As the world's carriers call for agreement on enough LTE frequencies to make roaming a reality, the technology's backers in North and South America are pushing for a single band that data-hungry travelers could use across the Western Hemisphere.
To make roaming practical, enough countries have to agree to use the same band for LTE, or at least agree to embrace a small number of frequencies across enough countries that phone makers want to include them all. The spectrum bands assigned to LTE are currently too fragmented to make that work, carrier executives lamented at a Mobile World Congress keynote session on Monday morning. The launch of the iPhone 5 with a limited set of LTE bands helped to put the roaming problem in the spotlight.
There is some hope for LTE roaming among countries in North and South America, but the frequencies don't quite line up yet, according to Chris Pearson, president of 4G Americas, the regional trade group for LTE.
"Are we concerned about fragmentation? Yes. So what we're doing is working with all these governments and the U.S. to say how important it is," Pearson said in an interview Monday.
One of the bands being used for LTE in the U.S., the AWS (Advanced Wireless Services) band, is nearly the same as a band recommended by the Inter-American Telecommunication Commission. That group, abbreviated as Citel, is the telecommunication arm of the Organization of American States, so it holds some sway over governments' spectrum regulations around the region.
The AWS band is made up of two blocks, one from 1710MHz to 1755MHz and the other from 2110Mhz to 2155MHz. One is intended for downstream traffic to users and one for upstream traffic back to the network. Canada uses the same AWS band as the U.S.
The band recommended by the OAS covers the same blocks, but with 25MHz of additional spectrum on the top end of each: The lower block goes to 1780MHz and the upper block to 2180MHz.
LTE is growing rapidly in Latin America, with four networks online at the end of 2011 and 14 by the end of last year, said Erasmo Rojas, director of Latin America and the Caribbean for 4G Americas. There's fragmentation within Latin America itself, with five different bands represented among those LTE networks. But the band that nearly matches AWS has been widely adopted, with networks live in Mexico and Chile, auctions already completed in Peru and Paraguay, and the spectrum blocked off for later auctions in several other countries, Rojas said.
If those blocks lined up perfectly, device makers could build it in to all the LTE products they sold across the region, and carriers that used that band could offer LTE roaming around much of North and South America. But the extra 25MHz that the OAS supports is already called for in the U.S., Pearson said.
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