Abstract
Path pruning, a new coding concept to achieve free distance enlargement for convolutional codes, is proposed in this paper. Through path pruning, every convolutional code can be used for unequal error protection (UEP), no matter whether it is originally a UEP Code. To avoid undesired path discontinuity and reduce possible path distance loss, a cascaded implementation together with a path-compatible criterion is proposed, under which path-compatible pruned convolutional (PCPC) codes are constructed. Necessary and sufficient conditions are also derived for a subclass of PCPC codes whose decoding can be dune by a single decoder for the parent code. Finally, some PCPC codes with good UEP capabilities found by computer search are given.