An iterative algebraic method called state reduction algorithm has been proposed to compute the distance spectrum of time-invariant convolutional codes. This method is based on an iterative manipulation of the symbolic adjacency matrix of the state diagram. This work defines new adjacency matrices for time-varying convolutional codes to allow the application of this algorithm for this class of codes.
['Cecilio Pimentel']
On the Weight Enumerator of Periodically Time-Varying Convolutional Codes