Non-contiguous carrier aggregation

1. A method of operating a user equipment for measuring non-contiguous carriers, the method comprising:

changing a position of a local oscillator to be in a middle of the non-contiguous carriers;

measuring the non-contiguous carriers simultaneously to generate a measurement;

estimating a power level of an interferer in a gap in the non-contiguous carriers that creates image interference; and

compensating the measurement dependent on the power level of the interferer and an image rejection factor.

2. The method as claimed in claim 1 , wherein compensating the measurement comprise compensating the measurement conditional on the power level of the interferer being less than a first threshold.

3. The method as claimed in claim 1 , wherein measuring the non-contiguous carriers comprises:

calculating a joint power and energy-per-chip to noise-plus-interference ratio for the non-contiguous carriers; and

computing a per-carrier power and energy-per-chip to noise-plus-interference ratio.

4. The method as claimed in claim 3 , wherein:

estimating the power level of the interferer comprises estimating the power level of the interferer that creates the image interference and computing a level of the image interference in one of the carriers; and

compensating the measurement comprises subtracting the level of the image interference from the per-carrier power and energy—per-chip to noise-plus-interference of the one of the carriers.

5. The method as claimed in claim 4 , wherein compensating the measurement comprises compensating the measurement conditional on a ratio of the power level of the interferer to the per-carrier power of the one of the carriers being less than a second threshold.

6. The method as claimed in claim 4 , further comprising:

computing a difference between a signal-to-noise ratio of the one of the carriers and an ideal signal-to-noise ratio of the one of the carriers with the image interference removed;

mapping the difference into a channel quality indicator (CQI) table to find an ideal CQI value the user equipment would support if the interferer was not there; and

informing a NodeB about a difference between a realistic CQI value and the ideal CQI value.

7. The method as claimed in claim 6 , wherein informing the NodeB comprises reporting the realistic CQI value and the ideal CQI value to the NodeB when requested by the NodeB.

8. The method as claimed in claim 7 , wherein the realistic CQI value and the ideal CQI value are multiplexed using code division multiplexing.

9. The method as claimed in claim 7 , wherein the realistic CQI value and the ideal CQI value are multiplexed using time division multiplexing.

10. The method as claimed in claim 1 , wherein measuring the non-contiguous carriers comprises measuring the non-contiguous carriers simultaneously during one measurement gap.

11. The method as claimed in claim 1 , wherein the method is performed responsive to a request for the measurement received from a NodeB.

12. The method as claimed in claim 1 , wherein the method is performed autonomously by the user equipment.

13. A user equipment configured to measure non-contiguous carriers, the user equipment comprising:

a receiver configured to receive the non-contiguous carriers;

a local oscillator;

a processing circuit configured to:

change a position of the local oscillator to be in a middle of the non-contiguous carriers;

measure the non-contiguous carriers simultaneously to generate a measurement;

estimate a power level of an interferer in a gap in the non-contiguous carriers that creates image interference; and

compensate the measurement dependent on the power level of the interferer and an image rejection factor.