Interference-protected control message transmission in a mobile communications network

1. A method of protecting transmission of a control message, in a mobile communications network, between a first access node and a user equipment, the method comprising:

in response to a need for transmitting the control message, transmitting, between the first access node and a second access node, an indication of at least one protected time-slot for transmitting the control message; the transmitting of the indication prompting reduction of spectral interference caused by the second access node during the at least one protected time-slot;

wherein the transmitting of the indication of the at least one protected time-slot is part of negotiating of the at least one protected time-slot between the first access node and the second access node, the negotiating including:

sending, from the first access node to the second access node, a request message indicating a plurality of candidate time-slots from which the at least one protected time-slot is selected; and

receiving, from the second access node, an acknowledgement message positively and/or negatively acknowledging candidate time-slots from which the at least one protected time-slot is selected.

2. The method of claim 1 :

wherein the control message is a handover command commanding the user equipment to execute a handover from the first access node to a different access node;

further comprising transmitting the handover command from the first access node to the user equipment.

3. The method of claim 2 , wherein the different access node is the second access node.

4. The method of claim 1 , wherein the indication of the at least one protected time-slot is transmitted as part of a handover request message.

5. The method of claim 1 , wherein the indication of the at least one protected time-slot is transmitted as part of a handover request reply message.

6. The method of claim 1 , further comprising the first access node transmitting the control message in the at least one protected time-slot.

7. The method of claim 1 , further comprising the second access node reducing an emitted spectral power in the least one protected time-slot to reduce the spectral interference with the first access node.

8. The method of claim 7 , wherein the reducing of the emitted spectral power comprises at least one of:

limiting a transmit power of the second access node to a predefined value;

at least partly interrupting the transmission of control data and/or payload data;

at least partly interrupting the transmission of control data and/or payload data on at least one frequency band of the spectrum.

9. The method of claim 1 , further comprising the first access node and/or the second access node selecting the at least one protected time-slot from the plurality of candidate time-slots.

10. The method of claim 9 , wherein the selecting is based on at least one of:

an urgency of the transmitting of the control message, wherein the urgency is a measure of the desired delay until the transmitting of the control message;

a velocity of the user equipment;

a data traffic load of the first access node and/or the second access node;

a count of pending handovers;

preconfigured rules.

11. The method of claim 1 , wherein the at least one protected time-slot is defined with respect to at least one radio frame of a sequence of radio frames used for data communication over a radio interface in the mobile communications network.

12. The method of claim 11 , wherein the indication explicitly indicates the at least one radio frame by means of at least one sequence number and/or the indication implicitly indicates the at least one radio frame by means of a predefined rule.

13. The method of claim 1 , further comprising the first access node and/or the user equipment determining the need for transmitting the control message.

14. The method of claim 13 , wherein the determining of the need for transmitting the control message is based on at least one of:

a signal level of the first access node measured at the user equipment;

a signal level of the second access node measured at the user equipment;

a transmit power of the first access node;

a transmit power of the second access node;

a signal level of the at least one further access node measured at the user equipment;

a transmit power of the at least one further access node;

a channel quality report;

history information on previously transmitted control messages;

a handover need;

a count of pending handover needs;

a velocity of the user equipment;

preconfigured rules.

15. The method of claim 1 , further comprising:

in response to the need for transmitting the control message, determining whether the at least one protected time-slot is required;

wherein the transmitting of the indication is selectively executed based on the determination of whether the at least one protected time-slot is required.

16. The method of claim 1 , wherein the control message is at least one of:

a handover message transmitted from the first access node to the user equipment, the handover message commanding the user equipment to execute a handover from the first access node to a further access node;

a downlink control message transmitted from the first access node to the user equipment, the downlink control message comprising a grant to the user equipment for transmission on an uplink;

a downlink control message transmitted from the first access node to the user equipment, the downlink control message comprising a command for configuration of a connectivity of the user equipment to access nodes and/or carriers;

an uplink control message transmitted from the user equipment to the first access node;

a channel quality report transmitted from the user equipment to the first access node.

17. An access node of a mobile communications network, the access node comprising:

a first interface for communicating with a further access node;

a second interface for communicating with a user equipment connected to the access node;

a processing circuit configured to:

control, in response to a need for transmitting a control message between the access node and the user equipment, transmission, to the further access node, of an indication of at least one protected time-slot for transmitting the control message; the transmitting of the indication prompting reduction of spectral interference caused by the further access node during the protected time-slot;

control transmission of the control message to take place in the at least one protected time-slot;

negotiate the at least one protected time-slot with the further access node, the negotiating including:

controlling the transmission of the indication;

sending a request message to the further access node, the request message indicating a plurality of candidate time-slots from which the at least one protected time-slot is selected;

receiving, from the further access node, an acknowledgement message positively and/or negatively acknowledging candidate time-slots from which the at least one protected time-slot is selected.

18. The access node of claim 17 , wherein the processing circuit is further configured to determine the need for transmitting the control message.

19. The access node of claim 17 , wherein the processing circuit is further configured to:

determine, in response to the need for transmitting the control message, whether the protected time-slot is required;

selectively execute the transmitting of the indication based on the determination of whether the protected time-slot is required.

20. A method of protecting transmission of a control message, in a mobile communications network, between a first access node and a user equipment, the method comprising:

in response to a need for transmitting the control message, transmitting, between the first access node and a second access node, an indication of at least one protected time-slot for transmitting the control message; the transmitting of the indication prompting reduction of spectral interference caused by the second access node during the at least one protected time-slot;

wherein the transmitting of the indication of the at least one protected time-slot is part of negotiating of the at least one protected time-slot between the first access node and the second access node, the negotiating including:

the second access node receiving, from the first access node, a request message indicating a plurality of candidate time-slots from which the at least one protected time-slot is selected; and

the second access node sending an acknowledgement message to the first access node, the acknowledgement message positively and/or negatively acknowledging candidate time-slots from which the at least one protected time-slot is selected.

21. An access node of a mobile communications network, comprising:

a first interface for communicating with a further access node;

a second interface for connecting via a radio interface to one or more user equipment connected to the access node;

a processing circuit configured to:

control, in response to a need for transmitting a control message between the further access node and a user equipment connected to the further access node, transmission to the further access node of an indication of at least one protected time-slot for transmitting the control message, the transmitting of the indication prompting reduction of a spectral interference caused by the access node during the protected time-slot;

control an emitted spectral power on the radio interface during the least one protected time-slot to reduce the spectral interference with the further access node;

negotiate the at least one protected time-slot with the further access node, the negotiating including:

controlling the transmission of the indication,

receiving a request message from the further access node, the request message indicating a plurality of candidate time-slots from which the at least one protected time-slot is selected;

sending an acknowledgement message to the further access node, the acknowledgement message positively and/or negatively acknowledging candidate time-slots from which the at least one protected time-slot is selected.

22. A computer program product stored in a non-transitory computer readable medium for protecting transmission of a control message, in a mobile communications network, between a first access node and a user equipment, the computer program product comprising software instructions which, when run on a processing circuit of the first access node, causes the first access node to:

in response to a need for transmitting the control message, transmit, between the first access node and a second access node, an indication of at least one protected time-slot for transmitting the control message; the transmitting of the indication prompting reduction of spectral interference caused by the second access node during the at least one protected time-slot;

wherein the transmitting of the indication of the at least one protected time-slot is part of negotiating of the at least one protected time-slot between the first access node and the second access node, the negotiating including:

sending, from the first access node to the second access node, a request message indicating a plurality of candidate time-slots from which the at least one protected time-slot is selected; and

receiving, from the second access node, an acknowledgement message positively and/or negatively acknowledging candidate time-slots from which the at least one protected time-slot is selected.

23. A computer program product stored in a non-transitory computer readable medium for protecting transmission of a control message, in a mobile communications network, between a first access node and a user equipment, the computer program product comprising software instructions which, when run on a processing circuit of a second access node, causes the second access node to:

in response to a need for transmitting the control message, transmit, between the first access node and a second access node, an indication of at least one protected time-slot for transmitting the control message; the transmitting of the indication prompting reduction of spectral interference caused by the second access node during the at least one protected time-slot;

wherein the transmitting of the indication of the at least one protected time-slot is part of negotiating of the at least one protected time-slot between the first access node and the second access node, the negotiating including:

the second access node receiving, from the first access node, a request message indicating a plurality of candidate time-slots from which the at least one protected time-slot is selected; and

the second access node sending an acknowledgement message to the first access node, the acknowledgement message positively and/or negatively acknowledging candidate time-slots from which the at least one protected time-slot is selected.