Radio link adaptation in communication systems

1. A method for performing link adaptation of a radio link, the method comprising a transmission node:

determining an estimation error of an estimated quality of the radio link;

determining a time limit for which the estimated quality of the radio link is valid, and

determining the estimation error and/or adapting a Modulation and Coding Scheme (MCS) decision input value if the time limit has elapsed;

determining whether a rank indicator of the transmission node and/or a neighboring transmission node has changed, compared to a rank indicator for which the quality of the radio link has been estimated;

determining the estimation error and/or adapting the MCS decision input value if the rank indicator has changed;

adapting the MCS decision input value, which is based on the estimated quality of the radio link, by increasing the MCS decision input value if the determined estimation error exceeds a predetermined threshold;

using a Hybrid Automatic Repeat Request (HARQ) transmission for throughput loss for an aggressive MCS caused by increasing the MCS decision input value if the determined estimation error exceeds a predetermined threshold; and

selecting a MCS based on the MCS input value as adapted.

2. The method of claim 1 , wherein adapting the MCS decision input value comprises adding an offset to the MCS decision input value.

3. The method of claim 1 , wherein determining an estimation error of the estimated quality of the radio link comprises:

estimating a Signal-to-Interference-and-Noise-Ratio (SINR) of the radio link; and

determining an estimation error level of the estimated SINR.

4. The method of claim 1 , wherein adapting the MCS decision input value comprises adding an offset having a predetermined constant value.

5. The method of claim 1 , wherein adapting the MCS decision input value comprises adding an offset having a value adapted based on the determined estimation error.

6. The method of claim 1 , wherein the adapting the MCS decision input value comprises adding an offset which is large enough such that a more aggressive MCS is selected than if the MCS is based on the estimated quality of the radio link.

7. The method of claim 1 , further comprising selecting a MCS corresponding to the MCS decision input value based on the estimated quality of the radio link if the determined estimation error is below a first predetermined threshold.

8. The method of claim 1 , further comprising determining an estimated quality of the radio link based on a transmission decision of at least one neighboring transmission node.

9. The method of claim 1 , further comprising determining an estimation error of the radio link quality based on a transmission decision of a neighboring transmission node.

10. The method of claim 1 , further comprising determining an estimation error of the radio link quality based on:

a Channel Quality Indicators (CQI);

a channel state information (CSI) process;

a Precoding Matrix Indicator (PMI);

a Rank Indicator (RI); and/or

receiver capabilities.

11. The method of claim 1 , further comprising determining an estimation error of the radio link quality based on comparing a plurality of Channel Quality Indicators (CQI), which are created based on the same transmission hypothesis.

12. The method of claim 1 , further comprising:

determining whether a number of interferers has changed compared to a number of interferers of the estimated quality of the radio link has been estimated; and

determining the estimation error and/or adapting the MCS decision input value if the number of interferers has changed.

13. The method of claim 1 , further comprising:

determining whether the power of interference has changed compared to a power of interference for which the quality of the radio link has been determined; and

determining the estimation error and/or adapting the MCS decision input value if the power of interference has changed above a predetermined threshold.

14. The method of claim 1 , further comprising:

determining whether a precoding matrix indicator of the transmission node and/or a neighboring transmission node has changed compared to a precoding matrix indicator for which the quality of the radio link has been estimated;

and determining the estimation error and/or adapting the MCS decision input value if the precoding matrix indicator has changed.

15. The method of claim 1 , wherein determining the estimation error, and/or the selecting the MCS is performed for each one of a plurality of successive transmission time intervals or a set of transmission time intervals.

16. A transmission node for performing link adaptation of a radio link, the transmission node comprising:

processing circuitry;

memory containing instructions executable by the processing circuitry whereby the transmission node is operative to:

determine an estimation error of an estimated quality of the radio link;

determine a time limit for which the estimated quality of the radio link is valid, and determining the estimation error and/or adapting a Modulation and Coding Scheme (MCS) decision input value if the time limit has elapsed;

determine whether a rank indicator of the transmission node and/or a neighboring transmission node has changed, compared to a rank indicator for which the quality of the radio link has been estimated;

determine the estimation error and/or adapting the MCS decision input value if the rank indicator has changed;

adapt the MCS decision input value, which is based on the estimated quality of the radio link, by increasing the MCS decision input value if the determined estimation error exceeds a predetermined threshold;

use a Hybrid Automatic Repeat Request (HARQ) transmission for throughput loss for an aggressive MCS caused by increasing the MCS decision input value if the determined estimation error exceeds a predetermined threshold; and

select a MCS based on the MCS input value as adapted.

17. A non-transitory computer readable recording medium storing a computer program product for controlling link adaptation of a radio link, the computer program product comprising software instructions which, when run on processing circuitry of a transmission node, causes the transmission node to:

determine an estimation error of an estimated quality of the radio link;

determine a time limit for which the estimated quality of the radio link is valid, and determining the estimation error and/or adapting a Modulation and Coding Scheme (MCS) decision input value if the time limit has elapsed;

determine whether a rank indicator of the transmission node and/or a neighboring transmission node has changed, compared to a rank indicator for which the quality of the radio link has been estimated;

determine the estimation error and/or adapting the MCS decision input value if the rank indicator has changed;

adapt the MCS decision input value, which is based on the estimated quality of the radio link, by increasing the MCS decision input value if the determined estimation error exceeds a predetermined threshold;

use a Hybrid Automatic Repeat Request (HARQ) transmission for throughput loss for an aggressive MCS caused by increasing the MCS decision input value if the determined estimation error exceeds a predetermined threshold; and

select a MCS based on the MCS input value as adapted.