The promise of 6G It has been on the table for years, but there is a part of that story that is usually left out of the window. We’re not just talking about faster mobile phones, seamless video calls or almost instant downloads, but about something much more complex: getting huge amounts of data to travel through the air with great stability. That’s where technology meets its own ceiling. And a Japanese team just placed a tiny piece right in the center of that problem.
112Gbps. What the researchers have achieved is to send data wirelessly at 112 Gbps in the 560 GHz band. The demonstration was announced by Tokushima University and researchers from this university and Gifu University participated. The important fact is not only the speed, which is already enormous, but also the place where it has been achieved: above 420 GHz. According to the researchers, it is the first time that 100 Gbps class wireless communication has been demonstrated above 420 GHz.
The 350 GHz wall. To understand why this result matters, we have to look at the problem that terahertz communications have been experiencing. Mobile networks have gained speed and capacity by increasing working frequencies, but this path becomes more complicated when entering extreme territories. Above 350 GHz, conventional electronic technologies face to lower output power and increased phase noise. In other words: it costs more to generate a strong, stable and useful signal to transmit data at high speed.
The tiny piece is a microcomb. The word may sound strange, but the underlying idea is quite visual. A microcomb generates multiple regularly spaced optical frequency modes, like the tines of a comb. Tokushima University explains that this allows very high frequency optoelectronic signals to be obtained with a quality superior to that of conventional electronic approaches. In the configuration used by the team, an optical fiber is attached directly to the microresonator, which eliminates the need to perform extremely precise optical alignments as in conventional systems.
The way forward. First, the microcomb allows the generation of a cleaner and more stable terahertz signal than that obtained with conventional electronics at those frequencies. Then modulation comes into play, which is the way of encoding the information within that signal so that it carries more data. The official source talks about high-order modulation techniques, such as QPSK and 16QAM. With QPSK, the system achieved 84 Gbps; with 16QAM, it reached 112 Gbps.
It is not for tomorrow’s mobile. It is advisable to understand the scope of the advance before imagining phones directly connected to 560 GHz. The university itself speaks of a technological base for ultra-fast backhaul links and integrated photonic-wireless networks in 6G systems. Simply put, backhaul is the part of the infrastructure that connects base stations to the main network. That’s where very high-capacity wireless transmission can make sense: moving large volumes of data between fixed points.
There is still a way to go. Researchers want to extract even more performance from these waves by reducing phase noise, developing more advanced antennas and increasing power output. The objective is clear: that speeds like these do not remain a one-time demonstration, but can be sustained at greater distances. There will be an important part of the reality test. What we’ve seen now is not a finished 6G network, but rather a piece of technology that helps show how a part of that network can be built.
Images | Tokushima University
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