Currently, there are two main standards for 5G networks—mmWave and Sub-6GHz. The former focuses on speed, while the latter focuses on coverage. Engineers at the University of California, San Diego, have found a way to use algorithms to project faster signals around obstacles, thus combining the advantages of both standards.
Sub-6GHz primarily uses frequencies below 6GHz, allowing it to penetrate obstacles and provide indoor coverage, but its speed isn't significantly faster than 4G. mmWave, on the other hand, transmits at very high frequencies, enabling the transmission of large amounts of data at once, but it cannot be transmitted from very far away or through walls.
In this new study, researchers at the University of California, San Diego, set out to find a way to combine mmWave and Sub-6GHz coverage. Typically, millimeter-wave signals are transmitted as a focused beam of laser light between a base station and a receiver (such as a user's mobile phone). However, of course, if this beam of light is interrupted, such as by a person, object, or wall, the signal is lost.
Therefore, the team decided to try splitting a single beam into several beams and having them take different paths to reach the receiver. A new set of specialized algorithms tells the base station to do this, causing some beams to go directly to the receiver, while others are guided to bounce off surfaces such as glass, metal, concrete, or drywall to reach the device. These algorithms can learn the optimal path and optimize the angle, phase, and power of each beam to improve the signal.
"You would think that splitting the beam would reduce the signal throughput or quality," said Dinesh Bharadia, senior author of the study. "However, the way we designed our algorithm, mathematically speaking, gives you higher throughput while transmitting the same total power as a single-beam system."
Researchers tested the system, which they call mmReliable, both indoors and outdoors in an office building. In indoor tests, mmReliable was able to continuously transmit high-speed connections of 800 Mbps to mobile phones without dropping the connection, even when users moved behind desks, walls, and other obstacles. Outdoors, the system provided a connection up to 80 meters (262.5 feet). The team says the system can be scaled to existing 5G infrastructure because it requires no new hardware. Other experiments have explored ways to boost 5G speeds by tapping into existing 4G frequencies.
