Abstract: A method for performing a table look-up operation on a first table having N entries includes generating a second table having kN entries based on the first table. The method includes generating a first data field for the second table including table index values having a second interval derived from a first interval of the table index values of the first table and represented by an n-bit binary number; and generating a second data field including computed table values derived from the computed table values of the first table or computed based on the function defining the second data field. The method further includes computing an index value z, extracting address bits from the index value z, where the address bits are data bits more significant than the (n-1)th bit of the index value z, and addressing the second table using the address bits.

Abstract: An index value generation circuit for use in a turbo decoder for computing the index value z=|x1−x2| for addressing a table used for computing the function log(ex1+ex2) or 1n(ex1+ex2) is described. Parameters x1 and x2 are first and second argument values derived from the input data. The index value generation circuit computes the difference of the first argument x1 and the second argument value x2 by taking the 2's compliment of the second argument value and adding the first argument value to the negative value of the second argument value x2. If the difference is a negative number, the index value generation circuit computes the absolute value of the difference by taking the 1's compliment of the difference x1-x2. In this manner, the index value z used to address the table for computing the function log(ex1+ex2) or 1n(ex1+ex2) in the decoding operation can be generated quickly.

Abstract: A method for performing a table look-up operation on a first table having N entries includes generating a second table having kN entries based on the first table. The method includes generating a first data field for the second table including table index values having a second interval derived from a first interval of the table index values of the first table and represented by an n-bit binary number; and generating a second data field including computed table values derived from the computed table values of the first table or computed based on the function defining the second data field. The method further includes computing an index value z, extracting address bits from the index value z, where the address bits are data bits more significant than the (n−1)th bit of the index value z, and addressing the second table using the address bits.

Abstract: A stop iteration criterion in a turbo decoder is provided where the turbo decoder monitors the bit decisions from each constituent decoder for each data bit at each iteration and ceases further iterations when the bit decisions converge. In a turbo decoder having N-number of constituent decoders, the bit decisions from each of the N constituent decoders are compared in each iteration. When the bit decisions of the N constituent decoders differ, the turbo decoder proceeds to the next decoding iteration. When the bit decisions of the N constituent decoders converge, the decoding iteration is stopped and the bit decisions are provided as the final decoding result.