The breakthrough of autonomous vehicles without powerful wireless communication is hardly conceivable. Vehicle-to-Vehicle (V2V), Vehicle-to-Network (V2N), Vehicle-to-Pedestrian (V2P) or Vehicle-to-Infrastructure (V2I) are well-known dimensions of autonomous vehicle communication. All of this requires an active and particularly powerful technology for wireless data transmission in order to share many data in real-time. One option is the 5th generation of wireless systems, better known as 5G.
Rapid data transfer in real-time is an inevitable requirement when it comes to driverless car technology
Efficient 5G could provide a very high throughput combined with low latency and low energy consumption. Today’s 4G LTE mobile standard is only able to communicate with 300 megabits per second at a peak data rate of 1 Gb/s as defined by the ITU-R. In reality, it is a far cry from this transfer rate. Only a fraction is available when it comes to surfing the Internet on your smartphone. Furthermore, it does not support real-time transmission. For the breakthrough of autonomous vehicles, data rates up to 10 gigabits per second are needed and thus targeted.
Efficient 5G with low energy consumption is required
In the framework of the EU-funded Flex5Gware project, researchers at the Fraunhofer Institute for Applied Solid State Physics IAF in Freiburg aim to improve driverless car technology by widening the bottleneck of wireless data transfer. They try to develop more power amplifiers which are able to free up additional radio frequencies of up to 6 gigahertz for 5G. Today’s 4G LTE is limited to 2.7 gigahertz.
Allegedly, 15 percent of the German’s mobile phone bill is owed to the consumed power for wireless transmission. Each transmitted bit costs power and thus money. About 200 times of the today’s transfer rate are aimed to transfer with 5G. “For the sake of sustainability, the power efficiency of the cellular communication must be increased substantially for 5G“, says Quay. According to Fraunhofer IAF, this will lead to uncomfortable high energy expenditures. A more efficient 5G technology is highly recommended. The main reason for the inefficient data transfer is the pointless transmission of the radio waves into the air. It happens without any idea of the recipient’s location. “Due to its special crystal structure, the same voltages can be applied at even higher frequencies, leading to a better power and efficiency performance“, Quay adds.
Sophisticated new electronically steerable antennas and GaN-based power amplifiers make possible a targeted transmission to the recipient without senseless data transfer in all directions.
“Higher frequencies mean faster data transmission, but unfortunately also less available power for the transmitters“, says Quay. On that score, Fraunhofer IAF produces transistors and microchips with a size of only a few square millimeters in size made of the semiconductor material gallium nitride (GaN). Currently, the scientists are testing prototypes up to frequencies of 6 gigahertz.
GaN has become an affordable material owing to the success of LEDs
“We are at a turning point“, says Dr. Rüdiger Quay of the Fraunhofer Institute for Applied Solid State Physics IAF in Freiburg (Germany). “So far, it is mainly humans who are communicating with each other using mobile communication devices. In the future, cars, devices, or production machines will join the networks.“
The basic materials for GaN are available in large quantities. Nitrogen can be extracted from the air. Gallium is a waste product in metal working. GaN is an essential component of blue and white light-emitting diodes (LEDs) or gallium nitride nanotubes which are applied in optoelectronics and biochemical-sensing applications. Efficient recycling processes for LEDs could free up GaN. Owing to the success of LEDs, GaN has become an affordable material. Today, the power savings during operations exceed the production costs, in comparison to silicon, of the still more expensive GaN.