In this work, the performance of a class of asymmetric turbo codes, which are
composed of mixed types of non-identical, recursive systematic convolutional codes
has been investigated.
Internal pilot insertion technique is utilized to further improve the BER performance of
turbo code especially at high SNR. The minimum distance of turbo codes and the
multiplicity of low weight codewords can be improved by inserting pilot bits within the
sequence of information bits entering the turbo encoder. This technique was shown to
be useful on the symmetric and asymmetric turbo coded signals.