A CASCADABLE PRAGMATIC BLOCK DECODING ALGORITHM EXPLOITING CHANNEL MEASUREMENT INFORMATION

The complexity of algorithms to perform soft decision decoding on bloc k codes has impeded their inclusion in practical systems. A well-known class of algorithms for decoding block codes utilizing channel measur ement information along with the algebraic properties of the code are the Chase algorithms.' In this paper a decoding method similar to Chas e's third algorithm is presented. However, in this method, a single te st pattern or alternate codeword makes up one stage of the decoder. Th e method uses information from the previous decoding(s) to assist in g enerating a test pattern. This single stage 'Second Chance Algorithm' can then be extended to a 'Third Chance Algorithm' (and beyond) to enh ance performance. The method does not invoke the hard decision decoder as often as the Chase algorithms.