Over the Air Antenna Synchronization in Wireless Communication Network

A method of deriving a propagation delay of radio signals transmitted between a first radio network node and a second radio network node operative in a wireless communication system, comprising:

• obtaining a total calibrated delay equal to the sum of a calibrated receiver delay and a calibrated transmitter delay, for each of the first and second radio network nodes;
• transmitting, from the first radio network node to the second radio network node, a first signal and saving a first timestamp indicating the time of transmission of the first signal;
• receiving, at the first radio network node from the second radio network node, a second signal including a processing delay of the second radio network node, and saving a second timestamp indicating the time of reception of the second signal;
• and
• deriving a propagation delay between the first and second radio network nodes based on the difference between the first and second timestamps and the obtained delays.

A first radio network node operative in a wireless communication system and operative to derive a propagation delay of radio signals transmitted between the first node and a second radio network node operative in the wireless communication system, comprising:

• at least three antennas;
• receiver circuitry connected to the antennas and having a receiver path delay;
• transmitter circuitry connected to the antennas and having a transmitter path delay;
• processing circuitry operatively connected to the receiver and transmitter circuitry, the processing circuitry configured to:
• obtain a total calibrated delay equal to the sum of a calibrated receiver delay and a calibrated transmitter delay, for each of the first and second radio network nodes;
• transmit, from the first radio network node to the second radio network node, a first signal and save a first timestamp indicating the time of transmission of the first signal;
• receive, at the first radio network node from the second radio network node, a second signal including a processing delay of the second radio network node, and save a second timestamp indicating the time of reception of the second signal;
• and
• derive a propagation delay between the first and second radio network nodes based on the difference between the first and second timestamps and the obtained delays.