Patent ID: 6163581
Filing Date: 2000-12-19
Classification: H03M,H04B,H04L

Abstract:
A method of computing a decision bit for an output node associated with an output state in a trellis butterfly, comprising the steps of:computing a first branch metric between a first input node and the output node, the first input node associated with a first input path metric, wherein the first branch metric defines a difference between an error free first state of a convolutionally coded sequence and a measured first state of the convolutionally coded sequence;adding the first input path metric to the first branch metric to produce a first candidate output path metric;computing a second branch metric between a second input node and the output node, the second input node associated with a second input path metric wherein the second branch metric defines a difference between an error free second state of the convolutionally coded sequence and a measured second state of the convolutionally coded sequence;adding the second input path metric to the second branch metric to produce a second candidate output path metric; andconfiguring the decision bit designating a path to the output node as a minimum error path based upon a parity of the output node state and upon whether the first candidate output path metric is greater than the second candidate output path metric.