GSMA: Dual-Mode a Must for LTE Devices

HONG KONG -- For Long Term Evolution (LTE) to succeed, it's "absolutely critical" that devices be able to support both the TDD and FDD versions of the next-generation mobile technology, according to GSM Association (GSMA) Director General Anne Bouverot.

Bouverot told a conference held by the Global TD-LTE Initiative (GTI), an industry group promoting Long Term Evolution Time Division Duplex (LTE TDD), that it was not enough just to get the products to market. (See Global TDD Initiative Launched at MWC 2011.)

"That won't drive the market to scale. The key requirement for success is dual-mode chipsets for TDD and FDD LTE," she told a packed lecture hall here in Hong Kong on Tuesday, a day ahead of GSMA's Mobile Asia Congress event.

"I cannot emphasise enough that dual chipsets are absolutely critical for the success of this industry. We can't allow the industry to split again between technologies as we saw in the past," stated Bouverot, citing GSM and CDMA in the 2G era and the trio of 3G technology standards -- WCDMA, CDMA2000 and TD-SCDMA.

The good news is that, unlike with TD-SCDMA (China's home-grown TD-based 3G technology), the LTE TDD standard is backed by virtually the entire chip sector.

The chipsets are the key. Only four chip vendors -- mostly startups -- designed and built TD-SCDMA chips, points out Bill Huang, general manager of China Mobile Ltd. (NYSE: CHL)'s Research Institute.

Now, though, around 16 chip specialists, including Qualcomm Inc. (Nasdaq: QCOM), ST-Ericsson and Sequans Communications , are doing "various kind of baseband" for LTE TDD, Huang stated. (See Sequans Unveils New LTE Chips.)

To date around 35 LTE TDD terminals (mostly data cards or MyFi-style hotspots) have been developed, while ZTE Corp. (Shenzhen: 000063; Hong Kong: 0763) has already produced a dual-mode card.

But Huang said the problem is not whether the two 3GPP standards will be combined into one chipset, but whether the chips can support all the required spectrum bands. "The question is: What spectrum from TDD or what spectrum from FDD that [the chip] will support?" stated the China Mobile man. "We now have six spectrum bands identified that will cover maybe 80 percent of the world -- we may increase that to eight bands to get 100 percent coverage."

There are other considerations too: Current LTE TDD devices are voracious consumers of battery life, using 30-40 percent more power than a W-CDMA device for similar performance, Huang acknowledges. And as well as spectrum bands, new devices will also have to support a plethora of different radios.

Operators are pressing ahead with their plans, though. For example, when SoftBank Mobile Corp. formally launches its full LTE TDD service under the Softbank 4G brand in February or March 2012, the early devices will carry chips that support both types of LTE, HSPA+ and GSM. (See Softbank Preps Pseudo-LTE TDD Service.)

— Robert Clark, freelance editor, special to Light Reading

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