Slot-based CSI report configuration for dynamic TDD

1. A method for operating a cell, performed by a network node, the method comprising:

transmitting a frame comprising a set of slots;

receiving Channel State Information, CSI, reports at least indicative of interference measured by a user equipment using the set of slots;

estimating a transmission direction pattern of an adjacent cell relative to a transmission direction pattern of the cell based on the received CSI reports;

transmitting a signal to the user equipment based on the estimated transmission direction pattern of the adjacent cell;

calculating a statistical measure of interference levels, of each slot of the set of slots, using the CSI reports and previously received historical CSI reports;

the transmission direction pattern of the adjacent cell estimated using the statistical measure;

determining that the statistical measure is stationary; and

selecting only one slot out of the corresponding slots having the stationary statistical measure for later CSI reporting instances.

2. The method according to claim 1 , wherein all slots configurable for downlink transmission, by the network node, are selected to the set of slots.

3. The method according to claim 2 , wherein all slots configurable for one of uplink and downlink transmission, by the network node, are selected to the set of slots.

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

sending a Channel State Information, CSI, measurement configuration message indicative of the set of slots to the user equipment.

5. The method according to claim 2 , wherein the measurement configuration message is further indicative of:

interference measurements in every slot of the set of slots; and

channel measurements in a subset of the set of slots.

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

selecting an updated set of slots being selected from all slots comprised in the frame; and

repeating the steps of claim 1 using the updated set.

7. The method according to claim 1 , wherein all slots configurable for one of uplink and downlink transmission, by the network node, are selected to the set of slots.

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

sending a Channel State Information, CSI, measurement configuration message indicative of the set of slots to the user equipment.

9. The method according to claim 8 , wherein the measurement configuration message is further indicative of:

interference measurements in every slot of the set of slots; and

channel measurements in a subset of the set of slots.

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

selecting an updated set of slots being selected from all slots comprised in the frame; and

repeating the steps of claim 1 using the updated set.

11. The method according to claim 10 , wherein the updated set is selected only for every Nth frame, wherein the number N is selected as a multiple of a total number of slots in the frame.

12. The method according to claim 11 , wherein the number N is selected dependent on a channel measure indicative of how fast a channel between the network node and the user equipment changes.

13. The method according to claim 1 , wherein the CSI reports are further indicative of channel quality of one or more slots of the set of slots, wherein the transmitting further comprises:

estimating channel quality for the remaining slots comprised in the frame using the one or more transmission direction patterns of one or more adjacent cells and the channel quality of the CSI report; and

at least one of scheduling slot transmission and performing slot link adaptation using the channel quality of the CSI report and the estimated channel quality.

14. A method performed by a user equipment, the method comprising:

receiving a Channel State Information, CSI, measurement configuration message indicative of a set of slots comprised in a frame from a network node;

measuring interference using the set of slots;

sending a Channel State Information, CSI, report indicative of interference measured using the set of slots; and

receiving a signal from the network node, the signal having been transmitted based on an estimated transmission direction pattern of an adjacent cell, and been based on a calculated statistical measure of interference levels, of each slot of the set of slots, using the CSI reports and previously received historical CSI reports, the transmission direction pattern of the adjacent cell having been estimated using the statistical measure, having been determined that the statistical measure is stationary, and having been selected as only one slot out of the corresponding slots, having the stationary statistical measure, for later CSI reporting instances.

15. The method according to claim 14 , wherein the measurement configuration message is further indicative of interference measurements to be performed in every slot of the set of slots, and, channel measurements to be performed in a subset of the set of slots; and

wherein interference is measured in every slot of the set of slots and the channel is measured in a subset of the set of slots.

16. A network node comprising:

processing circuitry configured to:

transmit a frame comprising a set of slots;

receive Channel State Information, CSI, reports at least indicative of interference measured by a user equipment using the set of slots;

estimate a transmission direction pattern of an adjacent cell relative a transmission direction pattern of the cell based on the received CSI reports;

transmit a signal to the user equipment based on the estimated transmission direction pattern of the adjacent cell;

calculate a statistical measure of interference levels, of each slot of the set of slots, using the CSI reports and previously received historical CSI reports;

the transmission direction pattern of the adjacent cell estimated using the statistical measure;

determine that the statistical measure is stationary; and

select only one slot out of the corresponding slots, having the stationary statistical measure, for later CSI reporting instances.

17. A user equipment comprising:

processing circuitry configured to:

receive a Channel State Information, CSI, measurement configuration message indicative of a set of slots comprised in a frame from a network node;

measure interference using the set of slots;

send a Channel State Information, CSI, report indicative of interference measured using the set of slots; and

receive a signal from the network node, the signal being configured to have been transmitted based on an estimated transmission direction pattern of an adjacent cell, using the CSI reports and previously received historical CSI reports, the transmission direction pattern of the adjacent cell estimated using the statistical measure, and having been determines that the statistical measure is stationary, and having been selected as only one slot out of the corresponding slots, having the stationary statistical measure, for later CSI reporting instances.