Method and active antenna system in telecommunication networks

1. A method for calibrating an active antenna system comprising a radio unit and an antenna array, wherein the radio unit comprises a plurality of transceiver branches and a calibration branch, the method comprising:

calibrating at least one, but less then all, out of the plurality of transceiver branches as reference branch or branches;

determining whether the radio unit and the antenna array are properly connected by sending a test signal between the calibration branch and the reference branch or branches;

in response to determining that the antenna array and the radio unit are properly connected, calibrating non-calibrated transceiver branch or branches out of the plurality of transceiver branches.

2. The method according to claim 1 , further comprising:

saving information regarding properties of the radio unit obtained during calibrating of the reference branch or branches;

and wherein the determining whether the radio unit and the antenna array are properly connected is also based on the saved information regarding properties of the radio unit.

3. The method according to claim 2 , wherein the information regarding properties of the radio unit relates to one or more of the following quantities: variable gain amplifier (VGA) linearity of a receiver in each reference branch, gain of the receiver in each reference branch, frequency response of the receiver in each reference branch, parameters regarding one or more of amplitude, time, and phase of an automatic gain control (AGC), VGA linearity of a transmitter in each reference branch, gain of the transmitter in each reference branch, frequency response of the transmitter in each reference branch, gain of a transmitter observing receiver (TOR) in each reference branch, and the frequency response of the TOR in each reference branch.

4. The method according to claim 1 , wherein the calibrating each reference branch is performed while the antenna array and the radio unit are not connected.

5. A method for onsite automatic maintenance of an active antenna system comprising a radio unit and an antenna array, wherein the radio unit comprises a plurality of transceiver branches, the method comprising:

performing a self-test of the active antenna system;

determining whether the active antenna system deviates from normal operation based on the self-test;

in response to determining that the active antenna system deviates from normal operation, determining whether a recalibration of the active antenna system can bring the active antenna system back to normal operation; and

in response to determining that the recalibration of the active antenna system can bring the active antenna system back to normal operation, calibrating the active antenna system by:

calibrating at least one, but less then all, out of the plurality of transceiver branches as reference branch or branches; and

while the antenna array and the radio unit are connected, calibrating non-calibrated transceiver branch or branches out of the plurality of transceiver branches.

6. The method according to claim 5 , further comprising:

in response to determining that a recalibration of the active antenna system cannot bring the active antenna system back to normal operation, closing at least one transceiver branch of the active antenna system.

7. An active antenna system comprising:

an antenna array; and

a radio unit comprising a plurality of transceiver branches, wherein the active antenna system being configured to perform onsite automatic maintenance by performing operations to:

perform a self-test of the active antenna system;

determine whether the active antenna system deviates from normal operation based on the self-test;

in response to a determination that the active antenna system deviates from normal operation, determine whether a recalibration of the active antenna system can bring the active antenna system back to normal operation; and

in response to a determination that the recalibration of the active antenna system can bring the active antenna system back to normal operation, calibrate the active antenna array system by performing operations to:

calibrate at least one, but less then all, out of the plurality of transceiver branches as reference branch or branches; and

while the antenna array and the radio unit are connected, calibrate non-calibrated transceiver branch or branches out of the plurality of transceiver branches.

8. The active antenna system according to claim 7 , further comprising:

in response to a determination that the recalibration of the active antenna system cannot bring the active antenna system back to normal operation, closing at least one transceiver branch of the active antenna system.