Method and network node for sector selection

1. A method for sector selection performed in a communication system providing wireless communication to a communication device, the communication system being configured for shared cell deployment, the shared cell comprising at least two sectors, the communication system being configured for link adaptation of a radio link between the communication device and the shared cell, the method comprising:

selecting, for the communication device, a first set of sectors for use in downlink transmissions to the communication device; wherein the first set of sectors is selected based on path loss measurements per sector;

after selecting the first set of sectors, transmitting data to the communication device using the first set of sectors;

determining, for the communication device, a link adaptation parameter value relating to the link adaptation, wherein the link adaptation parameter value indicates if the selected first set of sectors is sufficient in view of data throughput or signal quality;

determining whether the determined link adaptation parameter value satisfies a condition; wherein the condition comprises extending the selected first set of sectors whenever an outer loop compensation exceeds a pre-configurable threshold;

as a result of determining that the link adaptation parameter value satisfies the condition, defining a second set of sectors by adding at least one additional sector to the first set of sector, wherein the second set of sectors includes each sector included in the first set of sectors plus the at least one additional sector which is not included in the first set of sectors such that the second set of sectors is larger than the first set of sectors by at least one sector; and

after defining the second set of sectors transmitting data to the communication device using the second set of sectors.

2. The method of claim 1 , wherein the link adaptation comprises a downlink link adaptation,

the link adaptation parameter value comprises a Signal-to-Interference and Noise ratio (SINR) adjustment value,

the threshold comprises a SINR adjustment threshold, and

determining the link adaptation parameter value comprises:

receiving, from the communication device, a feedback report relating to a downlink transmission, the feedback report comprising a positive or negative acknowledgment, and

determining the link adaptation parameter value based on the received feedback report.

3. The method of claim 1 , wherein the link adaptation comprises a downlink link adaptation and wherein the link adaptation parameter value comprises a block error rate and wherein determining the link adaptation parameter value comprises:

determining a block error rate for the communication device based on feedback reports relating to downlink transmissions to the communication device.

4. The method of claim 3 , wherein the determining of the block error rate is based on at least two feedback reports, the at least two feedback report relating to respective downlink transmission to the communication device.

5. The method of claim 3 , wherein the feedback reports comprise one or both of: a positive acknowledgment and a negative acknowledgment.

6. The method of claim 1 , comprising:

as a result of adding an additional sector to the first set of sectors, starting a time counter;

determining, based on the time counter, whether at least a threshold amount of time has elapsed since the additional sector was added to the first set of sectors;

as a result of determining that at least the threshold amount of time has elapsed since the additional sector was added to the first set of sectors, defining a third set of sectors that is smaller than the second set of sectors by removing a sector from the second set of sectors; and

using the third set of sectors to transmit data to the communication device.

7. The method as claimed of claim 1 , wherein the selecting the first set of sectors comprises:

receiving, from one or more of the sectors, uplink channel measurements relating to the communication device, and

selecting the first set of sectors based on the uplink channel measurements.

8. The method of claim 7 , wherein the selecting comprises determining, for each respective sector, path gain to the communication device based on the received uplink channel measurements and selecting N sectors having N highest path gains as the first set of sectors.

9. The method of claim 1 , wherein the link adaptation parameter value comprises one or more of: block error rate, signal-to-interference and noise ratio, throughput degradation, and increased number of retransmissions.

10. The method of claim 1 , wherein the additional sector has the highest path gain to the communication device among sectors not currently used by the communication device.

11. The method of claim 1 , wherein the method is performed by a network node of the communication system.

12. A communication system for sector selection, the communication system providing wireless communication to a communication device, the communication system being configured for shared cell deployment, the communication system being configured for link adaptation of a radio link between the communication device and a shared cell comprising at least two sectors, the communication system comprising at least one processor and memory, the memory containing instructions executable by the processor, whereby the communication system is operative to:

select, for the communication device, a first set of sectors for use in downlink transmissions to the communication device; wherein the first set of sectors is selected based on path loss measurements per sector;

after selecting the first set of sectors transmitting data to the communication device using the first set of sectors;

determine, for the communication device, a link adaptation parameter value relating to the link adaptation, wherein the link adaptation parameter value indicates if the selected first set of sectors is sufficient in view of data throughput or signal quality

determine whether the determined link adaptation parameter value satisfies a condition; wherein the condition comprises extending the selected first set of sectors whenever an outer loop compensation exceeds a pre-configurable threshold;

as a result of determining that the link adaptation parameter value satisfies the condition, define a second set of sectors by adding at least one additional sector to the first set of sector, wherein the second set of sectors includes each sector included in the first set of sectors plus the at least one additional sector which is not included in the first set of sectors such that the second set of sectors is larger than the first set of sectors by at least one sector; and

after defining the second set of sectors transmitting data to the communication device using the second set of sectors.

13. The communication system of claim 12 , wherein

the link adaptation comprises a downlink link adaptation,

the link adaptation parameter value comprises a Signal-to-Interference and Noise ratio (SINR) adjustment value,

the threshold comprises a SINR adjustment threshold, and

determining the link adaptation parameter value comprises:

receiving, from the communication device, a feedback report relating to a downlink transmission, the feedback report comprising a positive or negative acknowledgment, and

determining the link adaptation parameter value based on the received feedback report.

14. The communication system of claim 12 , wherein the link adaptation comprises a downlink link adaptation and wherein the link adaptation parameter value comprises a block error rate and wherein the communication system is configured to determine the link adaptation parameter value by:

determining a block error rate for the communication device based on feedback reports relating to downlink transmissions to the communication device.

15. The communication system of claim 14 , wherein the communication system is configured to determine the block error rate based on at least two feedback reports, the at least two feedback report relating to respective downlink transmission to the communication device.

16. The communication system of claim 14 , wherein the feedback reports comprise positive and/or negative acknowledgment messages.

17. The communication system of claim 12 , wherein the communication system is configured to:

start a time counter as a result of adding an additional sector to the first set of sectors;

determine, based on the time counter, whether at least a threshold amount of time has elapsed since the additional sector was added to the first set of sectors;

define a third set of sectors that is smaller than the second set of sectors by removing a sector from the second set of sectors as a result of determining that at least the threshold amount of time has elapsed since the additional sector was added to the first set of sectors; and

use the third set of sectors to transmit data to the communication device.

18. The communication system of claim 12 , wherein the communication system is configured to select the first set of sectors by:

receiving, from one or more of the sectors, uplink channel measurements relating to the communication device, and

selecting the first set of sectors based on the uplink channel measurements.

19. The communication system of claim 18 , wherein the communication system is configured to select by determining, for each respective sector, path gain to the communication device based on the received uplink channel measurements and selecting N sectors having N highest path gains as the first set of sectors.

20. The communication system of claim 12 , wherein the link adaptation parameter value comprises block error rate, signal-to-interference and noise ratio, throughput degradation or increased number of retransmissions.

21. The communication system of claim 12 , wherein the communication system is configured to adapt by adding a sector having the highest path gain to the communication device among sectors not currently used by the communication device.

22. The communication system of claim 12 , wherein the at least one processor and memory are housed within a single network node.

23. A computer program product comprising a non-transitory computer readable medium storing a computer program for sector selection for a communication system providing wireless communication to a communication device, the communication system being configured for shared cell deployment, the communication system being configured for link adaptation of a radio link between the communication device and a sector of a shared cell, the computer program comprising computer program code, which, when run on the communication system causes the communication system to:

select, for the communication device, a first set of sectors for use in downlink transmissions to the communication device; wherein the first set of sectors is selected based on path loss measurements per sector;

after selecting the first set of sectors transmitting data to the communication device using the first set of sectors;

determine, for the communication device, a link adaptation parameter value relating to the link adaptation, wherein the link adaptation parameter value indicates if the selected first set of sectors is sufficient in view of data throughput or signal quality

determine whether the determined link adaptation parameter value satisfies a condition; wherein the condition comprises extending the selected first set of sectors whenever an outer loop compensation exceeds a pre-configurable threshold;

as a result of determining that the link adaptation parameter value satisfies the condition, define a second set of sectors by adding at least one additional sector to the first set of sector, wherein the second set of sectors includes each sector included in the first set of sectors plus the at least one additional sector which is not included in the first set of sectors such that the second set of sectors is larger than the first set of sectors by at least one sector; and

after defining the second set of sectors transmitting data to the communication device using the second set of sectors.