To function properly, WMM Power Save needs to be implemented on APs
(access points), in wireless device drivers and within applications running on
those devices. Wireless stations and APs negotiate power save when the
station associates with the AP. The system leverages the priority queues
defined in WMM and 802.11e while also maintaining backward compatibility with
legacy 802.11 power-savings mode.
Because WMM Power Save requires tight integration between applications and
wireless drivers, it is likely that initial applications will focus on
application-specific mobile devices, especially VoIP phones. The Wi-Fi Alliance
suggests that such devices will realize enhanced power efficiency of between 15
and 40 percent. However, to be successful, this "standard" will need to be
broadly supported by chipset and AP manufacturers. The Wi-Fi Alliance is off to
a good start in that regard, with a number of products already certified. The
list includes AP reference designs from Atheros and Broadcom, Cisco's Model
1231 abg AP and several client radio modules from Broadcom, Conexant, Ralink
and Winbond.
Purists might argue that this is yet another example of an industry association
encroaching on turf that traditionally has been the domain of standards bodies.
To a certain extent, that's true. But as basic 802.11 functionality becomes a
commodity in the market, you don't really need the Wi-Fi Certified stamp of
approval to ensure basic interoperability.
Extending beyond the basics has never been an easy task for the IEEE,
especially when issues relate to application-layer functionality. The Wi-Fi
Alliance continues to assert its relevance by striving to meet the needs of its
membership, including the many companies that see voice as a compelling
WLAN application. By making WMM Power Save an optional element of the
certification, the alliance isn't forcing companies to adopt this technology. But
by offering such a certification, the alliance is advancing important capabilities
that will provide enterprise IT professionals with more choices. That's good for
the industry.
