SingTel claims to have taken a step closer to the launch of 5G with the introduction of a 450Mbit/s service based on more advanced 4G technology.

The Singaporean incumbent said in a statement that its new LTE-Advanced (LTE-A) service is available "nationwide" and 50% faster than older 4G networks.

Singapore Telecommunications Ltd. (SingTel) (OTC: SGTJY) appears to have made investments in a technology called 256 QAM (for quadrature amplitude modulation) across its 4G footprint to provide the higher-speed services. Described as a "pre-5G" technology, 256 QAM essentially boosts spectral efficiency so that networks can carry up to a third more data.

The move is a sign of the early progress that some operators are making as they upgrade 4G networks in advance of a 5G rollout several years from now. (See 4.5G Sets High Bar for 5G.)

Besides switching on the LTE-A service, SingTel also said it had tested a 1Gbit/s service on a live network in collaboration with Swedish vendor Ericsson AB (Nasdaq: ERIC). Carried out at pilot sites in the region of Pasir Ris, those 1Gbit/s trials used 256 QAM along with 4x4 MIMO (for multiple input, multiple out) and carrier aggregation technologies.

The 4x4 MIMO system doubled the number of data paths running between basestations and devices, while carrier aggregation combines spectrum channels -- sometimes from different frequency bands -- to increase bandwidth.

SingTel's plan is to start rolling out 4x4 MIMO on its commercial network from next year so that it can provide 1Gbit/s services in what it calls "high-traffic locations." It expects devices that can support the technology to start appearing at the end of this year.

At the moment, only customers with Samsung Galaxy S7 devices will be able to make use of the 450Mbit/s service, but a "soon-to-be-released" software update will in due course make the higher speeds available to LG V20 users, according to SingTel.

Some other compatible smartphones are set for launch early this year, says the operator.

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Momentum is now building for LTE-A and LTE-A Pro technologies, which operators besides SingTel increasingly see as an important step on the journey to 5G.

While much of the noise about "4.5G" is emanating from the US market, Russia's Mobile TeleSystems OJSC (MTS) (NYSE: MBT) flagged an LTE-A Pro upgrade in December. European operators including Deutsche Telekom AG (NYSE: DT), Orange (NYSE: FTE) and Vodafone Group plc (NYSE: VOD) are also eyeing 4.5G capabilities, Light Reading has learned.

"With LTE-A Pro, we are already testing technologies and characteristics that will contribute to 5G," said a spokesperson for Deutsche Telekom. "Our major activities in 2017 will be the strategy, testing and implementation of enhancements coming through the 3GPP Release 13 and 14 standards."

Last year's Release 13 covered many of the technologies that operators are now testing or rolling out under the 4.5G label, while a forthcoming Release 14 -- the last pre-5G update -- seems likely to cover some of the features that Finnish vendor Nokia Corp. (NYSE: NOK) is already marketing as 4.9G technology.

Speaking at a press briefing in December, Sami Elhage, the head of Nokia's mobile networks business, said the vendor had then signed 110 contracts for the rollout of 4.5G networks and would introduce 4.9G technology later this year. (See Nokia Boasts 4.5G Momentum With 110 Deals.)

The 3GPP's Release 15 will incorporate the "Phase 1" 5G specification, with commercial 5G networks likely to start appearing from 2020 onwards. (See 5G on Track but Fragmentation Still a Concern.)

Business advisory firm Deloitte reckons more than 200 carriers will be offering LTE-A services across their networks by the end of this year, with 20 operating LTE-A Pro capabilities.

"The technology building blocks for 5G readiness are being deployed in 2017, and in some markets are already in place," said Dan Adams, the lead UK partner for telecom at Deloitte, in a statement.

— Iain Morris, , News Editor, Light Reading