Abstract: A method of updating spatial filters in a radio network comprising at least two transmit nodes each in radio communication with at least one receive node on a Multiple-Input Multiple-Output (MIMO) radio channel, comprises transmitting, from the respective transmit node, first reference signals precoded by a first spatial filter of the respective transmit node; and receiving, from the receive nodes, second reference signals that are precoded using a second spatial filter of the respective receive node and an error matrix of the respective receive node. The second spatial filter depends on a channel estimate based on the transmitted first reference signals. The error matrix is indicative of an error of the first and second spatial filters in equalizing the MIMO radio channel.

Abstract: A method of updating spatial filters in a radio network comprising at least two transmit nodes each in radio communication with at least one receive node on a Multiple-Input Multiple-Output (MIMO) radio channel, comprises transmitting, from the respective transmit node, first reference signals precoded by a first spatial filter of the respective transmit node; and receiving, from the receive nodes, second reference signals that are precoded using a second spatial filter of the respective receive node and an error matrix of the respective receive node. The second spatial filter depends on a channel estimate based on the transmitted first reference signals. The error matrix is indicative of an error of the first and second spatial filters in equalizing the MIMO radio channel.