Clearwire, China Mobile Detail Coming TD-LTE Testbeds

Clearwire will test its LTE network in two U.S. cities and China Mobile will build test networks in select Chinese cities early this year to foster development of a global ecosystem for the version of the technology they will be using.

Clearwire will set up a test network in a section of Herndon, Virginia, and one in an area in Phoenix, and one of China Mobile's systems will be in Beijing, the companies announced on Tuesday. They will be available to mobile device developers early this year, the companies said. By making these networks available to device manufacturers, the two carriers hope to encourage hardware development on TD-LTE (Time-Division Long-Term Evolution), the system that both operators will use for their entire infrastructures.

Along with a group of carriers called the Global TD-LTE Initiative (GTI), Clearwire and China Mobile have agreed on common test specifications for TD-LTE devices anywhere in the world, they announced Tuesday. The two carriers and other TD-LTE operators will set up labs in different parts of the world that use the same test platform and interoperability test environment.

The goal is to encourage companies to build smartphones, tablets and other mobile devices for TD-LTE, a form of the technology designed for carriers that have a different spectrum configuration from the major operators that have rolled out LTE so far, such as Verizon Wireless. TD-LTE, also known as LTE TDD (time-division duplexing), is designed for networks where both upstream and downstream transmissions occur in the same block of spectrum. Though a majority of the world's carriers that have announced 4G plans have committed to using LTE, most will be using the FDD (frequency-division duplexing) form of it, which uses different blocks of spectrum for upstream and downstream traffic.

Though mobile devices can be made compatible with both types of LTE, and manufacturers will be able to test such devices on these test networks, the focus of the upcoming trials will be on dedicated TD-LTE devices. In order to foster competition and high-volume, low-cost manufacturing of TD-LTE products, the technology's proponents intend to kick-start vendors' development of the gear.

The testing will focus on frequencies between 2.3GHz and 2.7GHz, the band where Clearwire holds its strong spectrum holdings in many areas across the U.S. The two carriers see these frequencies as the main band for TD-LTE in many parts of the world.

The announcement on Tuesday fleshed out details of a deal that Clearwire and China Mobile disclosed in September. Since that time, Clearwire has secured funding and network-sharing deals with Sprint Nextel, its majority owner, that brought it closer to its goal of building the LTE network.

Clearwire operates the WiMax network used by Sprint, while also selling services of its own on that system. When it comes to LTE, Clearwire and Sprint each will be deploying networks, with Sprint using the FDD version and Clearwire using TD-LTE. Sprint plans to use capacity from Clearwire and offer dual-mode devices to take advantage of both networks. Sprint also plans to keep offering service over Clearwire's WiMax network for the next few years.

Stephen Lawson covers mobile, storage and networking technologies for The IDG News Service. Follow Stephen on Twitter at @sdlawsonmedia. Stephen's e-mail address is stephen_lawson@idg.com

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