A comparison of different noise prediction schemes for high rate digital subscriber loop transmission

These schemes are the double side forward filter (DSFF) and the additional noise predictor (NP) schemes. Their optimal coefficient sets are derived under the minimum mean squared error criterion. Numerical examples show that both systems offer almost the same performance gain, over the system with only single side forward filter. In a system using a detector, however, the DSFF scheme needs only a few extra operations for computing the branch metric while the NP scheme requires a large number of extra operations. This is because the DSFF works outside the detector whereas the NP should be added to each survival path in the detector to avoid error propagation