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Air Time: Running on Empty

The appeal of Wi-Fi is simple: no more Ethernet cables. Freedom from the
shackles of copper wire is not just convenient, it's downright liberating. But
walk into an enterprise conference room, and what do you see? The Cat5
Ethernet cables may be gone, but step carefully, lest you catch your shoes on
someone's power cable snaking its way across the floor. So much for

I recently moved into a newly renovated building on the campus of Syracuse
University. Given my interest in wireless networking, I lobbied hard for a
high-capacity, dual-band WLAN infrastructure. Coupled with a generous helping
of conference rooms, both large and small, the wireless infrastructure is a
critical element in our effort to encourage collaboration. Although the
environment has been well received by students, faculty and staff, everyone has
one major complaint: not enough power outlets. Despite marketing claims of
leading notebook computer manufacturers, most of our wireless-intensive users
can't make it through a typical meeting without plugging their power brick into
the wall.

Limited notebook battery life is often viewed as an inconvenience, but the
nomadic nature of notebook users makes the situation tolerable. For users of
emerging Wi-Fi-enabled VoIP and smartphones--so-called converged mobile
devices--however, limited battery life is an absolute showstopper. That problem
is getting some much-needed industry attention, most recently in the form of a
new Power Save Certification from the Wi-Fi Alliance. This new element is part
of the alliance's broader WMM (Wi-Fi Multimedia) program, which also
addresses key issues related to quality of service.

Though the original 802.11 standard included provisions for conserving battery
power, the system has not been widely adopted, in large part because its
architecture results in a significant performance hit and additional network
overhead. In addition, legacy power-savings mode is controlled by network
interface drivers rather than by applications, a one-size-fits-none approach.
For converged devices supporting real-time voice applications with strict
latency requirements, legacy 802.11 power-savings technology simply isn't