1541-4922/06/$25.00 © 2006 IEEE
Published by the IEEE Computer Society
In Brief: Wi-Fi Certification Program Aims to Boost Battery Life
Benjamin Alfonsi
It's often difficult for "non-techies" to grasp exactly how they benefit from many of today's advanced technologies. The Wi-Fi Alliance's (http://www.wi-fi.org) new WMM (Wi-Fi Multimedia) Power Save certification framework, which became fully operational on 5 Dec. 2005, isn't difficult to grasp at all. It addresses the need for expanded battery life in Wi-Fi cell phones and other mobile devices.
Wi-Fi devices used for voice over IP (VoIP) or other real-time applications that are Wi-Fi Certified for WMM Power Save will have a substantially longer battery life, according to analyst Monica Paolini, president of Senza Fili Consulting. Estimating a 15- to 40-percent improvement, Paolini says this is an important consideration for cell phone users who, unlike laptop users, don't usually have a charger with them.
WMM Power Save is an extension of the Wi-Fi Multimedia program, which launched in September 2004 to improve user experience with multimedia and latency-sensitive content. Frank Hanzlik, managing director of the Wi-Fi Alliance, says the combination of WMM and WMM Power Save will prioritize voice traffic and maintain low latency for voice quality while simultaneously saving power.
Consumer market addressed
Paolini says a key reason it has taken so long for Wi-Fi handsets to become available is power consumption. "Wi-Fi was originally developed as a data-centric technology, so the existing power-save mechanisms are optimized for data," she says. "WMM Power Save effectively extends the reach of Wi-Fi, because it brings to the market a power-save mechanism that has been developed for real-time applications and VoIP in particular."
Addressing battery life concerns was simply a matter of keeping up with the market, says Hanzlik. "The decision to focus on power save at this time was driven by the increasing proliferation of Wi-Fi in small form factor devices, such as phones, in which battery life is a major concern," he says.
While both the consumer and enterprise segments are intended to benefit from this initiative, Paolini believes the greater advantage will be for the consumer market. "There is huge demand for Wi-Fi phones and combined Wi-Fi and cellular phones in the market," she says, adding that the few available models primarily target business users. "Eventually you want to get to a point that Wi-Fi becomes as ubiquitous on the phone as it is on laptops, and an advanced power-save mechanism that minimizes power consumption during voice call is needed for that to happen."
Paolini says WMM Power Save will also give further traction to Unlicensed Mobile Access technology, which is aimed primarily at the consumer cellular market. In UMA, the limited choice of handsets is slowing adoption. The alliance's certification program addresses this issue. "The WMM Power Save program will pave the way for affordable cellular and Wi-Fi phones," Paolini says.
Customizing the power mechanism
For the Wi-Fi Alliance, WMM Power Save marks a significant improvement over the legacy IEEE 802.11 power-save program. Hanzlik says WMM Power Save draws on a variety of tools to better manage power consumption. "In legacy power save, the AP beacon timing and the driver decided when to transmit data; in WMM Power Save, the application makes the determination about when to transfer data," he explains. "This enables customization of the power mechanism to the particular application."
Paolini analogizes it to a short snooze. The difference between WMM Power Save and traditional Wi-Fi power-save mechanisms is that WMM Power Save "enables the handset to take micro naps, between one voice frame and the next," she explains. "This effectively increases the amount of time the handset spends in the dozing state, which in turn prolongs battery life."
"The application chooses the time to 'wake up' and receive data packets to maximize power conservation," says Hanzlik. However, he concedes, the power conservation achieved depends on the particular application and how effectively it uses WMM Power Save.
Products Wi-Fi Certified for WMM Power Save can display the WMM Power Save designation on their interoperability certificates. Certified devices include such products as Atheros AR5002AP-2X Access Point, Broadcom AirForce BCM94704AGR Dual-Band 802.11a/g Access Point, Cisco AIR-AP1231G-A-K9 with AIR-RM21A-A-K9, Conexant 802.11a/g PRISM WorldRadio, Marvell Semiconductor 802.11a/b/g WLAN (wireless local area network) router, Ralink 802.11a/g Mini PCI, and Winbond Mini PCI 802.11a/b/g WLAN Client.
If the alliance's plans for the year ahead are any indication, 2006 might be a banner year for Wi-Fi efforts. The alliance is planning to develop formal certification programs for WLAN-enabled mobile phones, voice over Wi-Fi for home and small office environments, and simple configuration of secure home and small office networks.
DOWNLOAD PDF