US Patent 7747250 Calibration method to achieve reciprocity of bidirectional communication channels

The present invention relates to a method and arrangement to enhance the communication performance in wireless communication systems. The method of the invention provides a method of calibrating at least one first radio node in a wireless communication network. The communication network comprises at least a first radio node and a second radio node, which can be arranged to be in radio communication with each other. The calibration method is based on that at least one representation of radio channel characteristics, which has been exchanged from one radio node to the other. Whereby inaccuracies and differences in transmit receive chains are compensated and channel reciprocity can be used.