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Recycled spectrum to help realize global LTE roaming

Mikael Ricknäs, IDG-News-Service:Stockholm-Bureau | April 15, 2011
As more LTE networks go live across the globe, wireless operators have started planning to offer data roaming, and reusing spectrum is seen as one of the best chances of getting worldwide coverage, according to speakers at the LTE Forum conference this week in Stockholm.

To free up the spectrum, operators would first have to move the voice traffic from GSM to 3G. But how long it will take before LTE on 1.8GHz reaches critical mass depends on regulators and courts, as much as the operators themselves.

For operators to use the 1.8GHZ band for LTE, however, regulators have to give them the go-ahead. This might provoke complaints from competing operators that lack spectrum in that band. In Sweden, the local regulator's decision was appealed, and is now being handled by the Administrative Court of Appeals.

In the end, despite the promise of the 1.8GHz band, no one frequency used for LTE is likely to offer global roaming. Products will have to support multiple frequencies. For example, Huawei is working on a modem that will support a combination of the 800MHz, 900MHz, 1.8GHz, 2.1GHz and 2.6GHz band on a mix of GSM, 3G and LTE networks.

That modem would still leave users without LTE coverage in the U.S. -- for that, 700MHz also has to be added to the list. Suazo compares the current situation for LTE roaming to the GSM phone market before the arrival of "world phones."

Operators are keeping mum on when LTE roaming will become available. Meanwhile, users will have to rely on HSPA (High-Speed Packet Access) for data roaming. But some operators have started tests to ensure that their LTE networks are ready, including TeliaSonera.

"For data roaming to work, there are a number of interfaces that have to be able to talk with each other, and we have tested that on the vendors we use: Ericsson, Huawei and Nokia Siemens ... so technically there are no barriers," said Tommy Ljunggren, vice president of system development at TeliaSonera.

But roaming involves far more than just equipment. Operators also have to sign new roaming agreements, and agree on a business model, according to Ljunggren.

Part of the business model could be sending subscribers' data sessions directly to the Internet via the visited network, using a feature called Local Breakout, instead of sending the traffic back home and then onto the Internet, which is what operators do today. That would be a boon to latency-sensitive applications, Ljunggren said.

So far, data roaming has been very expensive, especially for doing more than just checking emails.

"The industry has to do something about the roaming setup, that's for sure. We can't continue to have the current prices. A few operators are doing something, but I think it is moving a little too slow," said Ljunggren.

 

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