A complexity reduction scheme for interference cancellation radio repeaters

When applying the real time interference cancellation (ICAN) technique to a radio repeater, the most urgent task is to reduce the complexity of an ICAN system in the radio repeater. For complexity reduction, polyphase filters with a folded structure are used to perform downsampling and upsampling, and input and output filtering for spectrum control simultaneously. Frequency translation of the signal to avoid aliasing due to downsampling is efficiently executed by a Hilbert transform. The complexity of the proposed scheme is roughly one-fourth that of the conventional scheme with negligible deterioration of the signal quality and the power spectrum of the ICAN system.