Qualcomm, Ericsson, SingTel hit 260Mbps in live FDD/TDD demo

Ericsson, Qualcomm, and Singtel have demonstrated the first carrier aggregation of FDD and TDD to achieve speeds of up to 260Mbps, meaning networks have more choice over which 4G standards to employ, as several can be used at the same time.

Standards are great, everyone should have one. And 4G has loads, so it’s sometimes tough to get things to work together, even within the same standard.

One of the (many) clever things about 3G LTE, also known as 4G, is that you can have carrier aggregation — the bandwidth can be combined at different parts of the radio spectrum to achieve more throughput. This allows governments to sell (and MNOs to buy) non-contiguous spectrum and the system to still run at a decent lick.

There are 39 different sets of frequency bands, running from around 452MHz right up to 3.8GHz. Some use TDD (Time Division Duplexing) and some use FDD (Frequency Division Duplexing), and at some frequencies both can be used.

Duplexing separates the transmission from the reception, and while technology has been shown which can do both at the same time, it’s still at the trial stage.

What’s special about Tuesday's announcement is that it combines the two kinds of duplex to carry out the carrier aggregation. Combining two bands with the same duplex method is well understood (and there are commercial services running with speeds higher than those quoted here for the mixed duplex aggregation) but the ability to do it is still both clever and useful.

Qualcomm, Ericsson and SingTel claim network optimisation

FDD/TDD carrier aggregation enables operators to supplement their FDD networks with a cost-efficient deployment of TDD. For operators using TDD bands, the TDD uplink coverage can be a constraint.

By combining TDD and FDD spectrum, low-band FDD can deliver good uplink coverage while the TDD band can be leveraged for higher downlink capacity. LTE FDD/TDD aggregation enables spectrum from both LTE FDD and LTE TDD to be combined to deliver higher peak data speeds and improve app coverage across the network.

Ericsson claims the technology will lift network performance, giving early adopter mobile operators a competitive advantage, with an improved app coverage for mobile device users across the network. It increases TDD coverage area by 70 per cent and TDD downlink speeds compared with one LTE carrier, as well as optimising spectrum.

"We are glad that Ericsson is delivering innovations that keep us at the front of such technology development," said Tay Yeow Lian, Singtel's managing director of networks.

"We are already using dual-layers of LTE FDD with LTE-advanced carrier aggregation, and will continue to explore the option of bundling TDD spectrum into the LTE carrier aggregation to expand network capacity," he added.

"We demonstrated that the combination of low-to-mid band FDD with high-band TDD can provide significant network performance gains," said Per Narvinger, head of product area LTE, Ericsson. "This complements the FDD/TDD interoperability work which we have already commercialized in countries where TDD spectrum is granted."

The technical demonstration took place at the Singtel office in Singapore on 3 October, using a Qualcomm Snapdragon 810 processor, and Ericsson high-performance LTE software, designed to support the company's multi-standard RBS6000 family of base stations.

In the demonstration, Ericsson aggregated 20MHz of LTE FDD spectrum with 20MHz of LTE TDD spectrum, supporting peak data rates up to 260Mbps. Ericsson expects this to be out of the lab and in a commercial product next month.

However, the downside of all this is that networks can no longer claim that some bits of spectrum are worthless, and the governments can go back to extorting the telcos' licences. ®