By Norman Quesnel, Senior Member of Marketing Staff
Advanced Thermal Solutions, Inc. (ATS)
Qpedia 107, Featured Article
Next-gen and brand new technologies are quickly developing and already impacting life around the globe. These include artificial intelligence, the Internet of Things, autonomous vehicles, virtual reality, and smart buildings and cities.
Another advanced technology essential to all these technologies is 5G communications.
5G is the 5th generation of mobile networks, a significant evolution of today’s 4G LTE networks. 5G is being designed to meet the exploding growth in data and connectivity needs of today’s modern, highly populated society. It brings three major advances. First, it provides bigger channels to speed up data downloads and uploads. It also reduces latency which improves response times. And it connects many more devices at one time once, allowing more sensors and smart devices. 
5G electronics hardware ranges from base stations to transceivers to handsets. And transitioning these to 5G has some drawbacks and limitations. Many are due to 5G’s faster, smaller wave transmissions. 5G frequencies are found in low-band, mid-band, and high-band ranges, which can be matched to various conditions and applications. Much of the 5G spectrum is in extremely high frequency (EHF) or millimeter wave (mmWave) frequencies.
Faster millimeter wave frequencies are more susceptible to the environment. They have difficulty passing through walls and windows, so indoor coverage is limited. And millimeter wave communications can be susceptible to rain, fog and other atmospheric interference. They also need shorter distances between the devices sharing them. As a result, millimeter wave networks require more cells and base stations, particularly in densely-populated areas with millions of connections. 
Because each spectrum band has different radio properties, infrastructure hardware, such as towers and antennas vary accordingly. In the low band spectrum, the infrastructure and placement are relatively similar to current 4G deployments. In 5G’s mmWave range, towers are shorter, discrete, and more densely placed. Their antennas are designed for short distances and use techniques like beam-forming to overcome propagation shortfalls. Some antennas are designed to support new 5G-related technologies like massive MIMO that produce greater capacity out of the same spectrum. 
And, as with most high power electronic devices, thermal issues could also adversely impact performance. Much of the outdoor electronics in 5G network architecture must deal with heat (and cold) extremes, not only environmental but from their own high power, condensed packages and structures. And, some 5G handsets have shown susceptibility to higher ambient temperatures.
Fortunately, in most cases, thermal management techniques are already available to solve heat issues facing 5G communications devices.
Base Stations and Cells
Base stations, macro cells, micro cells, small cells and other devices are all part of the dynamic cell phone infrastructure. Macro cells that cover a wide area, micro cells are used for densification of coverage in highly populated areas, and pico cells boost coverage within buildings These will need upgrading or replacing to accommodate 5G. And many more will be needed to pass along shorter reach mmWave signals. 
Relatively short-range mm wave frequencies need some kind of low-power antenna every 1,500 feet or so. This is a higher saturation than with macro cell sites now at work in many suburbs. The small, individual millimeter-wave cells are much less powerful than larger cell sites, but the high frequencies drop off so quickly with distance that you need more of them.
One of the major base station OEMs is Nokia. Their models typically include one or more cooling methods, depending on their application and location. The liquid-cooled Massive MIMO base station (below) is a third lighter and half the thickness of its predecessor. The smaller scale lets it better blend in with walls and buildings. By adding liquid cooling Nokia was able to remove internal cooling fins which had taken up a lot of space. 
A typical 5G base station can consume twice or more the power of a 4G base station, and energy costs can grow even more at higher frequencies, due to a need for more antennas and a denser layer of small cells.
5G macro base stations may require several new, continuously running, power-hungry components, including microwave or millimeter wave transceivers, field-programmable gate arrays (FPGAs), faster data converters, high-power/low-noise amplifiers and integrated MIMO antennas. 
5G requires multiple, multi-element antennas. Current strategies for thermally managing mmWave antennas include forced air and liquid cooling. Despite being effective in removing the heat, active cooling systems with fans or pumps require the use of electricity and can make the system more complex and hard to maintain.
On the other hand, passive thermal management is a relatively cheaper and more energy-efficient solution. However, since the heat is removed only passively via natural convection using only heat spreaders or heat sinks, it is not easy to achieve thermal performance similar to that of the active counterparts unless there is sufficient surface area that is in contact with outside. 
In addition to modifying and creating various cell stations to carry 5G, carriers are also deploying edge computing resources to support such things as low-latency applications and IoT services. Edge technologies could one day make it feel like every 5G device is a supercomputer. Critical data is processed extremely fast at the brink of the network, by edge devices. Secondary systems and less urgent data are sent to the cloud and processed there. 
When designing 5G into a router or other fixed-access device, thermal issues will be a greater cause for concern than for products that use LTE for wireless communications, even though the energy-per-bit might be less than LTE because of 5G’s greater bandwidth.
An example here is the Cradlepoint W2000-Series 5G wideband adapter. The edge device was thermally modeled and then equipped with heat pipes to cool some internal components. Its aluminum case has integral fins and a white, reflective coating. 
Another edge computing hardware focus involving 5G is to support autonomous vehicles. Near real-time data transfer will be required for safe driving because transfer of large amounts of data to a centralized data processing plant will take too long, and this facility must use high-power AI algorithms to process the data efficiently and accurately.
Edge devices onboard vehicles will face harsh environments and extreme temperatures. This means a need for both solid thermal management and physical protection as well. Such a use case could call for thermal management with a chassis. An example is the Arrow SAM Car chassis developed to both cool and protect electronics used for controlling a car.
5G phones will be in great demand on a global basis in the near future. Ahead of all the 5G infrastructure installs, many 5G phone models are already available from major providers. This is not happening without growing pains. Some of the first 5G phones were found to be very susceptible to hot weather. Because of the overheating they would drop from 5G to 4G. This wasn’t isolated, but seen on tests of 5G phones from several major providers. 
Thermal issues increasingly challenge smartphone makers as processors get more and more powerful while phones get thinner and thinner. Some solutions, short of putting vents everywhere, involve thermal paste. Other conventional solutions could be heat absorbing materials and small heat pipes.
Samsung, Apple, and other companies can perform advanced thermal analysis to see exactly where hot spots occur, and devise strategies to mitigate them. These can range from better internal cooling solutions to thicker chassis or better thermal interface materials. Internal fans may be impractical for standard 5G phones, but even a very small fan could help with heat problems, at the cost of thickness, a bit of noise, and a little power. 
Data management may offer other remedies. Firmware could be developed to manage power levels and their associated heat. As mentioned above, it may be possible to have 5G phones offload some processing to nearby edge devices. While this may reduce heat in the phone, it may not be possible if different providers are running the edge gear and the phone’s operations.
Gaming smartphones are made to be super quick and super powerful, even compared to smartphones that already function at high speeds. Most phones can run hot when gaming intensively. But gaming phones have one advantage. They don’t need to look especially stylish, and so can get away with putting an air-cooling fan inside.
Nubia’s Red Magic 5G gaming phone features a small internal spinning fan to drive cool air in and hot air out. Nubia reports this results in cooling the phone by as much as 18 degrees Celsius, both while in heavy use and while charging at a fast 55W rate. 
From base stations to cell phones, 5G communications can dramatically improve mobile communications among billions of connected users. And more than this, 5G is a core technology supporting the evolutions in computing, life science, transportation and a near limitless range of applications. Like all technologies, it has some obstacles to get past, including high temperatures and their adverse effects. But 5G is too strong of a technical global game changer not to find solutions to problems along the way.