From coffee-shop customers who connect their laptop to the local Wi-Fi network to distant weather monitoring stations within the Antarctic, wireless communication is a vital part of contemporary life. Researchers worldwide are currently working on the following evolution of communication networks, called “beyond 5G” or 6G networks. To enable the near-instantaneous communication needed for applications like augmented reality or the handheld remote control of surgical robots, ultra-high data speeds shall be needed on wireless channels. In a study published recently in IEICE Electronics Express, researchers from Osaka University and IMRA AMERICA have found a method to increase these data speeds by reducing the noise within the system through lasers.
To pack in large amounts of knowledge and keep responses fast, the sub-terahertz band, which extends from 100 GHz to 300 GHz, shall be utilized by 6G transmitters and receivers. A classy approach called “multi-level signal modulation” is used to further increase the info transmission rate of those wireless links. Nonetheless, when operating at the highest end of those extremely high frequencies, multi-level signal modulation becomes highly sensitive to noise. To work well, it relies on precise reference signals, and when these signals begin to shift forward and backward in time (a phenomenon called “phase noise”), the performance of multi-level signal modulation drops.
“This problem has limited 300-GHz communications to this point,” says Keisuke Maekawa, lead writer of the study. “Nonetheless, we found that at high frequencies, a signal generator based on a photonic device had much less phase noise than a traditional electrical signal generator.”
Specifically, the team used a stimulated Brillouin scattering laser, which employs interactions between sound and lightweight waves, to generate a precise signal. They then arrange a 300 GHz-band wireless communication system that employs the laser-based signal generator in each the transmitter and receiver. The system also used on-line digital signal processing (DSP) to demodulate the signals within the receiver and increase the info rate.
“Our team achieved a single-channel transmission rate of 240 gigabits per second,” says Tadao Nagatsuma, PI of the project. “That is the very best transmission rate obtained to this point on the planet using on-line DSP.”
As 5G spreads across the globe, researchers are working hard to develop the technology that shall be needed for 6G, and the outcomes of this study are a big step toward 300GHz-band wireless communication. The researchers anticipate that with multiplexing techniques (where multiple channel might be used) and more sensitive receivers, the info rate might be increased to 1 terabit per second, ushering in a brand new era of near-instantaneous global communication.
