A frequency domain approach for complexity reduction in wideband radio interference cancellation repeaters

To cancel wideband feedback interference signals that enter the receive antenna via near-by reflectors from the transmit antenna of the radio repeater, the wideband input signal is first split into several narrowband signals by narrowband filters. Interference cancellation (ICAN) is then performed on each split narrowband signal separately. As a result, the major portion of the complexity of a feedback ICAN system in a wideband radio repeater is accounted for by input and output filtering for spectrum control instead of the complexity of the ICAN algorithm itself. In this work, to reduce the overall complexity of the feedback ICAN system, a frequency sampling filter that is efficiently designed in the frequency domain when the filterpsilas frequency response has a narrow bandwidth is applied to input and output filtering for spectrum control. The proposed filtering method reduces the complexity of the feedback ICAN system to less than a half that of the conventional system with no performance deterioration.