Towards 6G: How could the future wireless networks look like?
By: Eurecom Communication
Tags: Erc, AI, Wireless, Drones, 6g

Nowadays, wireless networks are mainly configured in a centralised manner, where the whole traffic is managed from a central point. In fact, a central unit collects and processes all the information, in order to make decisions on resource allocation, a process often introducing extra delays. However, in the future we can imagine having billion devices from phones and tablets to industrial machines and drones, struggling to use the spectrum, causing a lot of interference, but also demanding instantaneous decisions, especially in the case of critical applications. Naturally, we can wonder, could we exploit part of the capabilities of such devices at the edge of the network by deploying a network in a distributed way, instead of relying on a centralised one?

Dr. David Gesbert, professor, head of the Communications Systems Department of EURECOM and holder of the ERC Advanced grant PERFUME on Smart Device Communication, will guide us through the main outcomes of PERFUME project: an emerging distributed network design, featuring intelligence and decision making at the edge nodes.

Q. What is the context and motivation of your recently finished 5-year ERC Advanced project, PERFUME?

DG. Our goal was to design how future wireless networks will operate, going towards the future 6G (beyond5G) technology, making use of all the capabilities of the network closer to the end user. In other words, exploit the memory, the computing power and transmission capabilities of phones, tablets, PCs but also robots, which are all equipment residing at the edge of the network. Currently, the terminal equipment is viewed as passive devices, running applications in a way that does not require local intelligence, under-utilising their potential capabilities. Also, in the future the rapid increase of automated industrial manufacturing, using robotic devices to perform essential tasks, will rapidly increase the need for timely decisions locally, which are extremely hard to achieve in a centralised deployment. Indeed, those devices have computational power used currently to run their applications, but not yet for the benefit of the network. So the idea is, why don’t we use the network in a distributed fashion and exploit part of the devices capabilities for the service of the network, instead of relying on a centralised network, where we need a unit that controls all traffic?

Q. What is the difference between a centralised and a distributed network?

DG. In a centralised network, the central point would have indeed all the information needed to make a good informed decision on how the resources would be allocated to the devices of the network (power transmission, frequency, bandwidth), but it will take much time to collect it. So, by the time the decision is sent back to the user, it could be already outdated, since networks are not static. For example, imagine you are in your car, moving around, with an environment changing constantly, therefore if you take too much time to make a decision, there would be too much latency, causing potential safety issues.

On the other hand, in a distributed network the decisions could be very quick, since there is no need to centralise everything. The downside however, is the access to information. In fact, each terminal typically only has access to its local neighbourhood information, “seeing” maybe a few other devices, without knowing exactly what the other devices are going to do. So, they are going to try and cooperate based on partial information. If I have to give an analogy, imagine you are playing football with a team and you need to score a goal, but suppose that the players are playing blind folded and they don’t actually see each other: they have to operate with hearing and feeling but not seeing. Now, they have to progress to the opposite side of the field, pass the ball to each other and score the goal. Well, it is not easy to cooperate when you don’t know what your teammates around are doing! The same problem applies here. For instance radio devices would like to cooperate with each other to minimise interference, but they have limited inter-communication capability between them, hence how can they coordinate under such uncertainties?

Q. Could a distributed network configuration improve the network performance then?

DG. In fact, between the two network configurations we end up with a trade off: more timely decisions but based on partial information (distributed) versus more complete information but decisions with more delay (centralised). In other words, either we centralise all the information for all the devices, push them to the cloud to make a decision and send it back to the network, or we maintain the decisions at the local level. For a critical mission, needing an immediate response as accurate as possible, can we know which is the best design between the two?

Well, there is no easy answer! For that, there is a need for extensive analysis, but we were able to show that distributed systems would do just as well and even better than the centralised ones. Then, the choice depends on the exact application.