A Material Case for True 5G

5G networks represent a major leap forward in mobile internet connectivity. To enable these networks to be implemented successfully, here is an explanation why a key consideration is the use of 5G compatible protective materials.

Each new generation of wireless communication represents an advance in capability, connectivity and reliability. In less than 20 years, mobile internet connectivity moved from the 1G analogue mobile phone technology of the late 1980s to the 3G smartphone era of instant web browsing, video downloading and picture sharing. 4G emerged in 2009, offering greater speed and lower costs for voice and data services, multimedia and the internet.

Now the era of 5G is upon us. Whatever we do on our devices now, we will soon be able to do much better, quicker and smarter. 5G will enable a host of new capabilities, such as accelerating the Internet of Things, powering technologies as diverse as smart cities and remote surgery, and allowing autonomous vehicles to read live maps and interpret traffic.

The fastest 4G mobile networks offer average real-world browsing and download speeds of about 45Mbps (megabits per second), with a theoretical top speed of 300Mbps under laboratory conditions.

Chip manufacturer Qualcomm predicts 5G could achieve speeds ten or even 20 times faster. Average download speeds of around 1GBps (gigabits per second) could soon be the norm, with a theoretical top speed of 10Gbps. That’s the equivalent of downloading a two-hour movie not in 26 hours as with 3G, nor six minutes as with 4G, but in just 3.6 seconds.

ADDED BANDWIDTH, RAPID GROWTH

How will the extraordinary claims for 5G be realised? Even with the advances in rapid mobile connectivity offered by 4G Long-Term Evolution (LTE), the network is running out of bandwidth. Data congestion is already a problem in densely populated areas such as city centres and sports stadia. 4G LTE networks typically sit between 800 and 3,000MHz in the frequency spectrum. These lower frequencies are also heavily congested with TV and radio signals.

The solution is a frequency spectrum in the millimetre wave (mmWave) range between 24GHz and 100GHz, which have a very short wavelength. This section is largely unused, so the deployment of mmWave for 5G will greatly increase the amount of bandwidth available.

5G networks around the world are already capitalising on the opportunity offered by mmWave frequencies. According to IHS Markit, 31 5G commercial services had launched by the end of the second quarter of 2019. A key factor driving this rapid growth is the experience of the operators, who are drawing on lessons learned from 3G and 4G rollouts. A number of countries are emerging as leaders because multiple companies in these countries have deployed networks and are selling compatible devices, backed and facilitated by national agencies.

In the U.S., for example, the Federal Communications Commission is pursuing a 5G FAST plan designed to push more spectrum into the market- place, update infrastructure policy and modernize the regulatory framework.

Meanwhile, in China, three operators – China Mobile, China Unicom and China Telecom – launched the world’s largest 5G network across 50 cities in October 2019. Thirty-six percent of China’s mobile users are expected to be using 5G by 2025, representing a total of 600 million subscribers.

Other key markets include South Korea, where it took only 69 days for one million customers to subscribe to 5G services following the initial network launch; and the U.K., which saw EE, Vodafone UK, Three UK and O2 UK launch commercial deployments during 2019.

A high level of market readiness is also clear. During 4G’s first year of launch, only three smartphones supporting the standard were available to consumers. In 2019 alone, at least 20 5G smartphone designs were ready for release to the market.

THE CHALLENGES OF 5G CONNECTIVITY

The mmWave frequency spectrum transfers more data up to 20 times faster than 4G. In addition, 5G can support up to one million devices per square kilometre, while 4G supports only 4,000 devices per square kilometre.

Although 5G antennas can handle more users and data, they have a limited range. The fact that they only beam out over short distances requires new infrastructure to ensure coverage. This comprises ‘small cells’: miniature transmitters positioned about 250m apart in densely populated areas and employing what is known as ‘massive MIMO (multiple-input multiple-output)’ – multiple 3D directional antennas on a single station.

5G antennas will be located on buildings and street furniture rather than standalone masts. They will support non- line of sight (NLOS) operation by using a technique known as ‘beamforming’. A base station computer continuously calculates the best route for radio waves to reach each wireless device, then organizes multiple antennas to work together as phased arrays to create beams of millimetre waves to reach the device.

Beamforming works outdoors by reflecting signals off buildings, and indoors by reflecting off walls. However, many materials attenuate and reflect very high-frequency signals such as those in the millimetre wave spectrum, meaning that they are less able to travel easily through buildings or other solid objects.

A Sussex University report showed that at a frequency of 60GHz, this penetration loss was of ‘the order of some dBs for very thin plastic, wood or plaster partitions, -4 decibels (dB) for 0.7cm thick single-panel tempered glass and -25dB for a 9cm indoor brick wall’. What do these figures mean for a phone user?

MATERIAL IMPACTS ON SIGNAL STRENGTH

Signal strength is measured in decibels (dBm), expressed as a negative number. A reading of -50dBm is the strongest signal available (-50 to -79dBm would equate to 4 or 5 bars on a phone), while a reading of -110 to -120dBm would be a very poor signal (0 to 1 bar). The Sussex University findings therefore equate to an approximate 5.7 percent reduction in signal strength for the glass and a 35.7 percent reduction for the indoor brick wall – the latter turning an excellent signal into a poor one. 

There is a clear justification for individual and business purchasers of 5G handsets to optimize their investment by protecting it against accidental damage 

Other materials can cause path loss for a 5G signal. Rain or falling snow add an extra level of density to the atmosphere, thereby attenuating signals as they travel. The Sussex University study cites a maximum attenuation of about 30dB/ km for very heavy (100mm/hour) rainfall.

5G signal is even absorbed to some degree by air. Conventional frequencies can easily travel several kilometres whereas, even without any obstacles in the way, frequencies above 28GHz may only have a workable maximum distance of around one kilometre.

As explained in a paper published by BMS College of Engineering in India, ‘the atmosphere is full of gases that degrade the signal propagation along the propagation path’. However, cited research into atmospheric attenuation at different frequencies found that ‘the frequencies ranging from 28 and 38GHz encounter very small attenuation due to gas, providing feasibility of mmWave communication at such frequencies. It can be observed that negligible atmospheric absorption is encountered at 28GHz and 38GHz’.

Therefore, a key consideration in enabling the successful implementation of 5G networks is the use of 5G compatible materials, including within phone cases.  

OVERCOMING BATTERY DRAIN

All smartphones are designed to operate at the minimum power level needed to maintain a link with a cell tower. If a mobile signal is weak, the device will switch to maximum transmit power to try to establish a reliable connection. Although the extent of any resulting battery drain will vary according to the device, a general principle is that the weaker the signal, the more a device will need to work to improve its strength and quality.

As new device technology emerges, users may be unable to tell the difference between a good and a bad signal in terms of the quality of a phone call. However, this difference in signal strength will certainly translate through to battery levels.

Battery drain caused by insufficient signal is a real issue that can affect the speed at which 5G technology is adopted. Similar to electric vehicles, every obstacle to use removed will result in an increased likelihood of adoption.

PROTECTING INVESTMENTS IN 5G

The exponential growth in mobile technology has not only created an indispensable and defining element of our consumer lifestyle, it has enabled businesses to untether workers from their desks. A report from the International Data Corporation found that 86 percent of U.S. businesses were buying, deploying and managing smartphones for their employees with only slightly smaller numbers equipping staff with notebooks and tablets. The arrival of 5G will further amplify these opportunities.

The clear demand for the new capabilities offered by 5G technology will require investment, according to supply chain financier Greensill, of between $500 billion and $1 trillion for telecoms carriers to upgrade vital infrastructure alone. According to Greensill: ‘The most recent analysis of 5G spending... estimates the total bill for the 5G rollout throughout the global supply chain to top $2.7 trillion by the end of 2020 alone.’

The value of such levels of investment is rooted both in the belief that 5G will deliver what has been dubbed the fourth industrial revolution, and in the quality of the end-to-end 5G user experience. These explain why network operators are also putting aside substantial sums to bid for slices of the higher frequency spectrum required to offer 5G services.

WHY DEVICE PROTECTION MATTERS

5G device users have an important role to play. The mobility benefit of handheld devices is countered by the fact that they are significantly more at risk of being damaged than traditional desktop computers.

Devices provided by an employer are even more vulnerable than those purchased by individuals, who are most likely to bear the full cost of their investment. The International Data Corporation report cited earlier claimed an annual business smartphone failure rate of 13.9 percent, with the screen or display accounting for 70 percent of component damage.

Among non-business users, a 2018 survey, ‘The annual cost of broken smartphones in America’, found that 66 percent of U.S. smartphone owners admitted to damaging their phones with- in the last year, with more than 50 million phone screens accidentally smashed.

Owners spent an eye-watering $3.4 billion on damage repairs. Much of this cost could have been avoided had devices been properly protected with cases deploying impact resistant materials, such as those developed by impact protection specialist D3O.

The cost of damage repair could rise even further when more 5G devices enter the marketplace, given a highly specified 5G handset from a reputable brand is likely to cost in excess of $2,000.

BUILDING THE CASE FOR 5G PROTECTION

There is a clear justification for individual and business purchasers of 5G handsets to optimize their investment by protecting it against accidental damage. A key consideration is the material from which any protective casing is manufactured. 

Adding a phone case made of non-5G compatible materials to a 5G device could lead to dropped calls and slow data transmission 

This needs to be addressed in conjunction with the placement of antennas within the phone. Optimal placement is critical to their performance.

“Historically, antennas were mainly placed in the back panel of a phone,” says Kevin Fleer, Program Manager Team Lead for D3O. “As 5G will be used alongside existing 4G, 3G and Wi-Fi communication channels, there will in future be a multiplicity of antennas and they will need to be placed around the edges of the case as well as the back panel.”

However, positioning changes of just a few millimetres can make the difference between a well performing and a poorly performing device if combined with a phone case that interferes with the 5G signal.

The high frequencies employed in 5G networks have been shown to deliver what is called ‘dielectric loss’ when passing through even relatively low-density materials. The dielectric loss of a phone case material indicates how opaque to radio waves it is; the lower the loss, the stronger the signal. The materials used in many traditional phone cases for earlier-generation devices would, if used with a 5G device, attenuate and reflect millimetre waves to a detrimental extent.

As a result, adding a phone case made of non-5G compatible materials to a 5G device could lead to dropped calls and slow data transmission. An additional consequence would be poor battery life, with the device being required to work harder in order to find and maintain a good connection.

“Because there has never been an issue with consumers putting a protective case on a 4G phone and losing signal strength,” says Fleer, “there is a lack of awareness that the situation is different with a 5G phone. Consumers will need to know what they should buy and have confidence that a product they choose will be reliable.”

This view supports the findings in a 2018 report by PwC, ‘The promise of 5G’, which states that reliability is the foundation on which 5G must be built. Consumers placed reliability at the top of their ‘must have’ list when using a mobile device, ahead of unlimited data, security, cost and speed.

Should cases advertised as 5G compatible prove not to be the case, the potentially negative consequences could damage consumer and business trust at a critical point in 5G roll-out.

RESPONDING TO THE CHALLENGE OF OPTIMIZING 5G PROTECTION

What is the approach to resolving this issue without resorting to short-cuts or the need to lean heavily on lower frequency bandwidths? A deep dive into materials science to address the root cause of dielectric loss leading in turn to signal loss, with the aim of developing a material solution that is genuinely 5G compatible.

By using case materials that act as a mesh for 5G signal to pass through, consumers will be able to protect their investment and truly benefit from the faster connections and data transmission speeds offered by the new technology. Permittivity is a measure of how easily electric lines of force can pass through a material. By definition, a perfect vacuum has a permittivity of exactly 1. In the example of a phone case, the lower the permittivity of its materials, the stronger the signal that can pass through it.

‘External cases create distortions in 5G mmWave antenna radiation pattern; peak gain [a measure of input power concentration in the main beam direction] and spherical coverage [the range of solid angles that a piece of user equipment can cover] profiles are altered,’ confirms Samsung. ‘This negative impact can be reduced by using thinner cases (less than 3mm) with low permittivity materials.’ 

MEASUREMENTS

D3O worked with an external laboratory to obtain measurements for dielectric permittivity and signal loss that could then be used for analysis. The outcomes were twofold; 

• First, to measure the permittivity of various phone protection materials at different frequencies; and 
• Second, to measure any loss of signal from these materials.

The materials under review included those used in existing phone protection products, plus D3O with 5G Signal Plus? Technology. This material employs micr ovoids to increase the air content of a phone case, on the basis that air enables a 5G signal to pass through with minimal loss in terms of both strength and quality.

“D3O has been developing different thermoplastic elastomers (TPEs) for phone cases since 2015,” says Richard Holman, Material Development Leader at D3O.

“Once it became apparent that 5G would experience some technical challenges around signal loss, and that these could be exacerbated by adding a non- 5G compatible material to a case, D3O saw this as a unique opportunity for its materials development specialists. “Permittivity is an established property of a material,” Holman adds, “Measuring permittivity using plaques [small slabs] of different materials is a factual check and is repeatable.

“Permittivity is mentioned in the 5G specs issued by major phone manufacturers, so it was the first port of call to see if various materials, including D3O with 5G Signal Plus? Technology, were meeting these specifications. All the measurements were done on plaques of materials so any design element was disregarded. It was purely a test to demonstrate which was the most appropriate material.”

“The testing for signal strength took almost two months to set up and establish the parameters” says Fleer, who managed the Signal Plus? development project. “Then the measurement process took another month with technicians in a temperature controlled, radio frequency, fully anechoic chamber taking readings. The objective was to obtain data from a specialist lab.”

BEATING THE PERMITTIVITY BENCHMARK

The benchmark originally set by Samsung was a permittivity at 5G frequencies of less than 2.5, allowing phone case manufacturers to have a level to work to in order to claim true 5G compatibility.

Techniques to determine material permittivity vary according to the frequency of the signal. The measurement methodologies for material permittivity were as follows:

• 4G and sub-10GHz 5G frequencies were tested using a split-post dielectric resonator (SPDR). This device is widely used to measure the permittivity of dielectric laminar specimens in the 1-10GHz frequency range. D3O tested at 1.8GHz and 10.2GHz.
• For targeted 5G frequencies in the 26- 39GHz range, no equipment is currently available to test low loss materials at these frequencies. The closest result is obtained using Lynch’s formula, which allows the calculation of any change in permittivity for a given change in frequency using dielectric constant and loss values from 1.8GHz and 10.2GHz.
• For longer term 5G frequencies (50GHz), testing equipment is available. However, permittivity decreases with higher frequencies. This means that any material failing to pass the benchmark figure at 50GHz will fail at 26-39GHz.

Analysis of the measurement data obtained found that D3O with 5G Signal Plus? Technology was the only material to meet the most stringent specification for permittivity at 5G frequencies, allowing stronger signal to pass through.

DEMONSTRATING IMPROVED SIGNAL STRENGTH

A number of existing phone protection materials, plus D3O with 5G Signal Plus? Technology, were also tested to measure any loss in signal. This is another essential element in optimising 5G protection because, as Holman explains, it shows what the actual effect would be of wrapping a material around a phone.

As previously stated, the only reliable way to determine the absolute strength of a signal is to take a reading in decibels (dBm). In order to achieve completely accurate data, the tests conducted used a mmWave 5G software defined radio, a vector network analyser (VNA) and the anechoic chamber mentioned earlier. 

D3O with 5G Signal Plus? Technology... was best suited to meet the most stringent specification for permittivity at 5G frequencies 

The distance between transmitting and receiving antennas was set at 0.5m to reduce the edge fringing effect on the transmission loss measurement due to the size of the material sample, which was itself positioned at different distances from the front face of the receiving antenna. The transmission loss between transmitter and receiver was then measured by using continuous wave signals and the VNA.

“As frequency increases, permittivity decreases in an almost linear path,” Holman explains. “Signal loss, on the other hand, can go up and down. What we were checking was that there was no peak in the loss at the frequencies we were testing – that is, the 26-39GHz 5G frequencies.

“The measurements carried out provided levels for permittivity and for dielectric loss. So, if your aim is a material that is 5G compatible, even if you get good permittivity you don’t want to see a spike in dielectric loss at the frequency you’re interested in.”

Analysis of the measurement data obtained found that D3O with 5G Signal Plus? Technology achieved on average 37 percent less signal loss than its nearest market competitor and outperformed all benchmark materials. This equates to a 10 percent stronger received signal output for consumers, enabling the fastest download and upload speeds.

Analysis of Variance (ANOVA), a statistical method used to test differences between two or more means, verified a meaningful difference in mean transmission loss across the measurement distances and materials tested.

CONFIRMING IMPROVED BATTERY LIFE

A stronger and more reliable signal enables optimal browsing and multimedia viewing. A stronger and more reliable signal also means that a phone needs to use less power to find and retain that signal. A 2013 Cambridge University research paper, ‘Characterizing and Modeling the Impact of Wireless Signal Strength on Smartphone Battery Drain’, was the first measurement study of 3G and WiFi signal strength experienced by a large number of smartphone users over a long period of daily usage.

The paper took as its proposition: ‘Poor wireless signal strength not only affects network performance, but also – in the context of energy constrained mobile devices perhaps more importantly – can significantly inflate the actual energy consumption by the wireless interface to be much higher than under good signal strength, while transferring the same amount of network traffic’.

The users that were studied carried out an average of 43 percent and 21 percent of their foreground data transfers during periods of poor 3G and WiFi signal strength. A sample finding was that in order to complete a 100 KB download using 3G at a signal frequency of -85dBm to -95dBm, energy consumption increased mildly by 6.6 percent. With a much weaker signal of -105dBm, energy consumption to complete the download increased by a massive 52 percent compared to consumption at -85dBm.

Given that D3O with 5G Signal Plus? Technology suffers less average signal loss and delivered a stronger signal output, it follows that a 5G phone placed inside a case made from this type of material needs to use less power to find and retain a signal. This positive impact on battery life plays its part in delivering the high-quality user experience one would expect from a 5G device. 

PROVIDING TRUSTED PROTECTION

At this point, the primary function of a phone case needs to be remembered – that is, to protect the device from drops and other accidental impacts.

D3O with 5G Signal Plus? Technology leverages the micro voids introduced into it in order to meet the most stringent specification for permittivity at 5G frequencies while being engineered to provide superior impact absorption.

“Our objective with this material was to match the impact performance of our current best-performing TPE,” says Holman. “In fact, when analysed using a standardised drop test on a phone case, the results showed that D3O with 5G Signal Plus? Technology exceeded the performance of D3O’s existing, market-leading materials.”

DELIVERING THE SOLUTION

For anyone seeking to reap the benefits of 5G, choosing the right phone case, made from the right material, is paramount. “A 5G compatible material that delivers better reception, faster connections and better battery life is a compelling proposition,’ says Holman.

In contrast, an unreliable signal caused by an incompatible case can lead to the frustration of dropped calls, slow data and poor battery life, as a result of the phone having to work harder to track down and sustain a good connection. A user might well end up questioning why they bothered to invest in 5G in the first place. Tests have shown that a material providing maximum void volume while retaining maximum strength is best able to deliver the necessary dielectric effects for optimal 5G signal reception.

D3O with 5G Signal Plus? Technology has been proven to meet the most stringent specification for permittivity at 5G frequencies. Using the lowest permittivity material enables design of the most 5G compatible case.

With an improved signal, faster download speeds, enhanced battery life and the best ever impact protection, users are equipped to capitalize on the full potential of 5G technology to deliver the promised leap forward in mobile communication.