Efficient design to calculate extrinsic information for soft-in-soft-out (SISO) decoder

A soft-in soft-out functional block (SISO) that iteratively decodes a plurality of symbols, of a received data frame, that are encoded according to a rate control sequence, the SISO comprising:

• an extrinsic calculation functional block that calculates a plurality of min* extrinsic outputs for a plurality of input bits of a symbol within the plurality of symbols according to the rate control sequence;
• an extrinsic decoding functional block that employs the plurality of min* extrinsic outputs and the plurality of apps to generate a plurality of extrinsic values and a decoded plurality of input bits of the symbol within the plurality of symbols;
• and
• an uncoded bit selection determination functional block that generates an uncoded bit select value for use in selecting a best estimate of an uncoded bit from among a plurality of possible uncoded bit values when at least one symbol of the plurality of symbols of the received data frame comprises the uncoded bit.

An extrinsic calculation and decoding method that iteratively decodes a plurality of symbols, comprising:

• receiving a rate control sequence, a plurality of trellis metrics, a plurality of forward metric values (alphas) and a plurality of backward metric values (betas) corresponding to a trellis, and a plurality of ‘a priori’ probability values (apps);
• decoding the plurality of ‘a priori’ probability values (apps);
• selectively adding the decoded plurality of ‘a priori’ probability values (apps) to the plurality of trellis metrics thereby generating a plurality of ap_metrics according to the rate control sequence;
• performing min* processing on a plurality of combinations of input bits thereby generating a plurality of minimum extrinsic outputs and a plurality of log extrinsic outputs, the min* processing employs the plurality of forward metric values (alphas), the plurality of backward metric values (betas), and the plurality of ap_metrics;
• and
• decoding the input bits by selectively summing the plurality of minimum extrinsic outputs and the plurality of log extrinsic outputs thereby generating a plurality of extrinsic outputs.

An extrinsic calculation and decoding method that iteratively decodes a plurality of symbols, comprising:

• receiving a rate control sequence, a plurality of trellis metrics, a plurality of forward metric values (alphas) and a plurality of backward metric values (betas) corresponding to a trellis, and a plurality of ‘a priori’ probability values (apps);
• decoding the plurality of ‘a priori’ probability values (apps);
• selectively adding the decoded plurality of ‘a priori’ probability values (apps) to the plurality of trellis metrics thereby generating a plurality of ap_metrics according to the rate control sequence;
• performing min* processing on a plurality of combinations of input bits thereby generating a plurality of minimum extrinsic outputs and a plurality of log extrinsic outputs, the min* processing employs the plurality of forward metric values (alphas), the plurality of backward metric values (betas), and the plurality of ap_metrics;
• decoding the input bits by selectively summing the plurality of minimum extrinsic outputs and the plurality of log extrinsic outputs thereby generating a plurality of extrinsic outputs;
• calculating a first sum of values selected from the plurality of extrinsic outputs that is indicative of a possibility of one of the input bits comprising a value of 1;
• and.
• calculating a second sum of values selected from the plurality of extrinsic outputs that is indicative of a possibility of the one of the input bits comprising a value of 0;
• and
• assigning the value of the one of the inputs bits to the value 1 when a magnitude of the first sum is smaller than the second sum and alternatively assigning the value of the one of the inputs bits to the value 0 when a magnitude of the first sum is larger than the second sum;
• and
• selectively decoding an uncoded bit according to the rate control sequence by performing min* processing, employing one of the decoded input bits, the plurality of forward metric values (alphas), and the plurality of backward metric values (betas), to generate an uncoded bit select value for use in selecting a best estimate of an uncoded bit from among a plurality of possible uncoded bit values when at least one symbol of the plurality of symbols comprises the uncoded bit.