Interest in TD-LTE, the version of LTE slated to run in the unpaired spectrum known as Time Division Duplex, has heated up rapidly--so much so that TD-LTE deployments won't trail far behind FDD (Frequency Division Duplex) deployments, said Dan Warren, GSMA's director of technology, in an interview with FierceBroadbandWireless.
To wit: Ericsson announced a deal last week with Chinese vendor Datang in a bid to gain significant experience with TDD solutions. As part of the deal, Ericsson will begin integrating Datang's TD-SCDMA radio access network equipment into its own 3G offering. TD-SCDMA is China's homegrown 3G standard that China Mobile and others are using, and TD-LTE is seen as the next generation. Today, Nokia Siemens Networks announced a successful TD-LTE data call with Samsung. And of course, there's the biggie: The WiMAX Forum's announcement to speed up timelines for releasing faster versions of WiMAX thanks to the threat of TD-LTE encroaching on its turf.
"TDD is going to be a much more important part of the ecosystem from a 3GPP perspective than ever before," Warren said. "With TD-SCDMA networks up and running in China, vendors are gaining more confidence in the technology."
It used to be that China Mobile was driving all of the momentum behind TD-LTE, Warren said. China Mobile aims to be the first to deploy such a network. But with Qualcomm aiming to deploy TD-LTE in the 2.3 GHz band in India--if it wins a license--TD-LTE will have the world's two fastest growing markets, China and India, driving the momentum. Moreover, mobile operators in Europe are sitting on a bunch of vacant TDD spectrum that was attached to their 3G licenses and more TDD spectrum is expected to be released in auctions across the globe.
"The more you get down the curve of exponential increases in data traffic, the more people will need to use every scrap of spectrum available," Warren said. "As we move forward people will more and more focus on spectrum rather than just paired or unpaired, and networks that can utilize both."
Warren expects TD-LTE technology to be deployed almost in parallel with FDD LTE deployments. He expects deployments to go something like this: 10 FDD LTE networks rolled out by the end of 2010, 50 FDD networks by 2011 with a focus on ramping up subscriber growth and deploying voice over LTE with TD-LTE networks being launched in mass the same year and scaling in parallel with FDD networks. In 2012, there will be mass uptake of both LTE versions, he said.
Analysts have pontificated about the possibility of WiMAX operators flipping to TD-LTE since WiMAX operates in the TDD spectrum. The theory is that as WiMAX operators consider their next-generation WiMAX option, 802.11m, they might as well flip to TD-LTE since about 80 percent of the infrastructure is similar. Clearwire has indicated it could very well deploy TD-LTE in the future and has asked the 3GPP, along with vendors, to develop specs that would enable TD-LTE's entrance into the 2.6 GHz band.
But Warren said such a transition is not an easy one. "It has got to be something that is done as a business decision to retask TDD spectrum, and that becomes tough because you run the risk of potentially running two technologies," he said. "It's technically challenging to retask spectrum. Both technologies may be OFDMA, but there are different frame structures and different ways to carve up the spectrum... They may look really familiar but there are fundamental differences."--Lynnette