Australia’s iPad problem exposes LTE roaming challenge

Stephen Lawson, IDG News Service March 30, 2012

The controversy over Apple’s third-generation iPad not working on Australian LTE networks may be just one sign of problems ahead for international LTE roaming.

Apple said this week it would give refunds to Australian owners of the new iPad if they were disappointed that the tablet couldn’t tap into LTE in that country. The company had come under fire from the ACCC for promoting the third-gen iPad as a 4G device even though it’s not compatible with any Australian LTE networks. Antipodean iPad owners have no option but to rely on 3G.

The case in Australia is indicative of a looming problem for travellers who want fast services in other countries, according to industry analysts: The scramble for spectrum to feed mobile-data appetites is fragmenting the frequencies used for LTE. This is likely to make international roaming harder and relegate some users to slower speeds than they are used to at home.

Growing diversity

In the age of 2G, four bands were enough to qualify a handset as a “world phone”: The 850MHz, 900MHz, 1800MHz and 1900MHz bands were used by most carriers in Europe, Asia and the Americas, or at least those on the globally dominant GSM standard. With 3G, roaming remained fairly simple, at least in Europe, where the European Union prescribed certain bands for the new mobile data technology. But elsewhere in the world, frequencies started to diverge as carriers deployed 3G.

Even now, some 3G subscribers have to fall back to slower standards when they leave their home countries. “It happens all the time,” said analyst Avi Greengart of Current Analysis. For example, a “world phone” equipped for both the CDMA and GSM standards may not leave you stranded without Internet access, but it won’t guarantee consistent speed either, he said.

Two forms of LTE

Adding to the complexity, LTE can be implemented in two different variations, which use either paired spectrum bands (FD or frequency-division) or a unified band (TD or time-division). Which one a carrier uses depends on what kind of frequencies it can get. On top of that, many of the LTE networks set to come on line aren’t built yet, and some of those don’t even have frequencies assigned to them.

“It’s going to be a problem for quite some time,” said Tolaga Research analyst Phil Marshall. There are simply too many possible combinations of LTE variants and locally assigned frequencies to practically sell mobile devices that work with all of them, Marshall said.

While it’s theoretically possible to build a phone, tablet or portable hotspot that could be used on all the LTE networks in the world, the task grows more difficult as more bands are added, Greengart of Current Analysis said. In addition to including many radios, the universal device would need an antenna that could be tuned well to all those LTE frequencies. Plus, high-end handhelds today include Wi-Fi and Bluetooth as well. “That’s an awful lot of frequency bands and antennas,” Greengart said.

Qualcomm says its Gobi 4G/LTE modem chipset supports most of the frequencies being used for LTE, and it is up to manufacturers to decide which bands to support in a given device. The second generation of the chipset will support all the LTE bands, as well as 2G and 3G bands, in the 3GPP standard, Qualcomm said. The greater challenge in designing multi-frequency devices is fitting in the radio-frequency components for each band, according to Qualcomm.

Handset makers and carriers aren’t focused on making devices to run on all the world’s LTE networks, Greengart said. “They’re interested in the least expensive device that works on their network and, in some cases, works on common networks that their customers demand compatibility with.”

The way out

Over time, mobile operators may be able to settle on one or two frequency bands available in most countries to allow LTE roaming, Jarich said. Two possibilities might be TD-LTE in the 2.3GHz or 2.5GHz bands, he said. But a carrier in each country would have to build and operate a network to make that solution a reality.

The better answer for global high-speed roaming may come from Wi-Fi, Jarich said. Cellular carriers and Wi-Fi hotspot operators are working on making it easier for phones and tablets to roam between mobile and Wi-Fi networks worldwide.

Wi-Fi, which runs on unlicensed frequencies that are fairly consistent around the world, with a few exceptions, can offer even more speed than LTE.