle can be prohibitive to IT managers deploying wireless."

Schatt agreed. "The power over Ethernet issue also is costly since current switching ports cover 802.3af, which doesn't provide enough power for full utilization of 802.11n on most APs. Some manufacturers, such as Siemens, apparently have figured a way around this issue; others recommend workarounds or the addition of power injectors."

For more on enterprise power consumption concerns, see The Greening of IT.

Another concern is in providing enough bandwidth to the 802.11n routers and APs for them to deliver sufficient speed to their clients. It's generally agreed across the industry that 802.11n WLANs will need Gigabit Ethernet as their backbone to deliver acceptable enterprise performance.

All of this, of course, means one thing: higher installation costs. This leads us back to the beginning: You can't have enough money or a fast-enough Wi-Fi connection. In the case of near-future 802.11n deployments, many businesses really might not be able to get enough of either one.