What does 5G mean for legacy cellular technology?

Around the world, data demands are at unprecedented levels. The COVID-19 pandemic has ‘locked down’ large parts of the world. Wireless communications are enabling economies to keep going, keeping people entertained, and accelerating the adoption of new technologies, such as telemedicine.

The Long-Term Evolution (LTE) project has played a significant role in putting the world in this position. Businesses, governments, medical institutions and consumers have access to broadband-standard data through cellular networks.

5G naturally comes into context. Although conspiracies linking the technology to the pandemic have perpetuated throughout social media (without evidence), the next generation of wireless tech could support this transition.

At the time of writing, data demands are at never before seen levels. Due to the COVID-19 pandemic, countries are in a state of ‘lockdown’, with economies on the slowdown and media consumption peaking. The state of wireless technologies and infrastructure could be about to change forever.

Changes to LTE: the immediate plan

The installation of 5G infrastructure has slowed over the last two months, understandably so. Even so, the availability of the new radio is not going to happen over night. There are still only a handful of devices that support the technology, creating a chicken and egg scenario; devices won’t launch supporting the tech until it’s widely available, but the infrastructure is costly, so investing over a longer period of time is the most sensible option for cellular networks.

Over the last two years, cell carriers have instead looked to double down on LTE. And, as the industry has a tendency to do, a number of new marketing terms now refer to roughly the same thing. XLTE, LTE Plus, LTE Advanced, 5G Evolution, Extended-Range LTE – while different, carriers are using these terms to describe the moves they are making to enhance LTE performance. Verizon, for example, purchased part of the AWS spectrum to boost LTE bandwidth, while also acquiring parts of the millimeter wave required for the 5G new radio.

Switching off legacy networks?

In the UK, new cellular technologies such as Narrowband-IoT will be bundled into the fifth-generation technology. But for legacy cellular networks, the infrastructure change means it’s time to be sunsetted. In some cases, they are even being switched off. Three 2G networks are planned to be switched off in Britain, which has caused controversy, as these technologies are still used for ‘senior’ phones, telematics and some smart metering devices. 3G networks are planned for sunsetting, too – but some commentators suggest that the 2G switch off will have a greater impact on consumers and business. It’s safe to conclude that it’s probably worth examining alternative technologies for devices penned for 2G and 3G use.

The state of 5G infrastructure

In the UK, early investments have been made by mobile virtual network operators (MVNO) such as Vodafone and Telefonica UK. This joint venture represents one of London’s biggest investments into wireless infrastructure. This alliance of MVNOs is one of many firsts. As the footprint for 5G continues to expand across the UK, MVNOs such as EE, O2, Vodafone and 3 are all trying to race to the finish line with the greatest number of cities connected.

In the USA, the Tech Editor for CNN Sam Kelly reports: “The next generation of ultra-fast wireless, continues to expand in the US. The catch, of course, is you'll need to be in the right city with the right device to access it.

"The current state of 5G in the US [is] inconsistent, [promising] lightning-fast speeds, downloading two-hour movies in seconds, but often struggled to connect indoors and when blocked by environmental factors, such as nearby trees.”

Higher data loads mean learning new antenna technologies

What’s clear is that the potential of LTE+ technology is huge and 5G infrastructure replacing 4G infrastructure can carry much more data at higher speeds. But to manage risk, network operators responsible for infrastructure can upgrade existing 4G networks by using new MIMO (multiple input multiple output) antenna arrays and MU-MINO beamforming techniques.

On MIMO, McKinsey highlighted in 2018 that: “This will be the natural path for most operators, allowing them to minimise investments while the incremental revenue potential of 5G remains uncertain. When network upgrades are no longer sufficient to support the increased traffic, operators will need to build new macro sites or small cells. That point in time will vary by location, but simulations show that most operators will need to embark on significant new build-out between 2020 and 2025.”

To understand how these will change infrastructure requirements, the same McKinsey study looked at three specific categories: enhanced mobile broadband, IoT and mission-critical applications:

“These use cases will require network performance to increase 10-fold over current levels across all network parameters, as measured by latency, throughput, reliability, and scale. To get there, mobile operators must invest in all network domains, including spectrum, radio access network (RAN) infrastructure, transmission, and core networks.”

New 5G infrastructure brings technical challenges

Device designers need to understand how the new infrastructure will be built so they can design the correct antennas into their products. A key element of that infrastructure is the spectrum used. Changing frequencies from 4G to 5G fundamentally impacts antenna choice.

Transmission of 5G is dependent on the reliability and robustness of the spectrum. There will be dozens of new frequencies bought by network operators. In addition, the mmWave band, which is between microwave and infrared, is being used for high-speed wireless communications.

As well as being expensive for operators to licence, mmWave signals face physical challenges, finding it harder to pass through buildings and trees, and are impacted by weather. However, it also has huge advantages such as using a software fix to allow both 5G and 4G to operate on the same band.

Conclusion

As 5G is already operating and its growth is likely to be significant, product designers must understand how it impacts on their embedded antenna choice when creating new devices. There are steep technical challenges related to the change in frequency, the resulting impact on antenna size and configuration and the architecture of device PCBs.

Designers who incorporate the right approach from the outset of the design process should have no problems transitioning their device designs along the LTE path from 4G/LTE to 5G.

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