On unequal error protection for code symbols via active distances

This paper deals with unequal error protection for code symbols of convo-lutional codes. The unequal error protection can be achieved due to different distanceproperties of output sequences and is sometimes described in terms of the correspondingeffective free distances. However, in many situations the effective free distance does notprovide enough information on the error-correcting capability. We consider unequal errorprotection for code symbols via active distances, which gives us more detailed information.We also establish a connection to the effective free distances. Furthermore, we show thatwoven convolutional codes with inner warp are naturally suited for unequal error protectionof code symbols.