A scheme to compensate for the input multipath channel effect in an interference cancellation repeater for mobile communication systems

Conventional interference cancellation (ICAN) techniques are mainly used to prevent feedback oscillation of a radio repeater when the repeater’s gain is larger than the isolation between the transmit and receive antennas of the repeater. Therefore, the output signal distortion of the radio repeater, which is caused by the multipath channel between the repeater’s input antenna and a base station, is not properly compensated. In this paper, a scheme to compensate for the output signal distortion in conventional ICAN repeaters is proposed. The compensation is performed by estimating the input multipath channel, inverting the estimated channel, and compensating the input signal using the inverted channel prior to feedback signal cancellation. The validity of the proposed scheme is confirmed by showing that the output signal quality of a conventional ICAN repeater is considerably improved by this scheme.