How to optimise a wireless device for 5G performance

5G promises higher speeds, lower latency and increased bandwidth. The technology is already powering a wave of new applications when paired with compatible mobile devices.

But just building the 5G network is not enough. Wireless devices must be upgraded and optimised for them to work at full capacity – and satisfy the customer.

4G LTE to 5G – are new 5G-optimised devices needed?

The full benefits of 5G can’t be achieved without the proper hardware. Although some frequencies are shared, 5G transmits across broader and different frequencies to 4G.

5G operates across three different bands:

  • Low band, which ranges from 600 MHz to 3GHz
  • Mid band, from 3GHz to 6GHz
  • Millimetre wave range, known as mmWave, on wavelengths greater than 10GHz

4G operates on frequencies between 617GHz and 2.5GHz, at the lower end of 5G bands. Existing device technology supports mainly low and mid band 5G, with 5G mmWave device development catching up. In terms of channel bandwidth, 4G works on up to 20MHz. Internet of Things (IoT) devices are typically limited to 200kHz, while 5G promises up to 400MHz. In theory, this allows interconnectivity of many devices, estimated to be up to a million per square kilometre.

With all the network technology changes, to really benefit from 5G, many mobile devices must be optimised to incorporate:

  • Antennas that can operate across new frequencies
  • New batteries to cope with higher power drain
  • Improved thermal management
  • Printed Circuit Board (PCB) design reconfiguration, required to accommodate new antennas, batteries and thermal management

Not all mobile devices will need updates, as 4G and 5G share some frequencies. Before investing in new product development, device designers should check the needs of the target mobile application first.

Optimising antennas to accommodate new frequencies

Antennas are designed to perform best across a predefined set of frequency bands. 5G’s frequencies and bandwidth allow for higher speeds of data transfer and low latency. It is important to choose the right antenna so that mobile devices can support these frequencies.

The frequency also means the antennas typically occupy more space. This is because the frequency bands that are accessible to an antenna are influenced by the length of the ground plane. A minimum of a quarter wave ground plane is required. So lower frequency bands using SMD antennas will need a longer ground plane, which has implications for PCB design and device size.

Device designers should note that 4G and 5G radio signals are not received or transmitted in quite the same way. 5G works both as a standalone (SA) and non-standalone (NSA) cellular network. NSA 5G networks continue to use the 4G core infrastructure. As the name suggests, SA 5G connects directly to 5G infrastructure. For low and mid band, the existing 4G infrastructure is used and will not be decommissioned. This suggests that for applications that don’t need advanced 5G capabilities, 4G works just as well.

Optimising power supply for 5G use

A fully-optimised mobile device battery underpins user experience and performance. With mmWave still in the early stages of roll-out, 5G coverage is patchy and often non-contiguous. As a result, devices skip between 5G and 4G. This uses extra power and drains battery life faster. As the 5G roll-out continues, some coverage issues will be resolved. But this will likely remain a design challenge across mobile devices for many years.

Depending on the application, 5G mobile devices have multiple antennas to operate across a wider range of frequencies. As a result, they may be connected to multiple networks at the same time. This drains power faster than connection to a 4G network. For the device to operate over longer timescales, its battery will require optimisation.

New thermal management required for 5G

Extra thermal management measures are needed for 5G mobile devices. This is because each device requires multiple antennas to receive signals from 5G mmWave towers. The technology is called multiple input-multiple output (MiMo). As it consumes more power, the PCB heats up.

Optimising PCB design for 5G and the impact on device size

The high frequencies needed for 5G mmWave create issues with signal reflections, which can cause ringing. To tackle this, the PCB must implement correctly terminated signal lines and impedance matching.

The increased ground plane and spacing required for 5G SMD antennas means PCBs, and potentially the resulting mobile devices, must be larger. Or use a solution such as a flexible printed circuit antenna (FPC). Larger batteries and increased thermal management will also impact PCB design and size.

Choosing antennas for 5G, 4G LTE or both

With the emergence of 5G and its benefits, and the continued use of 4G frequencies with its advantages for some applications, device designers have multiple challenges when optimising a mobile device for 5G. We recommend that antenna selection forms part of the early design stages of your device as this will ensure optimal performance and compliance with network carrier requirements.

To see our full range of antennas for cellular devices – including 5G and 4G – browse our antennas or download our antenna comparison guide.

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