Apparatus and method for cubic metric computation in dual-carrier and multi-carrier wireless communication system

1. A method, comprising:

receiving, at a radio frequency integrated circuit, at least two sets of gain values, wherein each set of gain values denotes the gains of a set of code channels that are carried by a carrier of at least two carriers;

receiving, at the radio frequency integrated circuit, at least two power levels, each of the at least two power levels being allocated to a different carrier of the at least two carriers;

calculating, at the radio frequency integrated circuit, a cubic metric based on the received at least two sets of gain values and the received at least two power levels signaling the cubic metric, or a value derived from the cubic metric, to a baseband integrated circuit, in order to determine a correct transmit power level to reduce non-linearity distortion.

2. The method of claim 1 , wherein calculating the cubic metric further comprises:

selecting at least one of the at least two carriers as a reference carrier; and

based on the selection, adjusting at least one of the at least two sets of gain values by a parameter that is derived from the received at least two sets of gain values and the received at least two power levels.

3. The method of claim 2 , wherein the parameter is equal to

P

n

⁢

(

β

1

,

1

2

+

β

1

,

2

2

+

…

+

β

1

,

L

1

2

)

P

1

⁢

(

β

n

,

1

2

+

β

n

,

2

2

+

…

+

β

n

,

L

n

2

)

,

wherein n is the index of the carrier that carries the set of code channels whose gain values (β n,1 , β n,2 , . . . , β nL n ) are to be adjusted, L n is the number of the code channels carried by the carrier n, (β 1,1 , β 1,2 , . . . , β 1,L 1 ) are the gain values of the code channels carried by the referenced carrier, L 1 is the number of the code channels of the referenced carrier, P n is the power level allocated to the carrier n, and P 1 is the power level allocated to the referenced carrier.

4. The method of claim 1 , further comprising:

scaling, at the radio frequency integrated circuit, the signal of carrier n by

P

n

∑

k

=

1

K

⁢

P

k

,

where P n is the power level allocated to the carrier n and K is the number of carriers.

5. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code,

wherein the at least one memory and the computer program code are configured to,

with the at least one processor, cause the apparatus at least to

receive at least two sets of gain values, wherein each set of gain values denotes the gains of a set of code channels that are carried by each of at least two carriers,

receive at least two power levels that are allocated to the at least two carriers, and

calculate a cubic metric based on the received at least two sets of gain values and the received at least two power levels, in order to determine a correct transmit power level to reduce non-linearity distortion.

6. The apparatus of claim 5 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to further

select at least one of the at least two carriers as the referenced carrier; and

based on the selection, adjusting at least one of the at least two sets of gain values by a parameter that is derived from the received at least two sets of gain values and the received at least two power levels.

7. The apparatus of claim 6 , wherein the parameter is equal to

P

n

⁢

(

β

1

,

1

2

+

β

1

,

2

2

+

…

+

β

1

,

L

1

2

)

P

1

⁢

(

β

n

,

1

2

+

β

n

,

2

2

+

…

+

β

n

,

L

n

2

)

,

wherein n is the index of the carrier that carries the set of code channels whose gain values (β n,1 , β n,2 , . . . , β n,L n ) are to be adjusted, L n is the number of the code channels carried by the carrier n, (β 1,1 , β 1,2 , . . . , β 1,L 1 ) are the gain values of the code channels carried by the referenced carrier, L 1 is the number of the code channels of the referenced carrier, P n is the power level allocated to the carrier n, and P 1 is the power level allocated to the referenced carrier.

8. The apparatus of claim 5 , wherein the apparatus is a radio frequency integrated circuit further comprising:

a digital-to-analog converter, a low pass filter and a power amplifier.

9. The apparatus of claim 5 , wherein the apparatus is a user terminal further comprising:

a baseband integrated circuit and baseband software configured to provide the at least two sets of gain values and the at least two power levels.

10. The apparatus of claim 5 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to further

scale the signal of carrier n by

P

n

∑

k

=

1

K

⁢

P

k

,

where P n is the power level allocated to the carrier n and K is the number of carriers.

11. A computer program embodied on a non-transitory computer readable medium, the computer program, when executed by a processor, causes the processor to:

receive at least two sets of gain values, wherein each set of gain values denotes the gains of a set of code channels that are carried by each of at least two carriers;

receive at least two power levels that are allocated to the at least two carriers; and

calculate a cubic metric based on the received at least two sets of gain values and the received at least two power levels, in order to determine a correct transmit power level to reduce non-linearity distortion.

12. The computer program embodied on the non-transitory computer readable medium of claim 11 , wherein the computer program, when executed by the processor, further causes the processor to:

select at least one of the at least two carriers as the referenced carrier; and

adjust, based on the selection, at least one of the at least two sets of gain values by a parameter that is derived from the received at least two sets of gain values and the received at least two power levels.

13. The computer program embodied on the non-transitory computer readable medium of claim 12 , wherein the parameter is equal to

P

n

⁢

(

β

1

,

1

2

+

β

1

,

2

2

+

…

+

β

1

,

L

1

2

)

P

1

⁢

(

β

n

,

1

2

+

β

n

,

2

2

+

…

+

β

n

,

L

n

2

)

,

wherein n is the index of the carrier that carries the set of code channels whose gain values (β n,1 , β n,2 , . . . , β n,L n ) are to be adjusted, L n is the number of the code channels carried by the carrier n, (β 1,1 , β 1,2 , . . . , β 1,L 1 ) are the gain values of the code channels carried by the referenced carrier, L 1 is the number of the code channels of the referenced carrier, P n is the power level allocated to the carrier n, and P 1 is the power level allocated to the referenced carrier.

14. The computer program embodied on the non-transitory computer readable medium of claim 12 , wherein the computer program, when executed by the processor, further causes the processor to:

scale the signal of carrier n by

P

n

∑

k

=

1

K

⁢

P

k

,

where P n is the power level allocated to the carrier n and K is the number of carriers.

15. An apparatus, comprising: means for receiving at least two sets of gain values, wherein each set of gain values denotes the gains of a set of code channels that are carried by each of at least two carriers;

means for receiving at least two power levels that are allocated to the at least two carriers; and

means for calculating a cubic metric based on the received at least two sets of gain values and the received at least two power levels, in order to determine a correct transmit power level to reduce non-linearity distortion.

16. The apparatus of claim 15 , further comprising:

means for selecting at least one of the at least two carriers as the referenced carrier; and

means for adjusting, based on the selection, at least one of the at least two sets of gain values by a parameter that is derived from the received at least two sets of gain values and the received at least two power levels.

17. The apparatus of claim 16 , wherein the parameter is equal to

P

n

⁢

(

β

1

,

1

2

+

β

1

,

2

2

+

…

+

β

1

,

L

1

2

)

P

1

⁢

(

β

n

,

1

2

+

β

n

,

2

2

+

…

+

β

n

,

L

n

2

)

,

wherein n is the index of the carrier that carries the set of code channels whose gain values (β n,1 , β n,2 , . . . , β n,L n ) are to be adjusted, L n is the number of the code channels carried by the carrier n, (β 1,1 , β 1,2 , . . . , β 1,L 1 ) are the gain values of the code channels carried by the referenced carrier, L 1 is the number of the code channels of the referenced carrier, P n is the power level allocated to the carrier n, and P 1 is the power level allocated to the referenced carrier.

18. The apparatus of claim 15 , further comprising:

means for scaling the signal of carrier n by

P

n

∑

k

=

1

K

⁢

P

k

,

where P n is the power level allocated to the carrier n and K is the number of carriers.