Method and radio node for controlling change of communication mode

1. A method for controlling a change of communication mode between transmit mode and receive mode in a radio node according to a Time Division Duplex, TDD, scheme, the radio node having at least two parallel branches and antennas for transmission and reception of radio signals through each respective one of the at least two parallel branches, wherein the branches currently operate in a first communication mode of said transmit mode and receive mode, the method comprising:

obtaining one or more indication signals generated by one or more of the at least two parallel branches to indicate that said first communication mode has been turned off,

determining whether said first communication mode has been turned off in all of the at least two parallel branches based on the obtained one or more indication signals, and

instructing the at least two parallel branches to operate in a second communication mode,

wherein when it is determined that said first communication mode has not been turned off in a faulty branch of said at least two parallel branches, the method also comprises at least one of:

disabling the first communication mode in the faulty branch, and

reporting said faulty branch to a supervision centre.

2. A method according to claim 1 , wherein said determination is made when a time-out is reached for the first communication mode.

3. A method according to claim 1 , further comprising adjusting a transmission delay of the faulty branch.

4. A method according to claim 3 , wherein adjusting the transmission delay comprises altering a transmit delay buffer coupled to the faulty branch.

5. A method according to claim 1 , wherein the first communication mode is transmit mode and the second communication mode is receive mode, said indication signal being triggered in a respective branch of the at least two parallel branches by any of:

a transmit chain in the respective branch has no input signal,

the transmit chain in the respective branch is shut off,

a transmit power amplifier in the respective branch is shut off, and

signals leaving the transmit chain in the respective branch have a strength not exceeding a maximum acceptable level.

6. A method according to claim 1 , wherein the first communication mode is receive mode and the second communication mode is transmit mode, said indication signal being triggered in a respective branch of the at least two parallel branches when a receive chain in the respective branch is shut off.

7. A method according to claim 1 , wherein the method is performed at intervals according to a scheme, to check whether the at least two parallel branches are aligned or misaligned in time.

8. A method according to claim 1 , wherein the method is performed in order to identify any faulty branch when detecting disturbances, damage or interference, either caused by the radio node.

9. A method according to claim 1 , wherein the radio node is a base station of a cellular network, or a user equipment.

10. A radio node configured to control a change of communication mode between transmit mode and receive mode according to a Time Division Duplex scheme, the radio node comprising:

at least two parallel branches and antennas for transmission and reception of radio signals through each respective one of the at least two parallel branches, wherein the branches are operable in first and second communication modes of said transmit mode and receive mode, and

a control unit comprising:

an obtaining unit adapted to obtain one or more indication signals generated by one or more of the at least two parallel branches to indicate that said first communication mode has been turned off,

a logic unit adapted to determine whether said first communication mode has been turned off in all of the at least two parallel branches based on the obtained one or more indication signals, and

an instructing unit adapted to instruct the at least two parallel branches to operate in the second communication mode,

wherein when it is determined that said first communication mode has not been turned off in a faulty branch of said at least two parallel branches, the logic unit is further adapted to perform at least one of:

disable the first communication mode in the faulty branch, and

report the faulty branch to a supervision centre.

11. A radio node according to claim 10 , wherein the logic unit is further adapted to make said determination when a time-out is reached for the first communication mode.

12. A radio node according to claim 10 , wherein the control unit is further adapted to adjust a transmission delay of the faulty branch.

13. A radio node according to claim 12 , wherein the control unit is further adapted to adjust the transmission delay by altering a transmit delay buffer coupled to the faulty branch.

14. A radio node according to claim 10 , wherein the first communication mode is transmit mode and the second communication mode is receive mode, and the at least two parallel branches are configured to trigger said indication signal by any of:

a transmit chain in the respective branch has no input signal,

the transmit chain in the respective branch is shut off,

a transmit power amplifier in the respective branch is shut off, and

signals leaving the transmit chain in the respective branch have a strength not exceeding a maximum acceptable level.

15. A radio node according to claim 10 , wherein the first communication mode is receive mode and the second communication mode is transmit mode, and the at least two parallel branches are configured to trigger said indication signal when a receive chain in the respective branch is shut off.

16. A radio node according to claim 10 , wherein the radio node is configured to control said change of communication mode at intervals according to a scheme, to check whether the at least two parallel branches are aligned or misaligned in time.

17. A radio node according to claim 10 , wherein the radio node ( 700 ) is configured to control said change of communication mode in order to identify any faulty branch when detecting disturbances, damage or interference, either caused by the radio node.

18. A radio node according to claim 1 , wherein the radio node is a base station of a cellular network, or a user equipment.