Apparatus and method for decoding
View Patent ↗Coding section 205 recodes decoded data stored in decoded data storage section 204 , data conversion section 206 converts data “0” and “1” output from coding section 205 to “1” and “−1” respectively, sum-of-product calculation section 207 multiplies the data output from data conversion section 206 by the demodulated data (soft decision value) stored in demodulated data storage section 201 and then calculates the sum of the products for 1 TTI and stores the sum-of-product result for each data rate, data rate decision section 208 decides the data rate corresponding to a maximum value of the sum-of-product results as the data rate of the demodulated data. This makes it possible to improve the accuracy of data rate decision and reduce decoding errors of a received signal.
1. A decoding apparatus comprising:
a reference shift count calculation section that uses the number of shifts applied to each of a plurality of data strings, whose values are each represented by a power of 2, as an index involved in normalization, averages the number of shifts applied to the plurality of data strings, and calculates a reference shift count based on the average number of shifts;
a normalization section that performs the normalization by shifting each of the data strings based on the reference shift count so as to provide each of the data strings with a presumptively common exponent; and
an error correcting decoding section that carries out error correcting decoding processing on the normalized data strings.
2. The decoding apparatus according to claim 1 , wherein the normalization section performs the normalization on each data string by carrying out a right shift of the data string by a value obtained by subtracting the reference shift count from the shift count corresponding to the data string.
3. The decoding apparatus according to claim 1 , wherein the normalization section performs the normalization for each data string by carrying out a right shift of the data string by a second value obtained by dividing by 2 a first value obtained by subtracting the reference shift count from the shift count corresponding to the data string.
4. The decoding apparatus according to claim 1 , wherein the normalization section performs the normalization for each data string by carrying out a right shift of the data string by a second value obtained by dividing by 2 a first value obtained by subtracting the reference shift count from the shift count corresponding to the data string when the first value is 0 or greater and performs the normalization by carrying out a right shift by the first value when the first value is smaller than 0.
5. The decoding apparatus according to claim 1 , wherein the normalization section performs the normalization for each data string without shifting the data string when a first value obtained by subtracting the reference shift count from the shift count corresponding to the data string is 0 or greater and performs the normalization by carrying out a right shift of the data string by a second value obtained by dividing by 2 the first value when the first value is smaller than 0.
6. The decoding apparatus according to claim 1 , wherein the normalization section performs the normalization for each data string by carrying out a right shift of the data string by a second value obtained by dividing by 2 a first value obtained by subtracting the reference shift count from the shift count corresponding to the data string when the first value is equal to or greater than ½ of a limited bit width and performs the normalization by carrying out a right shift of the data string by the first value when the first value is smaller than ½ of the limited bit width.
7. The decoding apparatus according to claim 1 , wherein the normalization section performs the normalization for each data string without shifting the data string when a first value obtained by subtracting the reference shift count from the shift count corresponding to the data string is equal to or greater than ½ of a limited bit width and performs the normalization by carrying out a right shift of the data string by a second value obtained by dividing by 2 the first value when the first value is smaller than ½ of the limited bit width.
8. A decoding apparatus comprising:
a first reference shift count calculation section that: (1) uses the number of shifts applied to each of a plurality of data strings, whose values are each represented by a power of 2, as an index involved in normalization, (2) averages the number of shifts, in slot units after RAKE combining, applied to the plurality of data strings, and (3) calculates a first reference shift count based on the average number of slot unit shifts;
a first normalization section that performs first normalization by shifting each of the data strings in slot units based on the first reference shift count so as to provide each of the first normalized data strings with a presumptively common exponent;
a second reference shift count calculation section that averages the number of shifts, in frame units, applied to the first normalized data strings and calculates a second reference shift count based on the average number of frame unit shifts;
a second normalization section that performs second normalization by shifting the first normalized data strings in frame units based on the second reference shift count so as to provide each of the second normalized data strings with a presumptively common exponent; and
an error correcting decoding section that carries out error correcting decoding processing on the second normalized data strings.
9. The decoding apparatus according to claim 8 , wherein the first normalization section performs the first normalization by carrying out a right shift of each of the data strings by a value obtained by subtracting the first reference shift count from the corresponding shift count of the data string in slot units.
10. The decoding apparatus according to claim 8 , wherein the second normalization section performs the second normalization by carrying out a right shift of each of the first normalized data strings by a value obtained by subtracting the second reference shift count from the shift count of the corresponding first normalized data string in frame units.
11. A program that implements:
a reference shift count calculation function that uses the number of shifts applied to each of a plurality of data strings, whose values are each represented by a power of 2, as an index involved in normalization, averages the number of shifts applied to the plurality of data strings, and calculates a reference shift count based on the average number of shifts;
a normalization function that performs the normalization by shifting each of the data strings based on the reference shift count so as to provide each of the data strings with a presumptively common shift count; and
an error correcting decoding function that carries out error correcting decoding processing on the normalized data strings.
12. A program that implements:
a first reference shift count calculation function that: (1) uses the number of shifts applied to each of a plurality of data strings, whose values are each represented by a power of 2, as an index involved in normalization, (2) averages the number of shifts, in slot units after RAKE combining, applied to the plurality of data strings, and (3) calculates a first reference shift count based on the average number of slot unit shifts;
a first normalization function that performs first normalization by shifting each of the data strings in slot units based on the first reference shift count so as to provide each of the first normalized data strings with a presumptively common shift count;
a second reference shift count calculation function that averages the number of shifts, in frame units, applied to the first normalized data strings and calculates a second reference shift count based on the average number of frame unit shifts;
a second normalization function that performs second normalization by shifting the first normalized data strings in frame units based on the second reference shift count so as to provide each of the second normalized data strings with a presumptively common exponent; and
an error correcting decoding function that carries out error correcting decoding processing on the second normalized data strings over a plurality of normalized frames.
13. A decoding method comprising:
using the number of shifts applied to each of a plurality of data strings, whose values are each represented by a power of 2, as an index involved in normalization;
averaging the number of shifts applied to the plurality of data strings;
calculating a reference shift count based on the average number of shifts;
performing the normalization by shifting each of the data strings based on the reference shift count so as to provide each of the data strings with a presumptively common exponent; and
carrying out error correcting decoding processing on the normalized data strings.
14. A decoding method comprising:
using the number of shifts applied to each of a plurality of data strings, whose values are each represented by a power of 2, as an index involved in normalization;
averaging the number of shifts, in slot units after RAKE combining, applied to the plurality of data strings;
calculating a first reference shift count based on the average number of slot unit shifts;
performing first normalization by shifting each of the data strings in slot units based on the first reference shift count so as to provide each of the first normalized data strings with a presumptively common shift count;
averaging the number of shifts, in frame units, applied to the first normalized data strings;
calculating a second reference shift count based on the average number of frame unit shifts;
performing second normalization by shifting the first normalized data strings in frame units based on the second reference shift count so as to provide each of the second normalized data strings with a presumptively common exponent; and
carrying out error correcting decoding processing on the second normalized data strings over a plurality of normalized frames.