The International Telecoms Union has defined what it sees as 6G, which it will seek to develop standards for through 3GPP. Integrated Sensing and Communications [ISAC] is one of three capabilities which are unique to their vision of 6G, as opposed to elements which are extensions of 5G.
That said, it is likely that some early elements of ISAC are likely to find their way into standards for 5G-Advanced. Work on ISAC is being pursued pragmatically and with an aim to deliver services which are useful, but which will require a minimum of investment to deliver.
What is 6G Integrated Sensing and Communication?
Waves in the radio spectrum have historically been used in different ways. Radio can carry communications information, as we have done in radio broadcasts and person-to-person in mobile communications. However, even in World War Two we were using radio waves to locate aircraft, in the form of radar.
The evolution of radar and communications has been quite distinct up until recently; not too surprisingly, as the use cases for each have been quite different. Radar has typically operated at low frequencies which can deliver a long effective range. However, the trade-off for radar has been that of detail: a low-frequency signal will carry for miles with little attenuation but cannot provide much detail about what is being spotted. Good radar operators may be able to interpret the radar ‘signature’ of a type of aircraft to identify it, but that is far from being able to ‘see’ the aircraft. For air traffic control purposes, though, that has not been relevant.
In communications, however, a drive towards higher frequencies has been necessary to open up more bandwidths. As communications systems have been moving to higher frequencies, it has had several consequences:
- The effective distance of communications has reduced as things such as oxygen in the atmosphere can absorb high frequency signals. As a result, 5G and Wi-Fi are able to deliver high quantities of data but over relatively short ranges.
- At higher frequencies, the level of detail available by using radar techniques increases dramatically. This would enable radar to go from creating a ‘ping’ to being able to recreate shapes and structures with some accuracy and understand if they are moving and how.
What Is the Point of 6G ISAC?
ISAC in 6G will open up a variety of new roles for telecoms companies to play in partnership with other industries. This will help create new models and potential revenue streams.
While there are many possible stages in the development of ISAC, the fundamental point is to create new uses for the signals which are already all around us.
How Does ISAC Relate to Joint Sensing and Communications [JSAC]?
JSAC is a technique which draws information from different kinds of source – video data from CCTV cameras, let’s say, and communications data from a 5G cell – and combines them. This combined set of data offers advantages in a variety of ways. As Alain Mourad, head of ETSI’s ISAC working group, noted in this article:
“The sensor data is useful to the network to improve the network performance – better beamforming, if you like, or better delivery of a service. But it also works the other way around. So, you know, the communications can also feed information into the sensor system.”
For a CCTV company, information from the communications signals could be used to compensate for visual mistakes caused by, for example, camouflage or a trick of the light.
The integration of communications and sensor data in this situation is relatively straightforward technically. It doesn’t require any changes to the hardware itself. At a software level, finding the right ways to share data and process it in useful ways is the most challenging element.
ISAC, in contrast, would not require a separate sensor system. Both the sensing and communications can be done within one network.
6G Integrated Sensing and Communication Use Cases
The ETSI ISAC group has identified more than 30 possible use cases for ISAC with the help of partners in other industries. In the long run this is likely to be non-exhaustive, although it is very much still to be seen whether any of these use cases will translate to live business models. The fact that the use cases were developed in conjunction with potential clients is promising, however. Use cases fall into three types:
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Wide-area ISAC deployments
These would rely on a whole cellular network across a country or region being ISAC-capable.
While radar is effective at managing aircraft, at lower levels radar coverage drops out. Meanwhile the number of obstructions increases. As a result, tracking and detection of drones could be a very useful aspect of cellular-based sensing. This can, for example, detect drones in (or likely to invade) sensitive areas such as airfields or other prohibited airspace.
Additionally, ISAC could be used to assist with drone tracking to avoid collisions and create a traffic management of the skies. In many countries today, drones have to be flown within line of sight of an operator simply because the risks involved in ‘flying blind’ are very high. Instead, it would be possible to set up a drone traffic management and routing system across wide areas to allow drones beyond line of sight.
On the roads, ISAC could be useful too. While autonomous vehicles by definition don’t require external communications to function, “V2X” communications between a vehicle and its environment offers many advantages for coordination and safety. Using ISAC-capable systems adds further richness to these. ISAC-capable systems, for example, can be used to identify obstructions or oncoming traffic around the corner from a car – which can be very useful in some rural situations, not least where the obstructions might be moving, such as a horse or pedestrian.
There is a similar argument for railways, where being able to identify a person or animal on the tracks ahead of a train might give enough time to brake – something which all too often can lead to tragedy.
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Indoor or restricted-area ISAC deployments
ISAC can be used indoors to track in detail where things are as well as communicate with them, for example as an upgrade on a private network.
This can help with the coordination of robots within a factory or warehouse setting, for example. And, while robots may have sensors to help them avoid collisions, in busy or unpredictable environments where robots are surrounded by people and vehicles such as forklifts, this would improve safety and reduce risk for all concerned.
ISAC can also be used to help identify and locate inventory, which can be a challenge especially in larger sites. While a car may have a GPS tracker, a trolley probably would not.
ISAC could also be used create and maintain a live digital twin of an environment. Let’s take the example of a hotel: the resolution available would allow the digital twin of a hotel to also have twins of the people in it, updated in real time, without being detailed enough to identify the individual. This could have multiple applications:
This would let housekeeping know which rooms to avoid while maintaining privacy. It would enable managers to keep track of how people move around their hotel and identify opportunities to optimise the experience. They could create apps to tell guests how busy a restaurant or pool is in real-time. In the case of a fire, it would also be a useful way to identify where the fire service should prioritise rescuing people.
ISAC could also be used as a complement to AR or XR. AR uses volumetric data to understand the world around and add elements on top. ISAC could be used to complement this – or replace it, in the case of somebody with VR glasses.
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ISAC for improving communications
While ISAC can offer value to other industries, information about the environment can also help improve telecoms services. For example, high-frequency broadband communications can be blocked or interfered with by a car or other objects getting in the way of a direct beam from base station to the receiving device. If the telecoms system is aware of, for example, a car that is about to block a signal, it could proactively change the cell tower the device is communicating with or switch to a lower frequency with a better ability to penetrate the car.
ISAC Resources
6GWorld will, of course, keep you up to date with the latest news on ISAC. However, here are a variety of other basic resources you might find useful:
- ETSI website on ISAC
- IEEE’s ISAC emerging technologies initiative
- Ericsson ISAC explainer
- Huawei ISAC “From Concept to Practice”
Further Possibilities With ISAC
While the technology for radar is fairly well understood, integrating ISAC will still be a process and there are technology developments which are further away from realisation, but which might eventually have useful impacts. The following areas of study are being worked on within ETSI but may not feature in 3GPP standards, certainly not early on. Areas of study include:
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Advanced Radar Cross Section modelling (ARCS).
This deals with identifying objects of complex shapes and structures and materials as opposed to very basic kinds of shapes and materials.
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Microdoppler.
Microdoppler has to do with vibration and rotation of objects – any kind of micro motions. If ISAC is capable of picking up on microdoppler movements, this could be applied in a wide variety of ways. It could be used non-invasively to detect pulses in humans, or to monitor the vibrations in factory equipment which can be used to check their state of wear.
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Near Field ISAC.
Typical cellular base stations are designed to deliver communications over as long a range as possible. However, very close to the radio antennas there is an area, the “near field,” which creates its own challenges in terms of managing communications. We might liken this to how a cat’s eyes work. They can see with great acuity over a distance, but within a few centimetres of their head they cannot properly focus.
However, the ISAC ISG is exploring the use of spectrum in the 7-24GHz range to deliver both communication and sensing capabilities in the near field. This would ensure that there are no ‘dead zones’ where services fail.
Spectrum Needed for ISAC in 6G
Fundamentally, ISAC does not require any additional spectrum which is not already allocated to telecoms or is being considered for future telecoms services.
There are two ways for ISAC to operate. According to Mourad, the first would be to run sensing in one piece of spectrum and communications in another, both of which the operator already holds – for example sensing in mmWave and communications around 6GHz – then combine the data.
However, “The ultimate integration level that everybody would like to see is where it’s exactly the same frequency, same spectrum, the same transceiver chain, the same system and delivering both capabilities,” said Mourad.
The reason is simple; this offers greater efficiency for the telecoms provider. They have paid for all their licensed spectrum, so if they are able to use all of it both for communications and sensing then it gives them the best possible usage for their license.
Security and Privacy Concerns with 6G ISAC
It is one thing for a carrier to be managing information about their own subscribers. However, with ISAC data is being created about more or less anything in the environment, regardless of whether it is a customer or even aware of the scrutiny. Particularly when applied to a national-scale network this can seem massively intimidating to end users.
However, the sheer amount of data that ISAC could create would be absolutely overwhelming. Sending that data to the core network for processing, storage and more would impose a huge overhead on networks which already struggle to come with current levels of data growth.
ETSI is exploring an approach which might solve both problems. The trick would be not to focus on sensing data, but on the “sensing result,” according to Mourad. Rather than sending every piece of data back to a core network for processing and storage, processing would be done locally. Then only relevant information would be sent onwards.
For example, consider a railway using ISAC. Most of the time data generated about a stretch of track will be absolutely useless. What they need to know is if something changes, such as a person or animal walks onto the tracks or a landslip shifts the rails. In this case, the sensing result might be “Person on the tracks!” They don’t need to know who that person is, what they look like, or anything else in order to take the appropriate action.
“Typically the sensing result is light from the data point of view,” Mourad confirmed.
However, he pointed out that there are still many questions around how ISAC data can or should be approached which are works in progress:
“Compressing the data, preprocessing the data, extracting different sensing results, different nodes analysing that data, exposing that sensing result or sensing data to which entity, which node, or which device.”
Indeed, ETSI’s total work on ISAC falls into three work streams, and one of those is focussed on managing privacy, security and sustainability.
