Patent ID: 6452984
Filing Date: 2002-09-17
Classification: H03M

Abstract:
A method for decoding received data that has been generated by encoding a sequence of precoding bits with a convolutional encoder that generates convolutional codes based on an input sequence of precoding bits, the encoder characterized by a constraint length K and a rate k/n, the method comprising the steps of:generating an a priori probability that a first sequence of preceding bits has a particular value, the first sequence of preceding bits corresponding to an encoder state at a particular time; applying a metric function to a test sequence that corresponds to an encoded version of a preceding sequence that includes the first sequence, wherein the metric function is a function of the a priori probability, wherein the function of the a priori probability is a function of the logarithm of the a priori probability; and employing the metric to decode the received data with a maximum likelihood sequence estimator, wherein the function of the logarithm of the a priori probability is equal to (&sgr;2/&agr;2) multiplied by the natural logarithm of the a priori probability; wherein &sgr;2 is an estimate of the variance of noise added by a channel through which the received data propagated and &agr;2 is the average energy per symbol comprising part of the received data.