| CPC H04W 56/001 (2013.01) | 22 Claims |
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1. A method of deriving a propagation delay of radio signals transmitted between a first radio network node having a first plurality of antenna elements and a second radio network node having a second plurality of antenna elements, both nodes being 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, the total calibrated delay being based on results of calibration processes that substantially equalize delays through transmitter paths to and including each antenna element, and delays through receiver paths from and including each antenna element, at 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.
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