Method for controlling outer loop power in a WCDMA system

1. A method for controlling outer loop power, comprising the following steps of:

a) measuring a BER, and calculating an error between measured BER and a target BER and a change value of the error;

b) determining a fuzzy value of the error and a fuzzy value of the change of the error;

c) calculating a fuzzy value of a SNR threshold adjusting step value in accordance with the fuzzy value of the error and the fuzzy value of the change of the error;

d) determining an actual SNR threshold adjusting step value based on the calculated fuzzy value of the SNR threshold adjusting step value; and

e) adjusting a SNR threshold in accordance with the actual SNR threshold adjusting step value.

2. The method for controlling outer loop power as claimed in claim 1 , wherein said step a) is performed as follows:

the error is −10, when measured BER=0;

the error is log10 (measured BER/target BER), when measured BER≠0; and

the change of the error is a current calculated error minus a previous calculated error.

3. The method for controlling outer loop power as claimed in claim 1 , wherein the fuzzy value of the error and the fuzzy value of the change of the error in said step b) are determined by a table below:

Fuzzy

value

−3

2

−1

0

1

2

3

Error

<−0.7

[−0.7,

[−0.3,

[−0.05,

[0.05,

[0.3, 0.7]

>0.7

−0.3]

−0.05]

0.05]

0.3]

change

<−0.7

[−0.7,

[−0.3,

[−0.1,

[0.1,

[0.3, 0.7]

>0.7

of error

−0.3]

−0.1]

0.1]

0.3].

4. The method for controlling outer loop power as claimed in claim 2 , wherein the fuzzy value of the error and the fuzzy value of the variance value of the error in said step b) are determined by a table below:

fuzzy

value

−3

−2

−1

0

1

2

3

error

<−0.7

[−0.7,

[−0.3,

[−0.05,

[0.05,

[0.3, 0.7]

>0.7

−0.3]

−0.05]

0.05]

0.3]

change

<−0.7

[−0.7,

[−0.3,

[−0.1,

[0.1,

[0.3, 0.7]

>0.7

of error

−0.3]

−0.1]

0.1]

0.3].

5. The method for controlling outer loop power as claimed in claim 1 , wherein said step c) is performed in accordance with the following equations;

if |error fuzzy value|<2, SNR threshold adjusting step fuzzy value=int(a 1 ,* error fuzzy value+(1−a 1 )*error change fuzzy value grade); and

if |error fuzzy value |≧2, SNR threshold adjusting step fuzzy value=int(a 2 * error fuzzy value+(1−a 2 )*error change fuzzy value),

wherein, int(x) denotes rounding, and both a 1 and a 2 are adjustable coefficients and meet the following requirement:

0≦a 1 ≦a 2 ≦<1.

6. The method for controlling outer loop power as claimed in claim 3 , wherein said step c) is performed in accordance with the following equations:

if |error fuzzy value |≦2, SNR threshold adjusting step fuzzy value=int(a 1 * error fuzzy value+(1−a 1 ) *error change fuzzy value); and

if |error fuzzy value |≧2, SNR threshold adjusting step fuzzy value=int(a 2 * error fuzzy value+(1−a 2 ) *error change fuzzy value),

wherein, int(x) denotes rounding, and both a 1 and a 2 are adjustable coefficients and meet the following requirement:

0≦a 1 ≦a 2 ≦1.

7. The method for controlling outer loop power as claimed in claim 4 , wherein said step c) is performed in accordance with the following equations:

if |error fuzzy value |<2, SNR threshold adjusting step fuzzy value=int(a 1 *error fuzzy value+(1−a 1 ) *error change fuzzy value); and

if |error fuzzy value≧2, SNR threshold adjusting step fuzzy value=int(a 2 * error fuzzy value+(1−α 2 ) *error change fuzzy value),

wherein, int(x) denotes rounding, and both a 1 and a 2 are adjustable coefficients and meet the following requirement:

0≦a 1 ≦a 2 <1.

8. The method for controlling outer loop power as claimed in claim 5 , wherein a 1 is 0.5 and a 2 is 0.7.

9. The method for controlling outer loop power as claimed in claim 6 , wherein a 1 is 0.5 and a 2 is 0.7.

10. The method for controlling outer loop power as claimed in claim 7 , wherein a 1 is 0.5 and a 2 is 0.7.

11. The method for controlling outer loop power as claimed in claim 1 , wherein in step d), the actual SNR adjusting step value threshold is determined according to the fuzzy value of SNR threshold adjusting step value as shown in the following table:

fuzzy value of

−3

−2

−1

0

1

2

3

SNR threshold

adjusting step value

actual SNR threshold

−0.6

−0.3

−0.1

0

0.1

0.3

0.6

adjusting step value.

12. The method for controlling outer loop power as claimed in claim 5 , wherein in step d), the actual SNR adjusting step threshold is determined according to the fuzzy value of SNR threshold adjusting step value as shown in the following table:

fuzzy value of

−3

−2

−1

0

1

2

3

SNR threshold

adjusting step value

Actual SNR threshold

−0.6

−0.3

−0.1

0

0.1

0.3

0.6

adjusting step value.

13. The method for controlling outer loop power as claimed in claim 6 , wherein in step d), the actual SNR adjusting step value threshold is determined according to the fuzzy value of SNR threshold adjusting value step as shown in the following table:

fuzzy value of

−3

−2

−1

0

1

2

3

SNR threshold

adjusting step value

actual SNR threshold

−0.6

−0.3

−0.1

0

0.1

0.3

0.6

adjusting step value.

14. The method for controlling outer loop power as claimed in claim 7 , wherein in step d), the actual SNR adjusting step value threshold is determined according to the fuzzy value of SNR threshold adjusting step value as shown in the following table:

fuzzy value of

−3

−2

−1

0

1

2

3

SNR threshold

adjusting step value

actual SNR threshold

−0.6

−0.3

−0.1

0

0.1

0.3

0.6

adjusting step value.

15. The method for controlling outer loop power as claimed in claim 1 , wherein in step e), the SNR threshold is adjusted by the following steps of:

i) calculating a temporary SNR threshold in accordance with the following equation:

temporary SNR threshold=SNR threshold adjusting step value +previous SNR threshold; and

ii) determining a SNR threshold according to the temporary SNR threshold calculated in step i):

SNR threshold=predetermined upper limit when temporary SNR threshold>predetermined upper limit;

SNR threshold=predetermined lower limit when temporary SNR threshold<predetermined lower limit; and

else SNR threshold=temporary SNR threshold.

16. The method for controlling outer loop power as claimed in claim 11 , wherein in step e), the SNR threshold is adjusted by the following steps of:

i) calculating a temporary SNR threshold in accordance with the following equation:

temporary SNR threshold=SNR threshold adjusting step value+previous SNR threshold; and

ii) determining a SNR threshold according to the temporary SNR threshold calculated in step i):

SNR threshold predetermined upper limit when temporary SNR threshold>predetermined upper limit;

SNR threshold=predetermined lower limit when temporary SNR threshold<predetermined lower limit; and

else SNR threshold=temporary SNR threshold.

17. The method for controlling outer loop power as claimed in claim 12 , wherein in step e), the SNR threshold is adjusted by the following steps of:

i) calculating a temporary SNR threshold in accordance with the following equation:

temporary SNR threshold=SNR threshold adjusting step value+previous SNR threshold; and

ii) determining a SNR threshold according to the temporary SNR threshold calculated in step i):

SNR threshold=predetermined upper limit when temporary SNR threshold>predetermined upper limit;

SNR threshold=predetermined lower limit when temporary SNR threshold<predetermined lower limit; and

else SNR threshold=temporary SNR threshold.

18. The method for controlling outer loop power as claimed in claim 13 , wherein in step e), the SNR threshold is adjusted by the following steps of:

i) calculating a temporary SNR threshold in accordance with the following equation:

temporary SNR threshold=SNR threshold adjusting step value+previous SNR threshold; and

ii) determining a SNR threshold according to the temporary SNR threshold calculated in step i):

SNR threshold=predetermined upper limit when temporary SNR threshold>predetermined upper limit;

SNR threshold=predetermined lower limit when temporary SNR threshold<predetermined lower limit; and

else SNR threshold=temporary SNR threshold.

19. The method for controlling outer loop power as claimed in claim 14 , wherein in step e), the SNR threshold is adjusted by the following steps of:

i) calculating a temporary SNR threshold in accordance with the following equation:

temporary SNR threshold=SNR threshold adjusting step value+previous SNR threshold; and

ii) determining a SNR threshold according to the temporary SNR threshold calculated in step i):

SNR threshold=predetermined upper limit when temporary SNR threshold >predetermined upper limit;

SNR threshold=predetermined lower limit when temporary SNR threshold <predetermined lower limit; and

else SNR threshold=temporary SNR threshold.