Researchers Develop a Self-Interference Cancellation Filter for Next-Gen Wireless Communication Technology

May 10, 2020 by Luke James

The filter, developed by researchers at Toyohashi University of Technology (TUT), realizes in-band full-duplex by using the same frequency to simultaneously transmit and receive wireless communications.

In wireless communication, in-band full duplex—where the same frequency is used to simultaneously transmit and receive—is a difficult task that even the latest wireless communication standard, 5G, does not realize. 


Eliminating RF Self-Interference

According to the TUT team’s research, their self-interference cancellation filter is able to estimate distortion caused by radio and the distortion of the radio channel with high accuracy, enabling it to cancel self-interference.

In addition to this, it is said to be able to quickly reach the solution of the filter with low computational complexity. Currently, it is necessary to divide the time when transmitting and receiving at the same frequency or to divide the frequency when simultaneously transmitting and receiving. 


In-band full-duplex transceiver.

Diagrams of in-band full-duplex transceiver (top), circuit block model of transceiver (middle), mathematical model using five operators (bottom). Image credited to Toyohashi University of Technology


Achieving High Precision, Speed, and Low Computational Complexity

To improve on current filters that require high computational complexity to remove self-interference with high precision, the research team worked on developing a filter that simultaneously satisfies the conditions of high precision, high speed, and low computational complexity.

This has reportedly been achieved by breaking down the problem of self-interference into five smaller problems and expressed each using mathematical operators. Doing this, the team was able to clarify that the solution method for each of these five problems and the solution method for the larger overarching problem could be derived using five operators and their inverse operators.

Applying this solution to a filter, the team was reportedly able to cancel self-interference with higher precision and speed and lower computational complexity than ever before.


Applications in Next-Gen Wireless Technologies 

The TUT research team has high hopes for their filter and say that they expect it to be applied to the next generation of wireless communication technology because it “increases the feasibility of in-band full-duplex communications in small and inexpensive radios such as smartphones.”