As mobile operators across the world are faced with the challenge of supporting radically increased throughput, largely the result of big video traffic, across their networks, they are looking for technological answers that allow them to deliver 5G-like experiences over today’s 4.5G networks. Live mobile video is projected to grow 39-fold between 2016 and 2021 and mobile video will account for 78% of all mobile traffic by 2021, according to Cisco’s 11th Mobile Visual Networking Index. The potential speed and coverage capabilities of 5G mobile will alleviate operators’ pressures but 5G itself remains some years away with early testing and standardisation efforts only starting to gather pace. What’s needed is a way to address network demands with mature technology today.

The good news is that 5G has always been thought of as an onward evolution from 4G and many of the technologies that have been developed to extend the capabilities of 4G, such as LTE Advanced, LTE Advanced Pro and others that make up the 4.5G family of solutions, are also applicable to 5G. Neville Ray, the chief technology officer of T-Mobile USA, welcomes this upgrade path. “T-Mobile does have its own 5G trials running, but it’s in 4G that carriers and equipment makers will develop many of the technologies they’ll need for 5G,” he has said. “That includes 4×4 MIMO, a multi-antenna technology to boost network performance, which T-Mobile started using last year. More advanced MIMO is expected to play a role in 5G.”

Industry colleagues agree. “If you keep in mind the latest developments regarding 4G and the pure evolution of technology, it’s not easy to identify where 4G will end and where the next generation will start,” Bruno Jacobfeuerborn, the chief technology officer of Deutsche Telekom, has pointed out. “LTE Advanced isn’t the last stop on the road to 5G. The successor, LTE Advanced Pro, looks very promising in our trials. 4G will be adopted as a part of generic 5G – as a cornerstone of its capability, serving the significant mobile broadband, mainly people-focused, needs. There is a lot of technology still to come in 4G. These technologies will play out in the next four years.”

Into the gigabit era
The effort is now moving from conceptual discussions and limited trials into mainstream commercial deployments. A key enabler is the availability of devices that can support the gigabit throughputs needed and these are now coming to market. At Mobile World Congress 2017 there were exciting developments with the launch of new gigabit smartphones from vendors like Sony. Chipset vendor Qualcomm demonstrated gigabit per second throughput at the event on devices that support 4×4 MIMO (multiple input, multiple output) . This capability represents a significant step towards 5G because the individual user experience delivered over 5G networks will be beyond gigabit per second throughput and the new Sony device has the ability to provide a 5G-like experience over 4.5G networks.

The technology that underpins this capability is 4T4R (4 Transmit 4 Receive), which effectively doubles the number of base station antennas that are currently being used in LTE networks. 4T4R will be the basic configuration for a network that supports gigabit connections.

4T4R is already a market reality
True Move H, a nationwide mobile operator in Thailand, has already deployed 4T4R 4×2 MIMO at more than 6,300 sites nationally in the world’s largest 4T4R network to date. Since launch in mid-2016, the operator has seen average cell throughput increase by 20% and cell edge throughput increase by 40%. Significantly, following the announcement of its launch of the world’s first 4T4R network on 4 July 2016, the operator’s stock price increased by 20% in the following week.

In South Africa, operator MTN has rolled-out 4T4R across all its new sites because 4×4 MIMO smartphones are coming to market. The operator had Qualcomm assess its needs and the vendor suggested rolling out 4×4 MIMO to improve coverage and capacity and advocated maximising 4×4 MIMO device penetration to realize the gains. Expected gains from 4×4 MIMO versus 2×2 MIMO are a 74% increase in downlink throughput and a 39.5% increase in uplink throughput.

A default configuration for 5G
For operators, 4T4R is mature and has applications in 4.5G networks today and this means it can become the default configuration for 5G. Operators’ technical leaders clearly understand the value of 4T4R, which offers downlink capacity across four streams that is 1.2-1.8 times more spectrally efficient that 2×2 MIMO. In addition, the technology offers uplink coverage that is 25% greater than uplink utilizing 1×2 MIMO.

The maturity of the 4×4 MIMO ecosystem with devices, customer premise equipment (CPE) and chipsets all commercialised and globally available means 4T4R has the ability to enable operators to benchmark a 5G-like network in a 4.5G environment. With more than 30 4T4R networks delivered in 2016 in more than 20 countries the technology is well-established and more than 100 4T4R networks are expected to be live by the end of 2017.
In addition, 4T4R is the first technology to introduce effective beamforming which is a critical function for 5G networks. Preceding technology 2T2R, which can only support two channels, can’t support beamforming. In contrast, 4T4R has four channels so it can support up to 16 wide beams with the help of PMI (Precoding Matrix Indicator) feedback. This, when added to the latest terminals which support TM9 advanced functionality for massive MIMO, provides a far better experience for users.

4T4R has therefore become the default configuration for 5G and now is the time for operators to invest in the technology so they can maximise the advantages to in terms of capacity and coverage in their 4.5G networks and provide their users with 5G-like experiences while still in the 4.5G era.


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