AT&T's 3G upgrades to improve iPhone service

AT&T is upgrading its network and using 850MHz spectrum to beef up its 3G wireless network, which should help alleviate dropped calls and slow network connections for iPhone 3G and iPhone 3G S users.

Apple said this week that it sold more than a million of the iPhone 3G S model worldwide this past weekend after the phone went on sale Friday. Exactly how many of those phones were activated on AT&T's network in the U.S. isn't yet known, but the addition of more data intensive iPhones is likely to put a strain on the carrier's network.

That said, AT&T spokesman Mark Siegel told the blog Gearlog on Tuesday that the company is ready for the onslaught of new iPhone users. One of the things it has been doing to prepare is upgrading its network so that it can offer 3G wireless service using its 850MHz spectrum licenses. For the most part, AT&T has been using spectrum in the 1900 MHz band to deliver its 3G services, which have become saturated, Gearlog explains. This means that as AT&T sells more 3G devices, such as the iPhone, it has been cramming more users into an ever more crowded spectrum band.

This could explain why some users have complained of dropped calls and slow Net connections using the iPhone 3G, an issue that CNET News pointed out nearly a year ago after the iPhone 3G was launched. The problem has been particularly acute in large cities, such as New York and San Francisco, where there is a concentrated base of iPhone users and where the 1900MHz spectrum is predominant.

Siegel says that upgrading equipment to allow AT&T to use its 850MHz spectrum for 3G services should help relieve some of the congestion issues. Because the 850MHz spectrum is at the low end of the frequency band, it is able to travel longer distances and penetrate walls more easily than signals on the 1900MHz band.

When asked about problems with dropped calls for iPhone 3G users a year ago, Siegel told CNET News that the company had been working to expand the portion of its 3G network that runs on the 850MHz band. Back then he downplayed the need for adding 850MHz spectrum for 3G services by saying that it "doesn't mean you can't get a good experience on 1900MHz."

Now Siegel thinks that adding 850MHz will make a big improvement, according to the Gearlog story.

"The 850, when it's turned on in individual markets, people notice a big difference," he is quoted as saying.

In addition to adding 850MHz 3G service, AT&T has also been making other improvements to its network, such as upgrading to the next iteration of HSDPA technology, which is expected to double download speeds on AT&T's network.