A transceiver (100) is disclosed for a communication node adapted to transmit a first signal to an other communication node and to receive a second signal from the other communication node. The transceiver comprises at least one antenna (110), at least one transmitter module (120), at least one receiver module (130), and a mode alternator (160). The at least one antenna is adapted to simultaneously transmit the first signal and receive the second signal, wherein the first and second signals have equal carrier frequencies and different polarizations. The second signal is for determining a channel characterization of a communication channel over which the second signal is received, and the channel characterization is for determination of one or more transmission parameters for the first signal. The mode alternator is adapted to alternate a mode of operation of the transceiver between at least a first and a second mode of operation. The first mode of operation comprises the transceiver transmitting the first signal using a first polarization and receiving the second signal using a second polarization, and the second mode of operation comprises the transceiver transmitting the first signal using a third polarization and receiving the second signal using a fourth polarization. Corresponding communication node, communication system, method and computer program product are also disclosed.