US 7,032,156 B2 · Apparatus and method for reducing Bit Error Rates (BER) and Frame Error Rates (FER) using turbo decoding in a digital communication system

Abstract

An Forward Error Correction (FEC) apparatus and method for reducing Bit error rates (BER) and Frame Error Rates (FER) using turbo decoding in a digital communication system. In a constituent decoder for decoding a turbo code, a first adder calculates the LLR of a received code symbol by calculating the difference between the probability of the code symbol being 1 and that of the code symbol being 0 at an arbitrary state of a turbo decoding trellis. A second adder adds the transmission information and a priori information of the code symbol. A third adder calculates the difference between the outputs of the first and second adders as extrinsic information. A first multiplier multiplies the output of the third adder by a predetermined weighting factor as a feedback gain. A correction value calculator calculates a correction value using the difference between the best metric and the second best metric of the code symbol. A fourth adder adds the correction value to the output of the first multiplier.

Claims9

Dependent claims

A constituent decoding method for decoding a turbo code, comprising the steps of:

(1) calculating the best and second best metrics of metrics being the sums of state metrics and a branch metric for a received information symbol in a turbo decoding trellis at an arbitrary time point during turbo decoding of the information symbol;
(2) calculating the difference between the best metric for the information symbol being 0 and the best metric for the information symbol being 1;
(3) calculating the difference between the second best metric for the information symbol being 0 and the second best metric for the information symbol being 1;
(4) calculating the difference between the best metric difference and the second best metric difference and multiplying the calculated difference by a weighting factor, so that the metrics being the sums of the state metrics and the branch metric are linear;
and
(5) updating the log likelihood ratio (LLR) of the information symbol using the best metric difference obtained in the step of (2) and the product obtained in the step of (4) and deciding the value of the information symbol according to the updated LLR.

3 more elements

A constituent decoder for decoding a turbo code, comprising:

a first adder for calculating the difference between the best metric for a received information symbol being 1 and the best metric for the information symbol being 0 in a turbo decoding trellis at an arbitrary time point during turbo decoding the information symbol;
a second adder for adding the transmission information and a priori information of the information symbol;
a third adder for calculating the difference between the outputs of the first and second adders and outputting the difference as extrinsic information;
a first multiplier for multiplying the output of the third adder by a predetermined weighting factor as a feedback gain;
a correction value calculator for calculating a correction value using the difference between the best metric and second best metric of the received information symbol;
and
a fourth adder for adding the correction value to the output of the first multiplier.

4 more elements

Dependencies are inferred from the claim text.

Apparatus and method for reducing Bit Error Rates (BER) and Frame Error Rates (FER) using turbo decoding in a digital communication system

Life of this patent

Apparatus and method for reducing Bit Error Rates (BER) and Frame Error Rates (FER) using turbo decoding in a digital communication system

Life of this patent

Abstract

Claims9