Now that Sprint Nextel Corp.'s mergers with Clearwire LLC and Softbank Corp. are complete, the carrier's Network Vision could soon take on a fresh 4G flavor with LTE TDD.

Sprint bought the rest of Clearwire that it didn't already own primarily to get its hands on its valuable spectrum holdings. Those holdings were in 2.6GHz bands used for WiMax now but suitable for deploying Long Term Evolution Time Division Duplex (LTE TDD). This is a technology -- also known as TD-LTE -- that no other operator in the U.S. uses, but one that is accelerating rapidly across the globe. (See Defining 4G: What the Heck is LTE TDD?)

Sprint hasn't said when it will deploy the next-generation network, but Ovum analyst Daryl Schoolar says it could be as soon as the fourth quarter of this year.

If so, this will be positive news for its vendor partners, Alcatel-Lucent, Ericsson AB and Samsung Corp.. Both Ericsson and Alcatel-Lucent have experience with the burgeoning tech through its biggest proponent, China Mobile Ltd., and Samsung was an established Clearwire base station vendor. There's little chance Sprint will look elsewhere to build out LTE TDD.

"I would think with Sprint trying to consolidate everything, it would most likely want to have the same FDD LTE and TDD LTE vendors in the market," Schoolar says. "They'll want to follow the path and keep the same vendors in the same regions."

For Alcatel-Lucent, especially, it may be a game of catch-up for a while. Its LTE TDD footprint pales in comparison to Samsung and Ericsson. Schoolar notes it is difficult to determine whether Alcatel-Lucent is behind on the technology itself or if it just hasn't pursued the market as aggressively given its recent corporate restructuring. For its part, an Alcatel-Lucent spokesman says the vendor has several LTE TDD trials and customers.

Even if Sprint does move to LTE TDD in the fourth quarter, the wait on devices for the network will be a longer -- at least until next year. The Global Mobile Suppliers Association (GSA) says there are already more than 200 LTE TDD devices on the market, but Sprint's network will no doubt precede their entry into the U.S.

— Sarah Reedy, Senior Editor, Light Reading