Patent ID: 9059772
Filing Date: 2015-06-16
Classification: H04B

Abstract:
1. A method for self-interference suppression in a multi-antenna device that is part of a communication channel between a transmitter and a receiver of a wireless communication system the multi-antenna device being located between the transmitter and the receiver and using antennas and a relay unit for forwarding signals from the transmitter to the receiver, the communication channel having a transmit channel, defined by a transmit channel matrix between the transmitter and the multi-antenna device, a receive channel defined by a receive channel matrix, between the multi-antenna device and the receiver, and a self-interference channel between an output and an input side of the multi-antenna device, the self-interference channel being defined by a self-interference channel matrix, the method comprising: equipping the multi-antenna device with at least four antennas of which at least two antennas are input antennas ( suppressing the self-interference channel by using two filtering matrix arrangements, (i) a receive filtering matrix arrangement being inserted between the input antennas and the relay unit and (ii) a transmit filtering matrix arrangement being inserted between the output antennas and the relay unit, wherein the receive filtering matrix arrangement is defined by a receive filtering matrix W the transmit filtering matrix arrangement is defined by a transmit filtering matrix W said transmit and said receive filtering arrangements cancel at least one eigenmode of the self-interference channel, by choosing columns of the transmit and the receive filtering matrices to be orthogonal to said at least one eigenmode of the self-interference channel that is to be cancelled, the self-interference suppression by cancelling said at least one eigenmode is made with the transmit and the receive filtering matrix arrangements meeting a selection criterion for minimizing risk of loss of one or several dominating eigenmodes of one or both of the transmit channel and the receive channel.