In this Mobile World Congress (MWC) session, Alan Carlton, senior director of InterDigital Labs and head of InterDigital’s European office, hosts a discussion with IMEC program director for wireless communications, Dr. Liesbet Van der Perre, and University of Aveiro professor Dr. Rui Aguiar, a member of the Board of the 5G Public Partnership Project (5GPPP) , on the topic of 5G technologies. Alan: What do you both see as the key driving requirements for 5G that are emerging today? Rui: Good question. I believe the key word is freedom. We are witnessing a huge amount of discussion about what 5G is about, and we always have to ask, “What would be the added value?” Most of the time, if you ask what people want, it is the ability to be free to choose their operator, to choose their technology, free to be able to roam without being concerned if they are paying more and free to be able to actually lead their normal life without actually considering or thinking about technology. Liesbet: From the technology side, I like to hear that, but there are also reasons why we can't just fulfill all the future requirements that users and non-users, like machines and other devices, will ask of the technology and wireless capacity. We need to boost capacity because of the quality and variety of services. And maybe that's the freedom you're talking about as well, the variety of services needs to go up. The capacity needs to grow by a factor of 1,000, and with just more 4G, that will not work. We really need to rethink the systems and come up with some new solutions because services need to become better. More and more devices will be there; more applications will be there. We need another kind of solution, another kind of networking. Rui: Jumping on what you just said, this notion of 1,000 times more capacity is mostly the notion of bulk spectrum. One of the things that will differentiate 5G from what we have today is that this is the spectrum of the whole without any kind of intelligence. You mentioned machines and more advanced services. And all these things actually will start to explore, in an intelligent manner, the spectrum. So, we will need to revisit spectrum thinking as whole to deliver this 1,000 times. Liesbet: Yes, I didn’t say spectrum. I think capacity needs to grow; and it’s a better usage of the spectrum, which can also boost the capacity. Better use of the current spectrum, plus the potential exploration of new spectrum and usage of high frequencies like we see popping up today, will boost capacity. However, then we are probably going into what other technologies we need, rather than just asking what is needed for the new technologies. The MWC roundtable with Alan Carlton of InterDigital (left), Liesbet Van der Perre from IMEC (center), Rui Aguiar from the 5GPPP (right). Alan: Absolutely, and I would just add my two cents in terms of how we see the major driving requirements for 5G. It's really two major things. One is that the driving requirement of ultra-broadband, gigabit per second communications technology is the classic wireless roadmap of give me more, give me more now. And it's still not enough. Then there is the proverbial 50 billion Internet of Things devices; the whole body of new requirements, which didn’t need to be addressed by a mainstream wireless technology in the past. Alan: Moving on to the next question. What do you feel 5G is going to give us that 4G cannot? Liesbet: Today we can anticipate that 4G will not even be able to offer us the capacity that will be needed when the number of devices keeps increasing as it does currently. Even maintaining the service that we have today - with the increasing number of devices – will need more than 4G. Next to that, of course, we hope that there's going to be the opportunity to connect more things and people, and deliver higher services. Rui: I want to take a very common example and a very simple example. We are talking about machines, and we are not really paying attention to what that means. What that means may be that your heart controller is instantly connected to your physician in your town. 5G will give us the trust to actually believe that when we will need to send an emergency signal, we can rely on it because in some way, the emergency signal will reach your physician. I don't really believe that with 4G - at least I would hesitate putting the health of my heart in the capabilities 4G technology. Liesbet: Do you really think trusted networks are going to be extremely important? Rui: Trustable, reliable - of course. We can look at the high bit rate, which may exist. We even look at the virtual reality or something, which I prefer better, the augmented reality scenarios. I really believe it's not just the simple matter of spectrum and capacity. Liesbet: Yeah, of course. In order to be able to make sure your call always gets in, there will be a need to make sure that the capacity is there. In case there is an emergency and many people try to do the same thing; at least the network can support that. 5G needs to support all of that. Alan: I'd very much like to hear your opinion on what you're raising as challenges, like supporting technologies and augmented reality. I think that sort of technology is almost an embodiment of the type of service we'll see emerging in the 5G timeframe in a more mainstream sense. One of the requirements that has been identified in the 5G Public Partnership Project is the one millisecond latency requirement, which I think will be an amazing driver for a new radio system and a new technology, and an entire impact across the system and network and [the radio]. Think back through 2G, through 3G and 4G. There's been a gradual slow roll roadmap, where basically 2G was about voice, where all we needed was 100 milliseconds. 3G and 4G was about video support, which is about 10 to 20 milliseconds, which is a tolerable delay. When we start moving into the 5G timeframe, where we're really interacting as much with objects and devices, that one millisecond latency is going to be a very key requirement. Rui: As you know, I am involved on the steering board of the 5G PPP Association. I have to agree with you. The latency requirement is frightening because what we are talking about is having a multi-access network, multi-service network with latency performance metrics, which are equivalent as a dedicated system. I'm not sure if we'll be able to get much better than these kinds of requirements that we are putting to the latency. To be honest, I think it's a huge challenge that we will have in the upcoming years. Alan: What are the key technologies that you are seeing today that might be part of 5G? Rui: There are two dimensions to the challenge of 5G. One dimension is technology itself. Here, most people are concerned with the radio access, where we go to higher frequencies, to smaller devices, to smaller cells. The other challenge is from a different nature. And it's simply that we need to have a 5G network we can afford. Let's say - we all know that one of the biggest improvements in spectrum that exists in the last 20 years was simply, smaller cells. Now we are reaching a stage where if you go along that line, the number of cells that we are bringing is going to add a huge amount of challenges to the backbone of the system. Now power consumption and backbone is already becoming a problem and it's going to be an increasing problem in the future. We will have a balance regarding what we can do, and what we are able to pay for. There will be a couple of technologies like vocalization software working; software defined radio; energy aware optimizations; not just delay, but power minimization. There will be a couple of technologies that will appear, that at this moment, we have not yet fully explored. Liesbet: We've been working on some of this, and it's definitely not to the point where this research has ended. Commenting on the radio access, I do think next to the smaller cells, there are a couple of disruptive ideas, like for example massive MIMO systems. It looks to be very promising, in order to be able to reduce power consumption and boost the capacity using the current frequencies. Next to that, further deployment of millimeter waves beyond where we are looking today, in the backbone, but potentially also more into the access network, might be a solution because clearly there is a lot of bandwidth available. It might help to cope with the requirements we have there. Alan: Thank you, Liesbet. I agree with both of you. I would add to that, millimeter waves are certainly a critical technology. The move to small cell technology has been one that's been going on for many, many years, and millimeter wave hotspots are the natural next step for us. This is the right time for the embracement of spectrum sharing technologies — an area that has been of massive research over many years, but through initiatives like white space and license shared access. Some of the key enabling building blocks are being developed today that will likely be big enablers in the 5G timeframe.