Amidst all the talk about Beyond 5G (B5G) deployments and the expansion of the 5G ecosystem, one of the primary topics for discussion is how to manage the ever-increasing appetite for power in this emerging wireless space.

Concerns have been raised that the global power demand for 5G is going to be significant – and even worse for B5G. That has led to a movement to tame the power demand, across all platforms and technologies, to its most efficient state.

Once we approach the 6G threshold, hopefully 5G will have taught us many lessons on ubiquitous device connectivity and the challenges that go with powering this ecosystem. This means not only looking for new solutions but revisiting existing ones as well. This paper will take the reader on a walk down the path to 6G and examine some of the options. Mind you, this is by no means a comprehensive or all-inclusive overview of what may be on the horizon, but it does touch on some of what is emerging.

Some platforms are not as problematic as others. For example, smartphones and other portable mobile devices, autonomous vehicles, fixed installations, UAVs, and so on will simply continue their existing battery- or grid-dependency for the near future. These devices will continue to see technical improvement in power efficiency and conservation (for example, with the work the NGMN is doing on lower-power networks), but the bigger challenge lies with remote devices such as antenna sites, sensors, Internet of Anything/Everything (IoX) devices, security and military devices, and even fledgling technologies such as motes.

The proliferation of wireless devices will create a new order of magnitude in power demand. Many of these devices will require power to be manufactured locally. And, with the exponentially expanding IoX, new power challenges will emerge in nearly every sector and platform.

Some solutions are relatively obvious and straightforward. Recently, Ericsson’s 2021 mobile report noted that at the forefront of energy awareness is efficiency. They note several points including placing sites with efficiency in mind, using the latest technology solutions, activating energy-saving software, building 5G and 6G solutions with precision, and operating site infrastructure intelligently. So, going forward, efficiency in power design will be as fundamental a requirement as security by design.

Some of this is not rocket science. However, the decisive factor across just about everything is cost. Although implementing these savings is desirable and, in many cases, already possible, there is always the looming issue of how it affects the bottom line. Telecoms energy costs vary considerably; however, it is an energy-intensive industry, with power costs currently contributing anywhere up to 7% of a telco’s operating costs and accounting for 2-3% of a country’s total energy consumption according to this 2020 McKinsey report. While we all want to throw the latest and greatest efforts at reducing power consumption, ultimately telcos will have to spend less to deploy these technologies than they save on reduced power spending.

Power Sources

So what are some of the solutions for this brave new world of power management? Obviously, solar and wind are the leading contenders for many situations, applications, and devices (at both macro and micro scales). They are realistic and workable solutions and constantly undergoing advancements. But they have obvious limitations in source reliability. Nevertheless, wind and solar will scale and be among the most prolific solutions as we expand our energy appetite across all segments and industries, not just B5G.

Beyond wind and solar (which of course are part of the energy harvesting ecosystem), new frontiers are being broached in the micro- and milli-energy harvesting segments. This space has been active for decades. However, it has a major drawback not common to wind and solar. Micro- and milli- energy harvesting methodologies tend to exhibit very low power outputs (see this article for an overview of some of the technologies and applications of micro-energy harvesting). But, as this field advances, these micro-harvesters hold tremendous promise for some segments of both 5G and B5G. More on these later.

Ingenuity already abounds on the macro level, however. One example in the telecom space is a collaboration by Vodafone and Crossflow Energy, which has a technology called Transverse Axis Wind Turbines. This is a new take on the mature wind turbine technology, with blades resembling more of a paddle than a propeller. They are said to be more efficient and reliable than standard propeller generators. Vodafone plans to use them, in combination with solar and battery tech, to make self-powering masts.

The significance of this is that these devices are much smaller than the typical wind turbines and can be used to power sites that normally would require grid power, without being so challenging for local planning approvals.

Their impetus behind this has to do with the digital divide and rural spaces. All around the world, there are areas with little to no connectivity, and the difficulty and expense of building masts and base stations in remote areas can be uneconomic. Vodafone’s approach, if it works, is certainly admirable and brings wind power generation down to a more granular level.

While the project is still in the proof-of-concept stage, Vodafone believes deployment can begin by the end of this year. However, all that glitters is not gold and while this is a commendable approach to both energy conservation and their bottom line, it is still environmentally married to the wind, which is not always available. So they are backing that up with the usual suspects – batteries and solar.

Battery Replacements

Now, drilling down on the other side of the power scale is something being pioneered by Ericsson and MIT. It is called zero-energy technology (ZET). This is in the realm of micro-to-milli energy harvesting.

Consider the fact that both 5G and beyond will see an explosion in Massive Machine-Type Communication (MMTC). These devices generally are low-power and low-bandwidth devices, in the neighbourhood of a few hundred kbps maximum and low on power states. And the prevailing use case for such devices is in the narrowband Internet of Things (NB-IoT).

A common example of this is remote meter reading. Currently meters tend to be powered by a battery. Although the battery life of this, and other NB-IoT devices, can be up to ten years under optimal circumstances, actual battery life – and the need for replacement – depends on a variety of conditions. Overall battery life is dependent upon Tx/RX, and on/off duty cycles, as well as the environment. Depending on the application and the location, battery life can vary wildly. In more remote situations battery maintenance can already become cumbersome.

As the IoX explodes, and hundreds of millions of devices turn into hundreds of billions, these battery management challenges ratchet up by orders of magnitude as well. Looking at it from that perspective, the reason for finding a better and maintenance-free power source is obvious.

There is a movement to replace the battery in such devices with micro-energy harvesting devices (the ZET initiatives). This approach eliminates the battery (or relegates it to backup status with a much lighter footprint) and draws its power for operation from its environment – vibrations, light, temperature gradients, wind, even from the radio-frequency waves themselves.

Couple this with advancements in low-IQ power management blocks and other power optimization technologies, and where battery backup is employed, their life can be extended by as much as ten additional years. However, the goal is to eliminate batteries as extensively as possible.

In the future, across the B5G landscape, ubiquitous zero-energy devices will be the goal whenever possible. Potential applications include pollution monitoring, weather sensors, disease prevalence monitoring, wearables, patient monitoring and many other wireless applications.

Such IoX devices will even find their way into the retail sector. For example, a customer picks up an item and immediately the energy-harvesting embedded device notifies the store network that the item is being explored. Next, all the video screens around you light up with competitive offers or similar items that may interest you (and you thought current targeted push-type technology is invasive!).

But the point is that this is not science fiction, even though there are many challenges to bringing this to commercial fruition on a large scale.

RIS

Finally, perhaps the most exciting future energy direction lies with reconfigurable intelligent surfaces (RIS – also called hypersurfaces, intelligent reflective surfaces – IRS, and software-programmable metasurfaces – SPM). Some of these can be ideal candidates for zero-energy platforms. Currently research is focused largely on the Terahertz domain but other use cases will emerge as this platform evolves.

One current research project uses active Terahertz components and metamaterials in arrays of separately programmable “tiles.” These redirect, amplify, collimate, polarize, and otherwise manipulate Terahertz beams.

RISs are also likely to play a significant role in the enhanced mobile broadband (eMBB) segment of B5G. Here attention is focusing on cell-free networking, removing infrastructure components currently used in cellular networks and cutting their power demands. This is an exciting topic that promises to alter the energy footprint both of mobile devices and of existing networks.

Other platforms such as NB-IoT, M2M communications, wearables, medical devices and so on are also able to push closer towards zero-energy solutions using RIS platforms along with energy harvesting.

There are so many more possibilities within the power awareness ecosystem. This short paper only serves to present some of the possibilities. The next level of power management technology is just around the corner, and it is across all power scales – from micro to mega.

The need for energy conservation is a no-brainer. If current energy approaches continue and the number of devices multiplies by orders of magnitude, the energy supply will be unable to keep up with the demand at some point.

But there is a bright horizon and some of the best minds around the globe are beginning to look at power conservation and reduction technologies. At some point in the future, everything that is power-dependent will be power-conservative. That is a given.