Pre-distortion system and method

1. A pre-distortion system, comprising:

a pre-distortion circuit, configured to generate N pre-distortion output signals according to N digital intermediate frequency signals of different bands, N pre-distortion model coefficient vector sets, and N preset digital frequency conversion coefficient vector sets, wherein each pre-distortion model coefficient vector set comprises one in-band intermodulation distortion model coefficient vector, one cross-band modulation distortion model coefficient vector, and at least one out-of-band intermodulation distortion model coefficient vector, and wherein N is an integer greater than 2;

a transmission circuit, configured to generate a radio frequency analog signal according to the N pre-distortion output signals;

a power amplifier, configured to perform amplification processing according to the radio frequency analog signal, so as to generate a radio frequency analog signal that has undergone the amplification processing;

a feedback circuit, configured to generate N digital intermediate frequency feedback signals according to the radio frequency analog signal that has undergone the amplification processing; and

a learning circuit, configured to generate the N pre-distortion model coefficient vector sets, and to generate N new pre-distortion model coefficient vector sets according to the N pre-distortion output signals and the N digital intermediate frequency feedback signals.

2. The pre-distortion system according to claim 1 , wherein the pre-distortion circuit comprises:

a first sub-circuit, configured to generate N pre-distortion model vector sets B 1 , B 2 , . . . , B S , . . . , and B N according to the N digital intermediate frequency signals, wherein 1≦S ≦N, B S =(B S (in) , B S (cross) , B S (out) 1 , B S (out) 2 , . . . , B S (out) P ), P is a quantity of out-of-band intermodulation distortion components corresponding to B S , B S (in) is an in-band intermodulation distortion model vector in B S , B S (cross) is a cross-band modulation distortion model vector in B S , and B S (out) P is an out-of-band intermodulation distortion model vector of a P th out-of-band intermodulation distortion component in B S ;

a second sub-circuit, configured to acquire the N pre-distortion model coefficient vector sets, wherein the N pre-distortion model coefficient vector sets comprise ω 1 , ω 2 , . . . , ω S , . . . , and ω N , wherein ω S =(ω S (in) , ω S (cross) , ω S (out) 1 , ω S (out) 2 , . . . , ω S (out) P ), ω S (in) is an in-band intermodulation distortion model coefficient vector in ω S , ω S (cross) is a cross-band modulation distortion model coefficient vector in ω S , and ω S (out) P is an out-of-band intermodulation distortion model coefficient vector corresponding to a P th out-of-band intermodulation distortion component in ω S ;

a third sub-circuit, configured to generate the N preset digital frequency conversion coefficient vector sets, wherein the N preset digital frequency conversion coefficient vector sets comprise F 1 , F 2 , . . . , F S , . . . , and F N , wherein F S =(F S (in) , F S (cross) , F S (out) 1 , F S (out) 2 , . . . , F S (out) P ), F S (in) is an in-band intermodulation distortion digital frequency conversion coefficient vector in F S , a quantity of elements in F S (in) is equal to a quantity of elements in B S (in) and equal to a quantity of elements in ω S (in) , and the elements in F S (in) are all 1; F S (cross) is a cross-band modulation distortion digital frequency conversion coefficient vector in F S , a quantity of elements in F S (cross) is equal to a quantity of elements in B S (cross) and equal to a quantity of elements in ω S (cross) , and the elements in F S (cross) are all 1; F S (out) P is an out-of-band intermodulation distortion digital frequency conversion coefficient vector of a P th out-of-band intermodulation distortion component in F S , a quantity of elements in F S (out) P is equal to a quantity of elements in B S (out) P and equal to a quantity of elements in ω S (out) P , and the elements in F S (out) P are all e j2πnf S (out) P/f sample ; f S (out) P is a difference between a carrier frequency of an S th digital intermediate frequency signal and a center frequency of the P th out-of-band intermodulation distortion component; and f sample is a sampling rate of each digital intermediate frequency signal; and

a fourth sub-circuit, configured to generate the N pre-distortion output signals according to the N pre-distortion model vector sets, the N pre-distortion model coefficient vector sets, and the N preset digital frequency conversion coefficient vector sets, wherein the N pre-distortion output signals comprise y 1 , y 2 , . . . , y S , . . . , and y N , and wherein y S =B S (in) ·ω S (in) ·F S (in) +B S (cross) ·ω S (cross) ·F S (cross) +B S (out) 1 ·ω S (out) 1 ·F S (out) 1 + . . . +B S (out) P ·ω S (out) P ·F S (out) P .

3. The pre-distortion system according to claim 2 , wherein the learning circuit is configured to determine an S th pre-distortion model coefficient vector set in the N new pre-distortion model coefficient vector sets by using the following formulas:

ω

S

=

(

U

1

H

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U

S

)

-

1

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U

S

H

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Y

S

Y

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=

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y

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n

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y

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n

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2

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,

…

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y

S

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n

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T

U

S

=

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u

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n

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u

S

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(

n

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+

2

)

…

u

S

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(

n

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]

,

wherein Q is a quantity of sampling points of an S th digital intermediate frequency feedback signal, and u s is a pre-distortion learning vector set generated according to the S th digital intermediate frequency feedback signal and an S th digital frequency conversion coefficient vector set.

4. The pre-distortion system according to claim 1 , further comprising:

a preprocessing circuit, configured to generate the N digital intermediate frequency signals according to N baseband signals of different bands, and to input the N digital intermediate frequency signals into the pre-distortion circuit.

5. A pre-distortion method, comprising:

generating, by a pre-distortion system, N pre-distortion output signals according to N digital intermediate frequency signals of different bands, N pre-distortion model coefficient vector sets, and N preset digital frequency conversion coefficient vector sets, wherein each pre-distortion model coefficient vector set comprises one in-band intermodulation distortion model coefficient vector, one cross-band modulation distortion model coefficient vector, and at least one out-of-band intermodulation distortion model coefficient vector, and wherein N is an integer greater than 2;

generating, by the pre-distortion system, a radio frequency analog signal according to the N pre-distortion output signals;

performing, by the pre-distortion system, amplification processing according to the radio frequency analog signal, so as to generate a radio frequency analog signal that has undergone the amplification processing;

generating, by the pre-distortion system, N digital intermediate frequency feedback signals according to the radio frequency analog signal that has undergone the amplification processing; and

generating, by the pre-distortion system, N new pre-distortion model coefficient vector sets according to the N pre-distortion output signals and the N digital intermediate frequency feedback signals.

6. The method according to claim 5 , wherein generating the N pre-distortion output signals comprises:

generating N pre-distortion model vector sets B 1 , B 2 , . . . , B S , . . . , and B N according to the N digital intermediate frequency signals, wherein 1≦S≦N, B S =(B S (in) , B S (cross) , B S (out) 1 , B S (out) 2 , . . . , B S (out) P ), B S (in) is an in-band intermodulation distortion model vector in B S , P is a quantity of out-of-band intermodulation distortion components corresponding to B S , B S (cross) is a cross-band modulation distortion model vector in B S , and B S (out) P is an out-of-band intermodulation distortion model vector of a P th out-of-band intermodulation distortion component in B S ;

acquiring the N pre-distortion model coefficient vector sets, wherein the N pre-distortion model coefficient vector sets comprise ω 1 , ω 2 , . . . , ω S , . . . , and ω N , wherein ω S =(ω S (in) , ω S (cross) , ω S (out) 1 , ω S (out) 2 , . . . , ω S (out) P ), ω S (in) is an in-band intermodulation distortion model coefficient vector in ω S , ω S (cross) is a cross-band modulation distortion model coefficient vector in ω S , and ω S (out) P is an out-of-band intermodulation distortion model coefficient vector corresponding to a P th out-of-band intermodulation distortion component in ω S ;

generating the N preset digital frequency conversion coefficient vector sets, wherein the N preset digital frequency conversion coefficient vector sets comprise F 1 , F 2 , . . . , F S , . . . , and F N , wherein F S =(F S (in) , F S (cross) , F S (out) 1 , F S (out) 2 , . . . , F S (out) P ), F S (in) is an in-band intermodulation distortion digital frequency conversion coefficient vector in F S , a quantity of elements in F S (in) is equal to a quantity of elements in B S (in) and equal to a quantity of elements in ω S (in) , and the elements in F S (in) are all 1; F S (cross) is a cross-band modulation distortion digital frequency conversion coefficient vector in F S , a quantity of elements in F S (cross) is equal to a quantity of elements in B S (cross) and equal to a quantity of elements in ω S (cross) , and the elements in F S (cross) are all 1; F S (out) P is an out-of-band intermodulation distortion digital frequency conversion coefficient vector of a P th out-of-band intermodulation distortion component in F S , a quantity of elements in F S (out) P is equal to a quantity of elements in B S (out) P and equal to a quantity of elements in ω S (out) P , and the elements in F S (out) P are all e j2πnf S (out) P/f sample ; f S (out) P is a difference between a carrier frequency of an S th digital intermediate frequency signal and a center frequency of the P th out-of-band intermodulation distortion component; and f sample is a sampling rate of each digital intermediate frequency signal; and

generating the N pre-distortion output signals according to the N pre-distortion model vector sets, the N pre-distortion model coefficient vector sets, and the N preset digital frequency conversion coefficient vector sets, wherein the N pre-distortion output signals comprise y 1 , y 2 , . . . , y S , . . . , and y N , and wherein y S =B S (in) ·ω S (in) ·F S (in) +B S (cross) ·ω S (cross) ·F S (cross) +B S (out) 1 ·ω S (out) 1 ·F S (out) 1 + . . . +B S (out) P ·ω S (out) P ·F S (out) P .

7. The method according to claim 6 , wherein generating the N new pre-distortion model coefficient vector sets comprises:

determining an S th pre-distortion model coefficient vector set in the N new pre-distortion model coefficient vector sets by using the following formulas:

ω

S

=

(

U

1

H

⁢

U

S

)

-

1

⁢

U

S

H

⁢

Y

S

Y

S

=

[

y

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(

n

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+

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y

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n

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,

y

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U

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=

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u

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u

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+

2

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…

u

S

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(

n

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]

,

 wherein Q is a quantity of sampling points of an S th digital intermediate frequency feedback signal, and u S is a pre-distortion learning vector set generated according to the S th digital intermediate frequency feedback signal and an S th digital frequency conversion coefficient vector set.

8. The method according to claim 5 , wherein before generating the N pre-distortion output signals, the method further comprises:

generating the N digital intermediate frequency signals according to N baseband signals of different bands.