LTE is top of mind for iPhone 5 customers

Computerworld - Apple's iPhone 5 goes on sale Friday, and many buyers are hoping to take advantage of its faster LTE network speeds.

AT&T said Wednesday it added LTE to five large markets this week, listing Seattle, Pittsburgh, metro Detroit, Portland, Ore., and Honolulu. The total number of cities with AT&T's LTE coverage now reaches 72, after Birmingham, Ala, Memphis, Tenn., Sacramento, Calif., Philadelphia, Rochester, N.Y., and Wilmington, Del., were added in recent days.

AT&T also offers HSPA+42 and HSPA +21 speeds, supported by the iPhone 5.

Those two networks are theoretically capable of downlink speeds of 42 Mbps and 21 Mbps respectively, . However, all of the 4G networks in the U.S. tend to have downloads in the 10 Mbps to 15 Mbps in practice because of many variables affecting reception, including the number of users on a single cell tower. Faster LTE is considered ideal for downloading video and for real-time video chat, including FaceTime on the iPhone 5.

Verizon Wireless is the furthest along with LTE, and is expecting to hit 400 markets by year's end, while Sprint hopes to surpass 100 cities by then. Sprint on Wednesday announced it has also sold 1 million LTE devices.

T-Mobile doesn't have the iPhone 5, but is hoping to upgrade to LTE in 2013.

When LTE is not available in a certain area, the iPhone 5 will revert to slower networks. In some phones and with some carriers, switching from LTE to a slower 3G network causes a slight lag in transmission, which analysts said might be an issue to watch out for.

Matt Hamblen covers mobile and wireless, smartphones and other handhelds, and wireless networking for Computerworld. Follow Matt on Twitter at @matthamblen or subscribe to Matt's RSS feed. His email address is mhamblen@computerworld.com.

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