Unequal error protection explained by state-transition graphs

In this paper unequal error-correcting capabilities of convolutional codes are studied. State-transition graphs are used for investigating the error-correcting capabilities for specific inputs or outputs of given convolutional encoding matrices. Active burst input- and output-distances are defined and shown to be generalizations of the active burst distance. These new distances provide better estimates of the error-correction capability, especially when we communicate close to or above the channel capacity and they are connected to the corresponding free input- and output-distances via lower bounds