Does sensing in 6G make sense?

stein@opensky

I have on several occasions earlier commented on 5G and 6G and their use cases – and here is another go – specifically on 6G and the perspectives on “ISAC” (Integrated Sensing and Communications). Some of my earlier comments have included the realism of using THz spectrum (see here from 2021 already), the challenge on focusing on B2B rather than B2C (a “G” needs economy of scale) – and the fact that someone has to build the network (typically an operator) – and they need a business case to do it. See also my earlier article from January on “Making 5G a success – or waiting for 6G?”, commenting on the timeline for 6G - which clearly needs to be extended beyond 2030. A more general perspective on 6G can also be found in my article from July on “6G – set for failure or success?”.

With all the above articles indicating a lot of skepticism, I will this time have a look into the topic of ISAC, which is a key area in scope for 6G, with an open mind. Until now I have not fully understood what it is all about – but let us see.

The research and standards communities have been working on 6G for some years already. NGMN has made several position statements and reports on it, 3GPP has defined a timeline for the standard (first release R21 in late 2029), the ITU keeps on referring to “IMT-20x0” variants, of which 6G is IMT 2030 – and ETSI has produced a good report on “Integrated Sensing And Communications (ISAC); Use Cases and Deployment Scenarios” (as can be found here). All the telco vendors (like Ericsson, Nokia, Huawei etc) are also all betting on 6G – as they all need another ”G” to sell.

There is no doubt that 6G will come, as so many people are working on it. The question in my mind, however, is whether it will take off and be the success many people are dreaming of. It is also a fact that 6G is not only for operators and telco vendors – as a “G” used to be some decades ago. There are many other players with a stake in it. For curiosity, please see an overview of “G”s in my table below – where you can see how “G”s have been developed over time, the beneficiaries and who have been driving it.

What is ISAC about?

The key word in ISAC is “sensing”, i.e. that the mobile network senses what is happening with or around a user or a device. Many use cases are outlined in the referred ETSI report, however, to summarize: Only some of the potential use cases are for consumers. Mostly they are for vertical industries or the Government. Some of the potential Government use cases are for public health, smart cities, emergency search & rescue, disaster control, environment monitoring etc, which are all good, but some of them could also have privacy concerns.

Looking through examples of what has been referred to around ISAC use cases, it is very much about object detection and monitoring, environmental monitoring (rainfall, weather prediction, pollution etc) or motion monitoring (3GPP). Examples of objects can be drones, robots, cars - or even people or animals.

Of relevant use cases mentioned for a consumer can be home appliance control (smart home), detection of intruders (home security), detection of breathing or hearth rate - or fall detection (health monitoring), driver attention e.g. falling asleep (automotive) etc. Although these all may be of interest to a consumer, the typical perspective is not B2C but B2B2C as seen from an operator. There are also possible consumer use cases focused on motion control or gestures, like virtual piano or keyboards – or gesture recognition in general. Extended reality (XR) and gaming are also of relevance – and holograms could be an interesting (high-end) feature in person-to-person communications.

On the industrial side, some key sensing use cases may include autonomous driving, 3D vision, digital twins, accurate positioning etc – many of which were also hyped around 5G – like also remote surgery and industry automation. Many of the use cases around ISAC may benefit from the use of THz or mmWave spectrum. Quite a few also assume the use of AI.

Security and privacy

Some have stated concerns around 6G and sensing, in the sense that “Big brother is watching you” and that “you are the product”. This is not new, as it is something that big tech (i.e. hyperscalers, “OTTs”, etc) have been doing for years already – with business models based on advertising capitalizing on information about you and your habits, activities and interests. “If you are not paying for the product, you are the product”. Marketeers are already thinking about how to exploit this further with 6G and sensing (e.g. Digital Resource).

So what could this be about? With 6G we will see not only that everything will be connected, but also that the network potentially will detect you, your movements and everything around you – “in a hyper-connected world where everything and everyone can interact in ways we have only seen in Sci-Fi movies”. “It will push the boundaries of what’s possible in how we connect, communicate – and market”. With the addition of AI on top (which is planned as an inherent feature in 6G), everything about you can be analyzed and personalized into truly personalized marketing.

On top of the marketing dreams, a feature sometimes referred to around sensing is for crowd monitoring. This may obviously be used for good purposes, however, in certain less-democratic countries this could clearly be used also for personal surveillance and control of the masses (already in use today in some countries – but possibly worse?).

If we also consider security aspects around sensing, although security features in 6G most likely will be better than in 5G (as 5G features also were compared to 4G), the introduction of sensing as a new technology will add to the threats and attack surface for the network. Of course, AI may be used as a countermeasure but also to augment the threats. Some examples of new security concerns could be false detections, time/phase manipulation (as we already see in Northern Norway close to the Russian border for GPS / GNSS) etc.

Practicalities and business sense

ETSI, 3GPP and lots of research departments around the world are all looking into the various use cases and technical aspects of ISAC (as e.g. in the ETSI report referred above). Others have, however, voiced various concerns around related practicalities. William Webb (see here) has, for example, referred to the complexity and cost of it, due to the potential needs for a full duplex radio channel, very high bandwidths requiring high spectrum (e.g. mmWave or THz) and the unsuitability of OFDM for sensing. Vish Nandlall offers similar concerns here.

It may be that the technical and practical aspects of sensing in 6G will be solved (whether perfect or not). My concern is more around the business aspects around it – and it is basically around who will want it (and want to pay for it)? … and are there alternative technologies that can do it better? It might be that the military or airport authorities etc will be willing to pay for detection of drones. It might also be that public health services would want (although not pay) for certain features. Governments may also want (although not pay) for certain emergency services, environment monitoring etc. In many cases the ISAC use case is also probably localized and could be for an operator in a local B2B scenario and/or with private networks. Making a wide area ISAC coverage probably has no business case.

As stated already initially above, most ISAC use cases are for vertical industries or the Government. For consumers and large-scale solutions, I see fewer opportunities. There may be companies wanting to offer sensing-based services to consumers, but from an operator perspective, this is B2B2C and whatever the use case is, be it for smart home, home security or fun-oriented cases like gaming and XR, the local network will need to have ISAC functionality – and the operator will need a business case to build it. As also commented on by others, e.g. like Vish Nandlall and William Webb above, there might be alternative technologies (like e.g. radar) that can do the job better.

Summary

Although I have been part of the mobile “G” race some decades ago, I see that the general trend ever since 3G of making every new “G” into more of the same – just better – and then adding some new features to it as well. For 6G this would be sensing. The trend of designing “universal singing and dancing machines” keeps going further within the 3GPP community. For reference, see my article already from July on “6G – set for failure or success?” – covering a lot of aspects around “G”s and 6G in particular. Basically, a challenge is the 3GPP community having too many contributors (and politicians behind the scenes with good intentions for their communities, e.g. for transport, health, industry – or even geopolitics), each with a different and specific interest, thus ending up with a total solution which covers everything - and which takes too long to develop and implement.

Some operators have seen the challenge, like e.g. the Verizon CTO here, requesting to simplify and unify the 6G standard to avoid too many options like e.g. 5G has with SA and NSA etc. Operators today, however, struggle to control the standards process. I would not be surprised if ISAC ends up being a 6G phase 2 – since it is all too complex and “special”. In any case, my view is that even “6G phase 1” in 2030 is too early.

To get to the case of ISAC specifically, it unfortunately looks like a technology looking for a use case – and honestly, I don’t see the killer app in anything that I have seen so far.

6G and sensing will result in an even more intense data generation about you, opening up for data-driven marketing and services – with AI-driven personalization (or surveillance). The privacy aspects around 6G will probably need to be looked further into. However, I am not sure this has been seen yet by politicians and regulators. It might end up as an after-thought, if at all ISAC is anything that will take off (?)

All in all, 6G will come, but probably several years after 2030. So will ISAC, but I am not sure it will have any commercial success. There are noble ambitions around it, but I cannot see who will pay for it – or if there is a business case for a network operator implementing its functionality. Maybe in a private network? As it is technically complex, it could also risk delaying 6G as a whole (maybe not too bad?) – so it might end up as a 6G phase 2 – or maybe it should simply be dropped (?) for the benefit of alternative technologies.

There may be things that I have missed – so let us see what happens. I am skeptical though. Does sensing in 6G make sense? I am not sure.