ON LOCALLY INVERTIBLE RATE-1 N CONVOLUTIONAL ENCODERS/

A locally invertible convolutional encoder has a local inverse defined as a full rank w x w matrix that specifies a one-to-one mapping betwe en equal-length blocks of information and encoded bits. In this corres pondence, it is shown that a rate-1/n convolutional encoder is nondege nerate and noncatastrophic if and only if it is locally invertible. Lo cal invertibility is used to obtain upper and lower bounds on the numb er of consecutive zero-weight branches in a convolutional codeword. Fu rther, existence of a local inverse can be used as an alternate test f or noncatastrophicity instead of the usual approach involving computat ion of the greatest common divisor of n polynomials.