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Qualcomm tackling faster LTE, but how fast is up for debate

Stephen Lawson | Nov. 22, 2013
New Qualcomm chips can work with LTE networks using large-scale carrier aggregation.

Mobile device chips coming next year from Qualcomm will be able to use wide spectrum bands that carriers are beginning to patch together with new technology, but its lofty performance claims need to be taken with a grain of salt.

Qualcomm says its new modem and transceiver chips can take advantage of spectrum-bundling capability for theoretical speeds as high as 300Mbps. Several mobile operators are already using or preparing for those techniques, but the actual speed a subscriber could get with all that spectrum will depend on a lot of factors.

The silicon heavy-hitter announced the two chips on Wednesday. They're due to ship in sample quantities early next year and go into the company's RF360 Front End Solution. The new chips, called the Gobi 9x35 modem and the WTR3925 RF (radio frequency) transceiver, are designed to work with LTE networks that combine multiple bands of spectrum for higher speed.

Qualcomm has supported that network technique, called carrier aggregation, in previous chips. But the latest silicon can support aggregation of as much as 40MHz of spectrum, which could deliver the theoretical top speed of 300Mbps, according to Qualcomm.

Carrier aggregation is part of LTE-Advanced, a set of upgrades to the 4G standard coming over the next few years. By combining multiple bands of spectrum into one virtual band, mobile operators can achieve higher speeds and take advantage of all the frequencies they control. Qualcomm says its new silicon supports any method of combining 5MHz, 10MHz, 15MHz and 20MHz chunks of spectrum that is approved by the 3GPP, which oversees LTE.

Each advance in mobile networks requires a corresponding improvement in the devices that run over them, or the gains will mean nothing. In that sense, Qualcomm's new chips are well timed. Carrier aggregation is just beginning to emerge.

Verizon Wireless is already combining two 20MHz channels in some markets using carrier aggregation, according to spokesman Tom Pica. Sprint expects to do the same starting late next year using spectrum it acquired through its Clearwire purchase. By late 2015, it plans to pull together three 20MHz bands of that spectrum. AT&T and T-Mobile USA could not immediately respond to questions about carrier aggregation, but both are expected to take advantage of it.

"Pretty much everyone has talked about it and is in the process of rolling it out or going to do so shortly," meaning by 2014, analyst Chetan Sharma, of Chetan Sharma Consulting, said via email.

Earlier this year, SK Telecom in South Korea claimed it had the first publicly available LTE-Advanced network with carrier aggregation. The carrier is combining two 10MHz bands and says that gives a theoretical top speed of 150Mbps.


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