UC Irvine

One of the main challenges of In-Band Full-Duplex (IBFD) communication systems is the mitigation of Self-Interference (SI). Most popular self-interference suppression techniques involve taking a copy of the transmitted signal and scaling the copy before subtracting it at the receiver to get the desired signal minus the interference. The scaling involves rotating the phase of the copy and modifying its amplitude. However, due to channel variations, the replica of the transmitted signal could be delayed.

Most systems work with the underlying assumption that the baseband signal remains constant over a delay time interval. It is commonly assumed that baseband information signal experiences an insignificant amount of delay. This does not hold true as the modulated bandwidth increases. If this delay effect is taken into consideration when designing the canceller, the canceller’s performance can be improved.

This thesis work analyzes the effects of the baseband signal delay in Single Channel Full Duplex SI Cancellation Systems. The analysis also attempts to investigate the relationship between signal bandwidth on the cancellation capabilities of the system. For this, an RF Cancellation (RFC) block was designed at the Wireless Systems and Circuits Laboratory to be added as a peripheral to the Single Channel RF System. This document details the results of controlled delay experiments conducted on the RF Cancellation Block.