Refinement of the DS2 Bound and its Extensions for Discrete Memoryless Symmetric Channels

Strengthened versions of the DS2 bound and its extensions for the transmission of linear codes over discrete memoryless output symmetric channels are presented. Probability likelihood ratios under the list decoding rule are approximated by sigmoid functions. The effect of the erroneous decoding region in the calculation of list error decoding probability is considerably reduced. Numerical results illustrate the new bounds.