Method and apparatus for antenna calibration

A first network device, comprising:

• a processor;
• and
• a memory, the memory containing instructions executable by the processor, whereby the first network device is operative to:
• receive a first radio signal generated by the first network device via a receiver connected to an antenna of the first network device, wherein the first radio signal is a calibration reference signal generated by a transmitter of the first network device for antenna calibration purposes;
• receive at least one second radio signal generated by at least one second network device via the antenna of the first network device;
• and
• determine an impairment related to the antenna of the first network device based on the received first radio signal and the at least one second radio signal,
• wherein there is a line of sight, LOS, path between the antenna of the first network device and an antenna of each of the at least one second network device.