At least half a million base stations will be installed or upgraded for the TD-LTE standard by the end of 2016, according to a new study by ABI Research.

TD-LTE is the Time-Division Duplex (TDD) variant of the fourth-generation (4G) Long Term Evolution (LTE) wireless standard. Although LTE is only just gaining a foothold in some parts of the world, a number of operators are already experimenting with TD-LTE, which runs on a cheaper part of the spectrum than LTE and has much less traffic.

Unlike LTE, which carries two separate signals – one for uploading and one for downloading – TD-LTE uses a single channel, and dynamically assigns bandwidth to each connection based on user requirements. However, the two standards are similar enough that a single chip can access both.

China Mobile, which developed TD-LTE in 2007, is now pushing to gain better international recognition for the technology. The company started its second phase of the TD-LTE Large Scale Trial Initiative (LSTI) in December, and plans to install an additional 10,000 to 20,000 TD-LTE base stations in 2012, followed by a further 60,000 in 2013.

Meanwhile, TD-LTE commercial services have been launched in Brazil, Japan, Poland, Saudi Arabia, and other countries. TD-LTE deployments are also underway in Australia and Scandinavia and large-scale TD-LTE networks are planned in the United States and India.

TD-LTE is deployed in the 2.6 GHz band of spectrum, currently used for WiMAX. According to ABI Research, many WiMAX operators with unpaired TDD frequency spectrum are now looking to upgrade to TD-LTE rather than WiMAX 2 – which was developed to provide higher data rates and increased capacity.

“A funny thing happened on the way to the forum,” said Jim Eller, principal analyst of wireless infrastructure for ABI. “Despite starting two years later than WiMAX 2, TD-LTE emerged as a viable alternative.”