Korean researchers demonstrated the 'full duplex radio' technology, one of the core 5G mobile communication technologies, for the first time in the world. Korea laid the foundation for leading the standardization of next-generation mobile communication and the commercialization of related technologies.

The full duplex radio technology doubles the frequency efficiency and speed as it sends and receives signals in the same frequency band and the same time slot. As it can take advantage of existing frequencies twice as much, its economic value is equal to a few trillion Korean Won.

Prof. Chae Chan-byeong, School of Integrated Technology, Yonsei University, and his research team announced on January 11 that they demonstrated the full duplex radio technology at GLOBECOM, a communications conference held by the Institute of Electrical and Electronics Engineers (IEEE) last month in Austin, Texas, US. Several research institutes have conducted tests since 2010, but never implemented and demonstrated a prototype at an open international conference in real time.

The full duplex radio technology is regarded as one of the core 5G technologies along with the massive MIMO that increases the speed with tens of antennas. The key is to send and receive signals in the same frequency band at the same time. It is a concept more advanced than LTE-TDD, the time division method.

In general, communication signals use upstream and downstream separately to prevent interference. In contrast, LTE-TDD divides time in the same frequency to process upload and download. For instance, 0.5 seconds are used for upload and 0.5 seconds for download. The full duplex radio technology goes a step further, and processes upload and download in the same frequency band at the same time without dividing the time.

As interference is removed technologically, the time required separately for upload and download can be used concurrently for upload and download respectively. This is why LTE-TDD is called the half duplex radio as compared to the full duplex radio.

If the full duplex radio technology is commercialized, it will be possible to process upload and download at the same time with the 10㎒ bandwidth. It means that frequency efficiency will be doubled. Considering the cost of frequency auction worth a few trillion Korean Won, that much money can be saved. It will be a great economic boon.

As the speed is doubled, we can get a step closer to 5G. If the massive MIMO increased the speed 10 times, the full duplex radio technology will increase the speed 20 times. In the 2010's, leading research institutes, including Stanford, Princeton and Rice University, began to research the full duplex radio technology in earnest for this reason.

Prof. Chae and his research team made the prototype based on the LTE Release 8, one of the LTE standards, and the National Instrument (NI) solution. It is said that great scholars as well as Ed Tiedemann, senior vice president of Qualcomm visited the booth and showed such great interest that they engaged in technical discussions.

“Last July, we joined NI's lead user program for the first time in Asia and succeeded in demonstrating the full duplex radio technology, which has been discussed only theoretically,” said Prof. Chae. “We will make efforts to enable Korea to contribute to standardizing 5G and commercializing it first.”

Since he came to Yonsei University in March 2011, Prof. Chae has conducted various projects, such as the IT manpower training project and the IITP project supervised by the Ministry of Science, ICT & Future Planning, and prototyping researches, and produced the first result after 3 years' hard work. ♦