Decoding device and decoding method

1. A decoding device for decoding an LDPC (Low Density Parity Check) code, said decoding device comprising:

a first operation unit for performing a check node operation for decoding said LDPC code, said operation including an operation of a nonlinear function and an operation of an inverse function of said nonlinear function; and

a second operation unit for performing a variable node operation for decoding said LDPC code;

wherein said first operation unit includes

a first converting unit for converting a first quantization value assigned to a numerical value into a second quantization value representing a numerical value with a higher precision than said first quantization value, and

a second converting unit for converting said second quantization value into said first quantization value, and

in processing performed as said check node operation and said variable node operation, said first operation unit and said second operation unit use said second quantization value in processing from after the operation of said nonlinear function to before the operation of said inverse function, and use said first quantization value in the other processing.

2. The decoding device as claimed in claim 1 ,

wherein said first operation unit performs said check node operation and a part of said variable node operation; and

said second operation unit performs another part of said variable node operation.

3. The decoding device as claimed in claim 1 ,

wherein said second quantization value represents a numerical value in a dynamic range narrower than a dynamic range of a numerical value represented by said first numerical value.

4. The decoding device as claimed in claim 1 ,

wherein said second quantization value has a smaller quantization width than said first numerical value.

5. The decoding device as claimed in claim 1 ,

wherein said second quantization value has a larger number of bits than said first numerical value.

6. The decoding device as claimed in claim 1 ,

wherein said first converting unit is a LUT (Look Up Table) that receives said first numerical value as an input and outputs a result of calculating said nonlinear function by said second quantization value; and

said second converting unit is a LUT that receives said second numerical value as an input and outputs a result of calculating said inverse function by said first quantization value.

7. A decoding method of a decoding device for decoding an LDPC (Low Density Parity Check) code, said decoding device including

a first operation unit for performing a check node operation at a check node for decoding said LDPC code, said check node operation including an operation of a nonlinear function and an operation of an inverse function of said nonlinear function, and

a second operation unit for performing a variable node operation at a variable node for decoding said LDPC code, said decoding method comprising:

a first converting step for converting a first quantization value assigned to a numerical value into a second quantization value representing a numerical value with a higher precision than said first quantization value; and

a second converting step for converting said second quantization value into said first quantization value;

wherein in processing performed as said check node operation and said variable node operation, said first operation unit and said second operation unit use said second quantization value in processing from after the operation of said nonlinear function to the operation of said inverse function, and use said first quantization value in the other processing.