The 5G wireless network is not yet deployed, but ECE researchers are already working on what comes next—6G.

According to Walid Saad, ECE associate professor, the movement from 2G to 5G has been driven by one consideration: the need for higher data rates. The next generation, however, will have to serve technologies with diverse needs—from autonomous vehicles to virtual reality.

These new technologies will require more than just high data rates, explains Saad, who was recently named IEEE Fellow for his contributions to distributed optimization in cooperative and heterogeneous wireless systems. “We still need high data rates, but we will also need reliable and low latency communication. We need reliability of 99.99999 percent or even more.” 5G, he continues, should be able to deliver that reliability to static nodes and simple scenarios, but “we need to start thinking about what is next—autonomous vehicles, drones, and virtual reality.”

Autonomous vehicle communication

Because of the safety considerations of autonomous vehicles, poor communication will have a greater impact than just a dropped call. “A car needs to control its speed and distance, gather data from various sensors, and exchange maps and information with other vehicles and nodes,” says Saad. 

Computation is also an issue. Computation for these systems is frequently done in the cloud, where there are more computer resources. With a strong communications system, however, computation could be distributed between many different vehicles or nodes. According to Saad, this means that joint design of communications, computing, and control is necessary for 6G.

In addition to these demands, moving nodes like vehicles pose particular challenges for current wireless technology. Millimeter wave technology, for example, allows for high-data rate communications, but is highly susceptible to blocking, explains Saad. If anything gets between the vehicle and a millimeter wave base station, communications are interrupted and become unreliable.

Drone communication

And then there are drones. “Now, we have antennas tilted downwards, and drones are served by the back lobe of antennas that are optimized for communication on the ground,” says Saad. “We talk about areal spectral efficiency, a very common metric, but now we need to talk about volumetric spectral efficiency. 6G will be a three-dimensional system.” All of these considerations need to be taken into account before the launch of 6G, because these are the technologies that will be incorporated.

Virtual reality communication

Applications like virtual reality and brain-computer interactions also pose unique challenges. “Virtual reality requires a lot of human interaction,” says Saad. “You are moving around, moving your head, and your communications system should be able to maintain your experience in the virtual environment.” This is another application that isn’t just about data rates—it also requires a balance between efficiency and acceptable performance quality.

“We have shown that a brain does not discern between 1 ms and 2 ms,” explains Saad. “We need to figure out the impact of brain perception on quality of service. If the user can’t see the difference, the communications can stay at 2 ms and save power.”

Enabling technologies of 6G

Enabling 6G is not just a matter of optimizing the physical layout and design of wireless nodes—the network itself needs to adjust. And the answer, according to Saad, might be in artificial intelligence (AI). “All of these applications together call for an AI-enabled wireless network. AI can enable 6G networks to not only learn, but to also think and self-sustain while using machine learning to adapt to the needs of different applications and environments.” Saad envisions a 6G system where man-made structures (such as walls and buildings) can become active wireless transmitters. “Equipped with AI, they could provide truly pervasive communications while challenging the conventional antenna-mobile device paradigm.”

These new technologies also come with new security concerns, and Saad and his team are trying to address those while the systems are being designed. Like most of his projects, Saad’s security research involves the intersection between multiple fields. “There are two aspects to these attacks,” says Saad. “Reliable communication and control systems that are not only robust against attacks, but can also adapt to faulty data.” Saad notes that there are three aspects to security for autonomous systems: communication, control system, and artificial intelligence. “An attacker might attack just one, but all three need to be robust to an attack.”

Because there will be applications in every field that use 6G networks, wireless researchers must reach into those fields to jointly design systems that work. 

 

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