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Katie Fehrenbacher reports at GigaOm that T-Mobile will launch its UMA service Sept. 12: The service will launch in Seattle, the home of the division of T-Mobile that handles Wi-Fi, and perhaps in San Francisco or Chicago. Fehrenbacher notes that UMA handsets might not be allowed to roam onto arbitrary hotspots, perhaps being locked to home units or approved networks. However, she doesn’t pick up on a related fact: that the WMM (Wireless Multimedia) Power Save mode is a necessary feature for both handset and Wi-Fi gateway to ensure that the handsets have decent talk time.
The Nokia 6136 UMA handset—introduced as a proof of concept, as it’s not in use anywhere yet—offers 5.5 hours of talk time via UMA over Wi-Fi, but only if what Nokia labels U-APSD is in the gateway. That’s a long abbreviation for what is more commonly known as WMM Power Save. This mode, found in many current chips, is a function of providing quality of service (QoS), in that it lets handsets reduce unnecessary transmissions and power use, making voice over IP over WLAN practical with a battery-powered handset.
Posted by Glennf at August 16, 2006 1:40 PM
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