LTE roams into the unknown

John C. Tanner
Telecom Asia

The LTE train has decidedly left the station, with more than 50 operators having launched LTE services to some degree by the start of this year, including eight in Asia Pacific, according to Tolaga Research. And with more and more launches scheduled for 2012 - and with the first LTE handsets unveiled last month at CES - a number of operators are already thinking ahead to the next logical step: roaming. 

And not just for the obvious reasons. LTE's next-gen architecture promises to take data roaming into new territory, with IPX backbones and Diameter signaling enabling local breakout (LBO), in which data traffic is offloaded to the roaming network, rather than being routed first back to the home system. 

To that end, Telstra and its Hong Kong arm CSL demonstrated LBO at November's Mobile Asia Congress event, using Telstra's GRX to transport network signaling using the Diameter protocol between the two networks. Telstra LTE customers roaming on CSL tested apps like HD videoconferencing and video streaming. Result: breaking out data traffic locally enabled roamers to obtain the same speeds as local subscribers and reduce latency 90% compared to 3G roaming.

More to the point, said CSL CTO Christian Daigneault, "With 3G, there is no local breakout because operators want the traffic sent back home to them so that they can charge for it. LTE brings signaling into the picture, so you can still charge for data even with local breakout."

But while LBO opens up some new possibilities for data roaming, it also highlights the inevitable challenges operators face in making LTE roaming a reality. Even the Telstra/CSL demo was just that - a demo, cautioned Daigneault. "If you do it one-to-one like we're doing with Telstra, it's simple. We're basically just showing that it can be done and the benefits you get, such as better latency."    

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