Dual FDD-TDD LTE networks on the horizon: Aeroflex adds first test support

Want to know where the industry's headed? Always worth checking what the test vendors are up to. Test company Aeroflex will be demonstrating an LTE TDD-FDD handover test at Mobile World Congress, a capability it announced just in January 2013.

TDD-FDD handover for dual-standard networks is not something that would have been high up the list too long ago, but spectrum utilisation is becoming increasingly important, and operators are less willing to leave TDD spectrum on the bench.

Aeroflex stated in its press release that, “Network operators around the world are already commissioning dual standard networks as part of the rapid expansion in TD-LTE (LTE TDD) networks.” Indeed, just today came the news Vodafone has bid for and acquired TDD spectrum in the UK, although it is probably not yet the best example of an operator with a TDD-FDD consumer strategy.

China Mobile Ltd (Hong Kong) launched the first commercial FDD-TDD dual mode network in December 2012, using equipment from Ericsson, and Aeroflex claims that an increasing number of operators rolling out LTE in both paired and unpaired spectrum. In September 2012, SK Telecom again with Ericsson, and Altair Semiconductor, said it had developed a two-way handover technology that supported both Duplex modes in one device, and had successfully demonstrated the technology in a moving vehicle environment for the first time in the world.

“Dual-standard TDD/FDD LTE networks are likely to grow in importance towards the end of this decade, as operators start running out of spectrum,” said Caroline Gabriel, Research Director at Maravedis Rethink. “They will need to make the best use of this scarce resource, and this will include utilising bands of unpaired spectrum. Even networks that are currently FDD only may begin to use TDD for offloading.”

According to ARCchart there are already more than 50 mobile operators worldwide committed to TDD technology for LTE. The GSA suggests that there were 13 commercial LTE networks launched as of January 2013. Most of the TD-LTE compatible mobile devices launched commercially to date support both FDD and TDD modes of operation.

If there are going to be more such networks, then handover’s going to be key. “Verifying end-user performance when calls are handed over between FDD and TDD networks is crucial for operators to deliver a good customer experience,” said Nick Carter, Senior Product Manager at Aeroflex.

That may leave Anritsu feeling a little smug – the Japanese test company had a working UE carrier aggregation test demo at last year’s event.

LTE-A Features
Aeroflex company will also be demonstrating carrier aggregation test functionality for the first time at MWC, using its TM500 Test Mobile to emulate the UE under test, along with the 7100 Digital Radio Test Set to perform the measurements. As well as carrier aggregation, the TM500 supports all the key LTE-A features of 3GPP Release 10 including enhanced Inter Cell Interference Cancellation (eICIC) and 3GPP Release 10 Transmission Mode 9 (TM9).

That may leave Anritsu feeling a little smug – the Japanese test company had a working UE carrier aggregation test demo at last year’s event.